STR 2012 2 e Complete
Transcript of STR 2012 2 e Complete
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2/2012
PolymersPolymer production technology Customized foam manufacturing
New polymer pilot plant Flexible pumps for polymers
Solutions for the plastics industry Efficiency through coated tools Successful polymer analysis
Panorama World-famous in motor sports Insightful hot spots
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New benchmarks for polymer technology
Dear Technology Professionals, Customers, and Partners,
Polymers are considered the material of choice for the cost-effective production of
mass products. However, the need for technically demanding solutions continues
to grow, so that many factors other than the material and manufacturing costs have
become decisive for success in the plastics market.
Plastics manufacturers are looking for flexible manufacturing processes in
order to be able to offer tailor-made products to their customers. The right mix
of raw materials and additives is just as decisive as the scalability, efficiency,
and controllability of the processes. Ecological aspects, such as energy con-
sumption, alternative raw materials, and degradability, play an increasingly
important role.
In this edition of the Sulzer Technical Review, you can find out how Sulzer is
setting new sustainable benchmarks for technological development in the polymer
industry.
Thanks to a significant investment, new polymer pilot installations and an expanded
test center are available to our clients in the process technology business. A number
of articles in this issue provide insight into our latest mixing and reaction technology
for polymers.
Because of the wide range of fluid properties needing to be processed, polymer
processes are a great challenge for pump technology. We will show you how our
pumps master these challenges with the greatest flexibility.Tools for the manufacture of plastic products require special surfaces. Our surface
technology division offers coating solutions and surface treatments for a multitude
of requirements.
Metrological analyses are essential in order to guarantee optimal plastic properties.
In this edition, you can read how we support our clients in polymer analysis and
solve even the most difficult cases with a detective-like flair.
I hope you enjoy reading these articles.
Klaus Stahlmann
CEO Sulzer
EDITORIAL
| Sulzer Technical Review2 2/2012
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O5 ; +6=9:A scanning electron micrograph of polystyrene foam shows theair-filled hollow cells that make the material an excellent insulator.
Keystone / Science Photo Library / Eye of Science
CONTENT
Sulzer Technical Review |2/2012 3
Polymers
4 Flexible foam productionCustomized manufacturing of expandable polystyrene
8 Sustainable pumping solutions for polymer manufacturingFlexible and durable high-efficiency pumps for the chemical process industry
12 New bioplastics pilot plantInterview with Lorenzo Ghelfi, Sulzer Chemtech
14 More effective manufacturing through coated toolsEfficient processing of plastics
19 Spider silk as a superpolymerSulzer analogy
20 Following the trail of polymeric evidencePolymer analysisbetween measurement and interpretation
Panorama
25 Welcome to Sulzer Metco in LimogesSulzer world
26 Insightful hot spotsThermographic inspection of industrial gas turbine components
30 Events & News
31 Imprint
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The industrial polymerization of
styrene to polystyrene (PS) started
in the early 20th century and was
followed by the development of expan-
dable PS beads around 60 years ago. EPS
is a particle foam made by expanding
PS beads that contain a blowing agent
usually pentane. Steam heating causes
the beads to expand, and the final shape
is achieved by molding the pre-expanded
beads with steam and pressure. There
are numerous applications for EPS on
the market, and block and shape molding
are the most important conversion pro-
cesses currently employed to fabricate
foam products from EPS. In particular,
by using shape molding, various products
can be obtainedfor example, packaging
solutions, plaster, or sports equipment
many of which profit from customized
EPS formulations that add color or
mechanical properties.
Melt impregnation allows customized
production
In the common process chain, EPS resin
suppliers produce impregnated poly-
styrene resin granulates with the blowing
agent in large-scale industrial facilities.
The EPS is then sold to EPS molders.
They manufacture end productssuch
as packaging, construction material, or
drinking cupsaccording to customer
specifications.
Flexible foam productionThe properties of expandable polystyrene (EPS), one of the most important
foamed plastics in the world, can be significantly influenced by additives. Such
additives can repel insects, make the material flame resistant, or improve thermal
insulation. Sulzer Chemtech has developed a flexible process particularly suited
for the economical production of customized, special-grade EPS.
Sulzers EPS pilot plant allows process optimization, sample production, and feasibility testing for customers.
Customized manufacturing of expandable polystyrene
| Sulzer Technical Review4 2/2012
POLYMERS
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Sulzer Chemtech offers a continuous
process for producing EPS granulates
from PS on an industrial scale of up to
100 000t per year (see STR 1/2009, p.6).
In this process, the melt is directly
impregnated with the blowing agent and
the required additives, and it is then sent
to an underwater pelletization process.
The melt impregnation has several
advantages over the conventional sus-
pension process. The product quality is
consistent and can be easily controlled,
as the additives and the blowing agent
are directly injected into the melt.
Environmental benefits and energy
savings
The environmental benefits include:
Lower water consumption
Straightforward recycling of excess
material
On an industrial scale, the hardware for
this process includes Sulzer Chemtech
static mixers and heat exchangers. In
particular, when connecting the Sulzer
EPS process directly to a polystyrene
melt plant, the static mixing approach
results in significant energy savings, as
the resin does not
need to be melted
again. This offers the
possibility of operat-
ing competitive styrene-to-EPS plants for
global-scale production of EPS commodi-
ties, for example, for innovative insulation
solutions. In fact, with the introduction
of a melt-based EPS process in the late
1990s by Sulzer, the technological basis
for the production of pigmented, flame-
resistant EPS for housing insulation was
established, and this gave rise to the
development of a number of innovative
materials using different additives.
Improving thermal insulation with
pigments
Several parameters, such as foam density,
choice of blowing agent, and cell size
distribution, can influence the thermal-
insulation properties of EPS foam. The
genuine advantage of EPS foam as insu-
lation material over competing insulation
solutions like polyurethane, mineral
wool, or extruded polystyrene foam
(XPS) is its low density and, hence, its
relatively low price. However, the insu-
lative properties significantly deteriorate
with decreasing density. Three mecha-
nisms contribute to the thermal conduc-
tivity of EPS (see info box):
Conduction
Convection
Radiation (mainly infrared).
With decreasing EPS density, the share
of infrared radiation strongly increases.
This effect can be avoided through pig-
mentation. Pigments, e.g., graphite, car-
bon, or aluminum particles, added to
Sulzer Technical Review |2/2012 5
POLYMERS
Low-lambda development
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the EPS can absorb and/or reflectinfrared radiation and thus improve ther-
mal insulation1. This way, the insulative
property of low-density EPS can reach
the same level as EPS with a density two
to three times higher. Using optimized
mixing technology as well as the right
combination of additives in the process
leads to an improved dispersion of the
pigments in the final product and helps
to lower the additive consumption in
the Sulzer process compared to other
processes.
Meeting environmental require-
ments: alternative flame retardants
A disadvantage of using plastics in con-
struction is their flammability. Polystyrene,
in particular, burns readily and EPS foam,
unless equipped with flame retardants,
does not fulfill common building codes
relating to flame spread and smoke devel-
opment. Therefore, the material has to
be either used in combination with an
additional flame barrier on the side of
the construction method or impregnated
with suitable flame retardants. The most
widely used additive for this application
is hexabromocyclododecane (HBCD), a
highly brominated flame retardant with
more than 70wt% bromine per molecule.
HBCD has been the flame retardant
of choice in EPS for
several decades
now, because it is
very efficient: Typi-
cally, HBCD levels between 0.7 % and
3 % depending on the type of synergist
and process usedare required for
building insulation to reach the desired
flame retardancy. In particular, the use
of synergists imposes very efficient
temperature and shear control on the
production process. With decomposition
temperatures as low as 150C, as is the
case for commonly used peroxide
synergists, it becomes a prerequisite inmelt impregnation to cool and maintain
a low temperature and shear profile.
This factor has to be taken into account
for the design of mixers, extruders, and
pelletizers.
Flexible process allows the use of
HBCD substitutes
Recently, the toxicity and the environ-
mental impact of HBCD have become
matters of concern. Measurements have
shown that the material bioaccumulates
and biomagnifies so that several
environmental protection agencies
have put the chemical on their lists
of concerns. This development has
prompted the EPS industry to start the
search for a substitute for HBCD. Due
to its ingenious design and efficient
temperature control, the Sulzer EPS
process is much more flexible than classic
suspension technology as it allows
the use of new flame retardants currently
in development.
Defined distribution of particle sizes
The EPS quality is not only influenced
by the composition of the material but
also by the geometry of the molded beads.
An even, spherical shape of the beads
ensures the best particle fusion. The diam-
eter required for the EPS particles
depends on the intended use of the final
product. Different size classes are
typically defined for insulation, packag-
ing, food containers, or cups. And an
optimal mold fill is supported by a
narrow, uniform bead size distribution.
Together with Automatik Pelletizing
Systems, part of the MAAG group which
was recently acquired by Dover Corpo-ration, Sulzer Chemtech has further de-
veloped the existing underwater pelleti-
zation technology for stable production
of uniform EPS, in particular, EPS con-
taining pigments and flame retardants.
Due to its outstanding sphericity and pre-
cise pellet size distribution2, the product
can be processed like suspension product
without prior screening or sieving. Due
to a unique die plate design and efficient
heating, die freezing can be minimized
even for small bead sizes below 1mm.
| Sulzer Technical Review6 2/2012
POLYMERS
2 Prefoamed EPS beads from Sulzers EPS process show excellentsphericity and cell size distribution.
100m
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Premature foaming of the beads is
avoided thanks to pressure and temper-
ature control in the closed pelletization
water circuit.
Small-scale, economical production
The melt impregnation technology
represents a tremendous potential for
product innovation in the PS foam busi-
ness, not only on a large production scale
but also on a scale suitable for specialized
products. EPS converters, who are very
closely connected to end customers, typ-
ically have vast knowledge of the product
requirements and limitations of existing
EPS products for the applications they
serve. Unlike the big resin producers
with their commodity-grade EPS, con-
verters increasingly feel the need to differ
from their competition and to develop
niche products with special properties.
Because annual consumption can easily
reach 10000 t per year, the production
of their own EPS resin with a melt impreg-
nation plant suddenly becomes attractive,
in particular with PS resin widely
available at relatively low prices.
Simplified extruder process
Applying the in-depth process expertise
from a decade of EPS process develop-
ment, Sulzer Chemtech has developed
a second-generationEPS process suited,
in particular, to small-
scale production 3.
Using a combination of a twin-screw
extruder in which PS or EPS, blowing
agent, and all required additives are com-
poundedand Sulzers proprietary melt
coolers, the engineers have designed a
simplified manufacturing unit that is
attractive for smaller capacities of about
500 3000kg per hour. This extruder
process, the result of a joint cooperation
with the renowned German extruder
manufacturer Coperion, allows for the
economic production of EPS specialties
even on scales adapted to the requirements
of larger converters.
Sulzer supports EPS converters who
want to develop their own foam formu-
lations. They can produce and test cus-
tomized EPS grades with various addi-
tives in Sulzers pilot test facilities. The
clients benefit from the broad experience
that Sulzer Chemtech and its partners
have gathered with melt impregnation
technology.
Process innovation for the
environment
From the very beginning, Sulzer has
focused its process development on envi-
ronmentally friendly solutions for EPS
production. This designation encompass-
es two major areas: recycling capabilities
and the use of alternative blowing agents.
Because EPS is a lightweight, single-use
product with a decomposition time of
several thousand years in nature, the
end-of-life debate has always had a neg-
ative imprint on the product image. At
the same time, the commonly used blow-
ing agent pentane for foaming EPS has
a critical global warming potential and
falls under strict regulations in many
countries and legislations. While suspen-
sion polymerization is rather inflexible
in view of addressing these aspects, melt
impregnation offers a lot of room for
process innovation. Sulzer Chemtech
develops and offers technology for the
recycling of both unfoamed, impregnated
EPS from production (e.g., off-spec mate-
rial, unsold material from stock, etc.) and
compressed foam from consumer recy-
cling or production internal sources (cut-
off, blocks, etc.). Those materials can be
used as feed stream and be 100 % reuti-
lized for production of virgin EPS resin.
By using alternative blowing agents,
which do not fall under the regulations
of volatile organic compounds (VOC) yet
have similar properties to those ofpentane, converters can save significant
money on pentane abatement systems
and VOC taxes that may apply in some
countries. Development of these process
innovations is currently ongoing within
Sulzer Chemtech.
Sulzer Technical Review |2/2012 7
POLYMERS
3 Sulzers EPS process is suited for small-scale EPS production (5003000 kg/h).
P N5Sulzer Chemtech LtdSulzer-Allee 488404 WinterthurSwitzerlandPhone +41 52 262 50 22
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/!c$*++#4 "+ /$! !c4c*# +" EPS.
Blowing agent
Polymer feed(PS, EPS,recyclate)
Additives(FR, pigments)
Gravimetric dosing systems
Twin-screw extruder (ZSK MEGA compounder) SMR melt cooler Gear pump
EPS micropellets
Underwater pelletizer
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The wide range of processes in the
polymer-manufacturing industries
leads to an extensive scope of pump-
ing necessities. It is essential to the oper-
ation of polymer plants that the process
pumps fulfill a variety of requirements.
In most polymer plants, pumps generate
the majority of energy cost. Therefore,
efficiencyof both hydraulics and elec-
trical drive is important. Another, even
more crucial, criterion is the reliability
of the pumps, because unplanned inter-
ruptions of the often-complex chemical
processes can cause significant cost
increases and environmental impact.
Pumping various fluids
With many installed units operating
globally, Sulzer s AHLSTAR series is the
worlds largest process pump series for
demanding industrial processes including
polymer processes. The capability to
work with all types of liquids makes
this pump range particularly suitable for
the challenging pumping operations
required in chemical processes. Whereas
the basics of pumping are the same in
all applicationsmoving a liquid and
increasing its pressurethe specific
parameters of the liquids to be processed
can differ dramatically. The fluids can
vary in viscosity or they can contain
fibers or solids.
Sustainable pumping solutionsfor polymer manufacturingIn the polymer-manufacturing industry, raw materials undergo chemical conversion during
their processing into finished products. These conversion processes very often require
conveying fluids with a wide range of characteristics. The liquids can be very hot or cold,
they may be chemically aggressive, or they can contain solids or fibers. With the AHLSTAR
process pump series, Sulzer meets the requirements of chemical process industries.
AHLSTAR pumps are designed for safe operation and easy maintenance and service.
Flexible and durable high-efficiency pumps for the chemical process industry
| Sulzer Technical Review8 2/2012
POLYMERS
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Sulzer engineers had to consider all
those and more boundary conditions
when they designed the over ten different
impellers that make the AHLSTAR range
suited for almost every hydraulic require-
ment. Whether closed or open, dedicated
for low discharge, or wear-resistant,
impellers make it possible for the
AHLSTAR pumps to work with slurries,
clear, or contaminated liquids or fluids
containing solids of various sizes. These
process pumps can work at temperatures
of up to 260 C and pressures of up to
2.5 MPa, which is roughly equivalent to
the pressure 250 m
below water. With
the right choice
of materials, these
pumps operate corrosion free even
when handling liquids with extreme
pH values from 0 up to 14.
Exceeding international standardsInternational standards define sets of
minimum criteria that clients can expect
to be fulfilled by standard pumps.
Depending on the specification, the
following standards are applied to
centrifugal pumps:
API 610 (ISO 13709) standard for
demanding processes in the oil and
gas and hydrocarbon industries
ISO 5199 and ISO2858 (as well as
American standards ASME73.1) for
industrial processes
European standard EN 733 for light
industrial processes
The metric standard ISO 5199, for
example, covers the requirements for
pumps of back pullout construction as
used primarily in the chemical and petro-
chemical industries. It includes design
features relating to installation, mainte-
nance, and safety. Other codes define
main dimensions and operating ranges
of the pumps.
The pumps of the AHLSTAR series
fulfill ISO5199 and ISO 2858 interna-
tional standards relating, e.g., to dimen-
sions of flanges and base plates and,
therefore, do not require special effort
to install or maintain within existing
pipework. When it comes to performance
and quality, the pumps of the AHLSTARrange have extra features exceeding
the basic requirements and even sur-
pass the international standards
governing technical performance and
quality 1.
Solutions for liquids with high gas load
Conventional centrifugal pumps can han-
dle liquids with gas content below 4%,
but gas bubbles collected in the impeller
eye do impair pumping and will reduce
capacity and head. At a gas content of
Sulzer Technical Review |2/2012 9
POLYMERS
Non-Newtonian fluid behavior.
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Typical fluid properties in
polymer manufacturing
Viscosity is an important fluid property
that is relevant for pumping technology.
The viscosity describes a fluids resist-
ance to shear stress. Fluids like water
have constant viscosities and are
called Newtonian fluids.
Molten polymers and salt solutions
show non-Newtonian fluid behavior.
Their viscosity depends on the rate
of shear and can even be time
dependent.
1 The performance of theAHLSTAR pumps exceedsstandard requirements.
over 93%
efficiency
The shear-thinning behavior of poly-
mers (also known as pseudoplastic
behavior) means that the viscosity
becomes smaller if the rate of shearing
increases. Such changing viscositycoefficients have to be considered in
the pump design for polymer manu-
facturing.
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Shear thinning(pseudoplastic) fluids
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above 4 %, pumping is very unstable,
and, without special measures, it requires
excessive overdimensioning of the pump.
Sulzer has found a solution to this cus-
tomer requirement by offering degassing
and self-priming units in the AHLSTAR
series, which will stabilize centrifugal-
pump operation with liquids containing
up to 40 % weakly bonded gases or up
to 70 % strongly bonded gases. The
AHLSTAR pumps can be fitted with self-
priming or degassing units to start the
pump with the inlet pipe empty or
to help the pump operate with liquid
containing high gas content, where
conventional centrifugal pumps would
lose suction compatibility.
High efficiency, low energy cost
Energy costs make up about 80 % of the
life cycle cost of a process pump. Sulzer's
engineers have considered this fact when
designing the AHLSTAR pump series.
Traditionally, pumps are operated with
a constant-speed drive motor and a flow
control valve to
adjust the discharge.
This operating mode
can be compared to
always driving a car at full throttle engine
speed and only using the brakes tocontrol the velocity. If the pump motor
is operated using an electronic frequency
converter, it is possible to vary the
rotating speed of the impeller and, thus,
to run the pump at high efficiency in a
broad operating range, making energy
savings of up to 60 % possible. Further-
more, when operated with variable
speed, the pump runs smoothly without
recirculation and with lower vibration
and noise due to the low internal
hydraulic loads. With this smoother oper-
ation, customers benefit from longer
pump life, fewer unexpected shutdowns,
and lower maintenance costs.
Superior reliability
Centrifugal pumps in industrial applica-
tions usually operate over a period of
several decades. The design of the
AHLSTAR pumps 2 aims to minimize
the life cycle costs during the long
expected lifetime. Whereas energy com-
prises the most significant direct cost of
the pump, high reliability and easy main-
tenance help to bring down the indirect
cost. The failure of one pump can stop
the whole chemical processleading to
increased costs and environmental impact
that easily outweigh the lifetime energy
cost of the pump.A design with the goal of achieving
low outage costs for the pump has to
take into consideration two main aspects.
First, a reliable pump design minimizes
the lifetime maintenance costs and
reduces the risk of unscheduled process
interruption. Second, the units must be
designed to be service friendly to shorten
downtime whenever maintenance is
required. One example of this approach
is the innovative impeller mounting,
which allows for easy and quick instal-
| Sulzer Technical Review10 2/2012
POLYMERS
2 Design of the Sulzer AHLSTAR process pump.
What are the challenges of high gas loads?
Gases can be present in liquids in three different states:
Dissolved in the liquid
Bound on the particles contained in the liquid
As free gas in the form of bubblesGas in the form of bubbles disturbs pumping. Gas bubbles
collected in the impeller eye reduce the pump capacity and head.
Pumping becomes very unstable, varies heavily, and requires
excessive overdimensioning of the pump.
Sulzer Pumps has developed pump types, like the AHLSTAR
pumps, which, through their operating principle, remove
disturbing gas or air contained in the liquid so as to maintain
proper pumping. In conventional centrifugal pumps,the free gas accumulates in front ofthe impeller.
AHLSTAR +!a/! 2/$ 1aab! !!
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lation and dismounting of the impeller.
The highly standardized modular design
of the AHLSTAR range facilitates spare
parts service for the large number of
pumps installed all around the world in
different industrial segments.
Minimal environmental impact
All industries must consider the ecological
consequences of their processes and
reduce the impact of those on the envi-
ronment. The Sulzer process pumps sup-
port these efforts with various features.
Reliable shaft seals
of the pump specif-
ically selected for
pumped liquids and
related applications prevent the pumped
liquids from leaking, and reliable shaft
seals of the bearing unit prevent both
the contaminants from coming into con-
tact with lubricant and lubricants from
leaking. The shaft seals of AHLSTAR
require little or no water lubrication and
thus help to further reduce the environ-
mental impact and operation costs.
Recycled metallic materials, reliable
operation, high energy efficiency, as well
as few leaks from shaft sealing and
bearing additionally minimize the envi-
ronmental impact of the units. Further-
more, over 90 % of the metallic material
used for manufacturing the pump can
be recycled at the end of the pumps life-
time.
Innovative and patented pump design
Pumping critical liquids in demanding
applications requires innovative designs.
Various characteristics of the AHLSTAR
pump range are so advanced that Sulzer
has decided to protect them by patent.
Unusual for a mature product such as
a pump, the AHLSTAR features several
patented designs for hydraulics, shaft
sealing, and bearing unit. These patents
ensure reliable and highly efficient oper-
ation for challenging pumping applica-
tions and help to reduce the number
process shutdowns, limit maintenance
needs, and lower energy consumption,
thereby minimizing total life cycle costs.
The excellent flexibility, durability, and
efficiency make the AHLSTAR pumps aperfect choice for the chemical process
industryand especially for polymer
manufacturing. Several key polymer
producers have turned to Sulzer for the
outstanding pumping performance and
extensive experience.
Sulzer Technical Review |2/2012 11
H M5555Sulzer Pumps Finland OyP.O. Box 6648601 KotkaFinlandPhone +358 500 259 737
POLYMERS
Sulzer Pumps has a full-scale laboratory in Kotka, F inland,and can test the final design options in real operational conditions.
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Lorenzo Ghelfi:Jolanda is the masterpiece of our
biopolymer team.
4378
You and your team call the new pilot
plant Jolanda. What can Jolanda do?
With this facility, we can produce the
bioplastic polylactic acid (PLA) on an
industrial scale. Jolanda can produce up
to 1000 tons of PLA a year. The starting
materials for our innovative processes
are dimers of lactic acid, which are
extracted from natural raw materials
such as sugar, starch, or cellulose.
What is so innovative about this
process?
Our polymerization process is character-
ized by the unique mixing technology.
With our static mixer technology and
the SMRplus mixing reactor, we can
considerably shorten reaction time and
nevertheless have very good control over
the entire process. Our competitors are
using processes in which the polymer is
retained in large reactors over much
longer time periods. With the increase
in viscosity during the reaction, the dwell
time in such reactors cannot be controlled
across the complete volume of the tank.
Our facility, on the other hand, is
equipped with numerous, very efficient
heating and cooling zones. As a result,
we can precisely control temperature,
viscosity, and pressure at every stage of
the polymerization process, and we can
thereby achieve the desired product
properties.
How did the idea for the new PLA
process arise?
Sulzer has already accumulated more
than twenty years of experience with
lactic acid and derivatives for the pro-
duction of PLA. At the beginning, our
interest was in the preparation and
cleaning of lactic acid products throughrectification. We then developed the
crystallization technique for lactides.
Sulzer Chemtech strengthened its
expertise in the systems area with the
acquisition of the Khni company in
2009. Cooperation with Puracthe
world leader in lactic acid and lactide
productionand Synbra as our end
customer then led to our PLA activities.
We thereby used our well-tested mixing
and reaction technology as the basis, and
we continued to develop the process
specifically for the production of PLA.
A first, continuous pilot plant in
Winterthur with this new PLA tech-
nology delivered such convincing
results that a contract to build a large
installation at Synbra in Holland came
about within a very short time.
With the new process, our customer
can produce bioplastics with higher
quality and tailor-made propertiesand
that at a price that can increasingly
compete with conventional petrochemical
plastics.
The new pilot plant now opens up
entirely new possibilities. What are the
major benefits for the customers?
The new PLA facility in Pfffikon is larger
and more efficient than the existing pilot
system in our test center in Winterthur.We can now also ensure continuous
operation with the operational concept
of the new plant. We employ nine oper-
ators in three shifts in Pfffikon. In addi-
tion, we work closely with our develop-
ment laboratory in Winterthur, where
our analysis team is based.
The new plant has a variety of
functions. It serves as a demonstration
plant for future customers and makes it
possible to train their employees. It is
also used for productionboth for larger
| Sulzer Technical Review12 2/2012
NTERVIEW
The new Sulzer Chemtech pilot plant for bio-
plastics went into operation in Switzerland in
June. In this interview, the Operational Manager
Lorenzo Ghelfi gives us an insight into the
development and importance of this facility.
Lorenzo Ghelfi presents polymer samples from the new pilot p lant.
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product samples for customers and for
the development of our own formulations
and new PLA products.
Why do customers want a
demonstration of the technology?
Customers invest millions in large-scale
production plants, and want to take on
as little risk as possible on the technical
side. It is therefore understandable that
the customers would like to see our poly-
merization process one-on-one before
they make their investment. With our
new plant, the customers can precisely
check the energy consumption and effi-
ciency of the process, as well as the
quality of the product, well in advance.
The production of samples is also an
important issue for the customers.
Yes, because the customers carry out
their market development in the time
period from the pur-
chase to the comple-
tion of a PLA plant
and there are many
risks in marketing. Before you produce
the corresponding amounts in the kilo-
ton scale in a large plant, there is always
the question of whether the right
products have been selected, whether
the quality meets the requirements of
specific applications and whether
enough end consumers can be found.
Our customers therefore require PLA
samples to be produced in advance, in
order to be able to manufacture and test
end products such as foils or fibers. With
our facility, we can deliver PLA samples
with various formulations in quantities
from 20 to 200 tons and thereby ensure
that the later production and sale runssmoothly for the customers.
Who are your customers?
We have received inquiries from major
plastics producers as well as many
smaller companies who have cost-effec-
tive access to the natural raw materials.
In many countries in Asia and South
America, plants such as sugar cane or
cassava roots are cultivated in large quan-
tities, so that sugar and starch are easily
accessible. The construction of processing
plants or even complete PLA systems
therein the immediate vicinity of the
cultivation areasis particularly attrac-
tive.
More and more companies around the
world are becoming interested in PLA.
What is the reason for this?
Companies increasingly see a strategic
advantage in producing products from
alternative raw materials instead of min-
eral oil. At the moment, almost all the
products in the plastics market are based
on mineral oil and natural gas. The desire
to become independent of rising prices
and the limited availability of fossil fuels
is a major trend.
Is the PLA business also a growth
market for Sulzer?
Yes, we have ambitious goals. The new
PLA technology and our demonstration
plant should considerably increase our
business with polymers. The currently
still smallproportion of polymer
processing technology in the total sales
of Sulzer Chemtech should increase
significantly in the next few years.
You, yourself, have been with Sulzer
for more than 30 years. What experi-
ence do you bring to this project?
What were the greatest challenges?
I bring experience in engineering and
management. Managing a purely chem-
ical production is a new challenge for
me. But thanks to my life and professional
experience, I can comfortably deal withunexpected situations.
It has been particularly challenging
to coordinate the teams from three
locations and to thereby keep to time
and cost schedules. Our colleagues in
Allschwil built the plant. The depart-
ment in Winterthur is responsible for the
engineering, while we in Pfffikon carry
out the assembly. Thanks to the great
dedication of all our employees, we have
been able to overcome all these difficul-
ties.
How would you differentiate this
project from the earlier ones that you
carried out for Sulzer all over the world?
I have worked for Sulzer all around the
globe: in Brazil, Argentina, Russia, and
the USA. This time, in the new project
in Switzerland, there are no difficulties
with regard to cultural and language
differences. However, the official regula-
tions and specifications for work and
environmental protection are dealt with
much more strictly here.
Why has Sulzer Chemtech decided on
the location in Pfffikon? Can produc-
tion be cost effective in the high-wage
country of Switzerland?
Customers from all over the world visit
us and appreciate the proximity to the
sales department of Sulzer Chemtech as
well as the easy accessibility via the
nearby Zurich International Airport.
Switzerland offers an ideal environment
for high-tech industry. Furthermore, we
also benefit from the proximity to our
development department, which supports
us in the operation and optimization of
the plant. This would not be possible at
other locations. And, as we work effi-
ciently following LEAN principles, we
are also competitive at the location
Switzerland.
What is planned for the future?
We are planning to operate Jolanda for
some years in order to establish the new
PLA technology on the market. The sig-
nificant investment in this polymer
system should act as a trigger and lead
to the breakthrough of the technology.
Interview: Tnde Kirstein
Sulzer Technical Review |2/2012 13
INTERVIEW
L6956 Gstudied mechanical engineering at the ZHAW (ZurichUniversity of Applied Sciences), Winterthur, Switzerland.He worked as a project engineer in the field of industrialcombustion technology for metallurgy and power plantconstruction. He has been working for Sulzer Chemtechfor more than 30 years in the fields of internationalsales, project management, and engineering, as wellas the production of process equipment for theinternational construction of chemical plants and oilrefineries. During his foreign deployments in managingpositions in Argentina, Brazil, Russia, and in the USA,he built up new business units for Sulzer and expandedthe global market p resence of Sulzer Chemtech.He recently returned to Switzerland following hisdeployment of several years in Russia and is nowmanaging the buildup and the operation of the polymer
pilot plant in Pfffikon.
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The use of surface coatings or treat-
ments has gained acceptance as a
way to improve tools in the produc-
tion of plastics. Depending on the appli-
cation, different thin-film technologies
are used for wear and corrosion
protection and for the minimization of
friction.
Sulzer Metco is a market leader for
coating services, and it works together
with well-known customers in the
plastics industry. For example, the Coca-
Cola Company in China produces all its
caps with tools that have been coated
by Sulzer Metco. More than 25 % of all
beverage caps in the world are produced
with tools that have been coated by
Sulzer Metco 1. Surface solutions from
Sulzer Metco not only fulfill the high
requirements of the food industry, they
are also used in the demanding pro-
duction of medical engineering products.
Tools that have been coated by Sulzer
Metco produce around 15% of all medic-
inal disposable syringes worldwide.
Wide range of stresses
The surfaces of plastic molds or tools
are subject to many different stresses in
the production process. The major wear
mechanisms in the production of plastics
are:
Corrosion, above all, in the form of
surface and pitting corrosion
Fouling by the smallest particles or
coatings on the tools
Abrasive wear as a result of particles
embedded in the plastic
Cavitation (tool-damaging bubbles
in the plastic material) through local
vapor pressure differences in the
flowing medium
Adhesive interactions
Surface damage when cleaning
the tools
Additives enhance the wear mechanisms.
The additives that are important for plas-
tics can be dyes, plasticizers, or other
More effective manufacturingthrough coated tools
Beverage caps and disposable medical syringes have something in common:
They are produced with tools whose modified surfaces are particularly resistant.
Sulzer Metco has many years of experience in the development of tailor-made
surface coatings and treatments for every kind of loading.
More than 25% of all beverage caps worldwide, including those for Coca-Cola in China, are produced usingtools that have been coated by Sulzer Metco.
Efficient processing of plastics
| Sulzer Technical Review14 2/2012
POLYMERS
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fillings, such as glass fibers or chalk.
They are used to influence component
properties such as strength, elasticity, and
hardness. At the same time, however,
these modified plastics place more load
on the tools during the production
process and increase wear.
A coating or heat treatment of the tools
can reduce the abovementioned wear,
which increases their service life and
reduces the maintenance outlay. At the
same time, a modified tool surface can
significantly reduce production costs by
saving on separators or lubricants.
The right solution for every demand
The thin-film technology division of
Sulzer Metco offers individual solutions
for many different requirements. These
include plasma heat treatments and coat-
ings as well as a combination of the two.
The selection of the appropriate surfacetreatment depends on the plastics and
elastomers to be processed and the
specific parameters of the production
processes.
Improving the surface with heat
Surfaces can be improved with thermo-
chemical heat treatment. The thin-film
division of Sulzer Metco offers its cus-
tomers two process variants of heat treat-
ment:
The patented IONIT OX procedure
gives treated materials excellent
resistance to corrosion and wear, and it
has proven to be an environmentally
friendly alternative to hard-chrome
plating. It is frequently usedeven in
the sensitive food industryand is a
combination of gas nitrocarburization,
plasma-nitrocarburization, and subse-
quent oxidation.
Resistance to wear and friction and
sliding properties can be improved
with the IONIT procedure, which
can also be used for high-alloy steels,
super alloys, and light metals such as
titanium and titanium alloys.
Cost savings are possible in both proce-
dures, above all, through the replacement
of expensive materials. For example, tem-
pered steels, which are considerably
cheaper, can be used in place of stainless
steels.
Proven coatings for the plastics
industry
In coating processes, a distinction is made
between physical vapor deposition
(PVD) and chemical vapor deposition
(CVD). Coatings with thicknesses in the
micrometer range are applied in both
procedures.
The following PVD hard coatings have
proved effective in the area of the plastic
and elastomer processing industry:
Titanium nitride (TiN)
Aluminum titanium nitride (AlTiN)
Chrome nitride (CrN)
Multilayer chrome nitride
Modified chrome nitride layer
(CrNmod) 2.
Sulzer Technical Review |2/2012 15
POLYMERS
Types of heat treatments
The generic term nitriding stands for processes in which the edge regions of ferrous
materials are enriched with nitrogen. If carbon is also supplied at the same time, this
is referred to as nitrocarburation. This process improves the resistance to wear, the
hardness, and the friction and sliding properties of the material. Two subcategories
are differentiated in nitriding:
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PVD and CVD are well-proven coating processes:
In @+ =69 6;65 (PVD), the initial material is
transferred into the gas phase with physical processes and
is condensed onto the component to be coated. Commonly
used variants are vacuum arc evaporation and magnetron
sputtering.
In +4+ =69 6;65 (CVD), material is deposited
onto a component from the gas phase by means of achemical reaction.
| Sulzer Technical Review16 2/2012
POLYMERS
What is PVD and CVD?
Thermoplastic synthetics, such as
polyetheretherketone (PEEK), and elas-
tomers, such as natural rubber, can be
successfully processed. PVD coatings are
also successfully used in the extrusion
of polyethylene (PE) or polypropylene
(PP), among other applications, as well
as on polyethylene terephthalate (PET)
molding tools.
Customer successes demonstrate the
advantages
PVD coatings contribute significantly to
increasing performance and productivity:
In the case of coil distributors coated
with CrNmod for the production of
films from polyvinylchloride (PVC) or
polypropylene (PP), customers have
reported increases in service life of a
factor of 10. The sliding properties of
wide-slit nozzles coated in this way were
also improved by 30 %3
.
Versatile use of carbon coatings
Diamond-like carbon (DLC) coatings
can be applied using the PVD process
or the PACVD (plasma-assisted chemical
vapor deposition) process. The PACVD
process is a plasma-assisted variant of
the CVD process, in which temperatures
are considerably lower and do not
exceed 200 C.
DLC coatings of the type a-C:H (hydro-
gen-bearing amorphous carbon coatings)
are used above all in the plastics industry.
The particularly smooth, amorphous
a-C:H coatings are utilized for optically
high-quality surfaces, for example, in
CD and DVD production.
DLC coatings are also used with great
success on tools in the cosmetics industry4, as well as for ejector pins, cores, and
sliders in injection molding. The benefits
are:
Reduction of scale formation
Excellent wear and corrosion protection,
even at the standard film thickness of
24 microns
2 CrNmod-coated molds are used in the automobile industry.
Prevention of slip-stick effects (these
arise from a reduced difference
between sliding and adhesion friction)
Elimination of burner streaking
Improvement of the flow behavior
of the polymer melt and, thereby, an
increase in the transport capacity
Customers benefit from DLC coatings
Customer examples show how effective
the coating of tools can be: cores for the
manufacture of disposable syringes have
to be cleaned every three to four hours
if uncoated. After a DYLYN/DLC coat-
ing, no cleaning was necessary, even after
one and a half years. Corrosion problems
were also eliminated.
Similar benefits were also seen in
textured blow molds coated with
DYLYN/DLC: instead of regular
reworking in a two-week cycle, produc-
tion without rework could be continued,
even after eight weeks.
Pioneering Psolid diffusion coating
for high-gloss mirror surfaces
The new Psolid diffusion layer represents
one of the most innovative approaches
to tool surfaces in plastic injection
Vacuum pump
Substrate
Gas supply, e.g. CH4
Reactive plasma
Plasma generator
C$D 96+
In the thermal CVD process energy issupplied in form of heat; in the plasma-assisted CVD process, (see figure) agas is excited in a plasma.
1
2
3
4
5
Vacuum measurement andcontrol system
Circular evaporators
Power supplies
Coating chamber
Process gas
Vacuum pump set
Window
Infrared temperaturemeasurement
Substrate holder
BIAS power supply (substrate)
P$D 96+
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2
3
4
5
6
7
8
9
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molding and extrusion molding. Using
this method, a scratch-free passive layer
that has a high resistance to corrosion
and pitting is formed on the surface of
the tools and molds.
The use of a Psolid
coating on corrosion-
resistant steels or
cold-working steels with high chromium
content provides hardening without any
loss in corrosion protection. In the
coating of hot- and cold-working steels
in particular, the diffusion layer creates
tool surfaces with values up to 1600 HV.
With a diffusion depth of 1050 m,
coated components nevertheless remain
constant in size and shape.
Time savings in the production of
high-gloss surfaces
Due to the large outlay in time and the
enormous cost factors when machininghigh-gloss or polished mold surfaces,
savings are urgently sought in the
plastics processing industry. A time
saving for converting a polished surface
to a high-gloss surface is possible thanks
to Psolid. The wear-resistant coating pro-
tects against adhesion, considerably
reduces deposits, and facilitates mold
cleaning. Visible defects in the plastic
parts can be excluded, as the layer neither
flakes nor becomes brittle.
Users in the plastics-processing in-
dustry, polishing companies, and tool
manufacturers profit from the consider-
able advantages of a Psolid coating 5.
The time savings reduce production and
repair costs dramatically, while simulta-
neously providing a considerable
improvement in the uptime of the tools.
Advantages of combined treatment
The combination of plasma nitration
with subsequent coating using PVD or
PACVD combines the advantages of both
types of surface treatment. Steels that
contain proportions of special alloying
elements (chrome, aluminum, vanadium,
molybdenum) can achieve high surface
hardness and represent an excellent basis
for the subsequent coating. The mechan-
ical properties of the material core, such
Sulzer Technical Review |2/2012 17
POLYMERS
3 Nitrided wide-slot nozzles are coated inthe Sulzer installation.
4 DLC-coated components are used in the manufacture of cosmetic pencils.
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5 Matrix blocks for the manufacture of disposable syringes havecavitation holes on the inside. These cannot be coated with traditionalcoatingswith P.+(%, it is unproblematic.
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as toughness and crack resistance, remain
unchanged.
With the combined treatment, the load-
bearing capacity of the surface is deci-
sively improved, so that the infamous
eggshell effect does not occur (see
infobox).
In the processing of glass-fiber-rein-
forced polymer materials, these kinds of
hardened tool surfaces prevent the added
hard additives from being pressed into
the tool surface at high process pressures.
In plastics processing, the tools have
to be cleaned at the latest during a pro-
duction change. Polymer residues are
thereby usually removed using scrapers
and spatulas made from steel, which
can easily lead to damage to the surface.
This damage can be avoided through
the supportive effect of nitriding.
Sulzer Metcoa strong partner for
coating solutions
In the field of thin-film technology, Sulzer
Metco has service centers worldwide for
the contract treatment of tools and com-
ponents. In addition to services for
surface improve-
ment for various
industrial and appli-
cation areas, its own
system construction division delivers
innovative new developments and
further developments through its own
research and development work. The
service teams have many years of expe-
rience in dealing with plastic tools. The
members of staff make use of their exten-
sive experience in the industry to provide
the clients with targeted consultation.
A special feature is the contract treat-
ment of long and large parts. The max-
imum dimensions for large-volume parts
are: 1800mm long, 1500mm diameter,
and 3.18m3 total volume. Furthermore,
extruder screws or wide-slot nozzles up
to lengths of 4500mm, diameters up to
600mm, and volumes of 1.27 m3 can be
treated 6.
| Sulzer Technical Review18 2/2012
POLYMERS
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The most highly developed examplesof the natural silk technique are thewebs of cross spiders and other orb-
weaving spiders. They construct a
vertical, two-dimensional web between
two anchor points that are relatively far
apart. Starting from a first, bridging
can thereby cushion the impact of the
collision. If the stretched thread were to
then spring back to its original position
like a rubber rope, the insect would be
catapulted back into freedom as if from
a trampoline. But because the web
returns only gently after the rapid expan-
sion, the prey remains caught. The trick
lies in the sticky water drops. The silk
thread is rolled up on the drops through
the surface tension of the liquid. The
resulting numerous loops cause, like a
cable reel, both the rapid extension and
the braked rerolling of the thread.
A targeted mix of amino acids
The silk technique of the cross spider is
also amazing because, in its abdomen,
the animal carries a selection of seven
different silk glands, which lead into a
complete battery of spinnerets. Depending
on the function of the thread, it is
produced with a special mixture of amino
acids for a specific thickness and
elasticity. For example, there are different
silk materials for the frame and the
spokes, for the auxiliary spiral, the catch-
ing spiral, or the glue for linking and
attaching the threads.
The thread itself also has a sophisticated
design. Although still a liquid made upof keratin molecules in the silk glands,
the protein mass transforms itself within
milliseconds when squeezed through the
narrow valve of the silk gland. Strong
shear forces compel the keratin to take
on a specific structure: A part of the
protein folds like the bellows of an accor-
dion to form solid crystals, while the
rest encases the crystals as disordered
molecule chains, like a ball of spaghetti.
A thread that is both elastic and extremely
tough results from this procedure. The
tensile strength of spider silk is around
2500kg/cm2. Relative to its weight, it is,
therefore, five times stronger than steel.
Medical and musical applications
In order to be able to make use of spider
silk technology, the genes involved have
been isolated recently and have been
introduced into bacteria for silk produc-
tion. Possible product applications are
artificial tendons and ligaments, bandages,
or fabrics for bulletproof vests. There is
a great deal of interest now in the devel-
opment being done by the Japanese pro-
fessor for polymer chemistry Shigeyoshi
Osaki. Thousands of threads from the
spider species Nephila maculata have
been woven into compact strands that
can now be used as violin strings. After
the first trials, violinists highly praised
the soft and full tones of the silk strings.
With their silk glands, spiders produce a silk material withexceptional properties.
thread, the spider constructs the basic
framework of the orb web with edge
threads and spokes and, finally, the catch-
ing spiral by means of an auxiliary spiral.
Any insect that hits the web will become
caught on this catching spiral through achain of extremely sticky pearl-like drops
made up of water and glycol proteins.
Gently catching a bomber
The web that catches the insects has to
cope with an enormously challenging
task. If, for example, a large fly hits one
of the one-thousandth-of-a-millimeter-
thick threads, it is like a bomber, and
the impact should actually break the web.
However, the silk threads can stretch to
up to five times their original length and
4375
Spider silk as a superpolymerMacromolecules are formed by the polymerization of base molecules and
form the basis of life. For example, proteins consist of thousands of amino
acids, and nucleic acids build up the genetic code from millions of nucleotides.
Spiders have an amazing technique for building complex spatial structuresfrom protein chains.
Sulzer Technical Review |2/2012 19
SULZER ANALOGY
Spider silk is a wonder of nature and can even
improve the sound of violins.
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Sulzer Innotec supports the Sulzer
divisions and external clients in
polymer analyses with its modern
laboratory and its many years of
expertise in plastics. The following
project examples from Sulzer Innotec
show that many factors (such as material
composition, component manufacturing,
and operating conditions) have to be
taken into account in polymer analysis
in order to uncover the causes of short-
comings and to find adequate solutions
for them.
Case 1: What kind of constituents are
in the plastic?
As a result of globalization, polymer
materials and, in particular, high-perfor-
mance plastics that supposedly have
the same composition are available from
various manufacturers. The price of
the material plays a central role in the
choice of the supplier. The selection is
still not easy, however, because the
quality differences are often not recog-
nizable at first glance. In order to ensure
that the component quality remains
the same, even following a change of
supplier, it is recommended that buyers
carry out a detailed analysis of the
Following the trail of polymeric evidencePlastics are being used more and more frequently in modern machinery and equipment
design because they are light, resistant to corrosion, and cost effective. In order to
obtain optimal plastic properties, technological analyses are essential. Due to the many
influencing factors and complex issues, however, the interpretation of results requires
extensive knowledge and, in many cases, detective-like instincts.
Micrographs clearly illustrate how plastics are composed of different constituents(thin section under polarized light).
Polymer analysisbetween measurement and interpretation
| Sulzer Technical Review20 2/2012
POLYMERS
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replacement material in advance.
Deficiencies occurring in operation
can thereby be avoided from the very
start.
Comparing suppliers
For an external client, Sulzer Innotec
compared carbon-fiber-reinforced modi-
fied PEEK materials from two different
suppliers. For the end product, which
is subjected to high mechanical and
tribological loads, the client wanted to
replace the feedstock pellets from
supplier A with the cheaper pellets from
supplier B. Sulzer Innotec was asked
to determine whether or not the main
components of the two materials were
qualitatively and quantitatively the same.
To start with, standard laboratory test
methods were applied to the problem:
Fourier transform infrared spectro-
metry (FTIR)
Thermoanalysis:
Differential scanning calorimetry
(DSC)
Thermogravimetric analysis (TGA)
Dynamic mechanical analysis (DMA)
Optical microscopy
The results of the FTIR analyses
showed an optimal match with the data-
base spectrum of PEEK for both feedstock
pellets A and B. No indication of the
supposed PTFE lubricant (Teflon) was
found in either feedstock by means of
FTIR. The results of the thermoanalytical
investigations also revealed no obvious
differences between the pellets from the
two suppliers. The two temperature
peaks at approx. 21C and 330 C for
the two materials clearly indicated the
presence of PTFE, however. With addi-
tional investigations (thermogravimetry
and optical microscopy), the relative pro-
portions of PEEK,
PTFE, carbon fiber,
and graphite could
be determined. The
comparison between
the two feedstocks also showed no
differences here.
The same, but not the same
According to the analyses, the pellets
from the two suppliers should have been
able to be processed into end products
with equivalent properties. However,
although the qualitative and quantitative
composition of the two materials was
shown to be the same and although the
fabrication of the end products was
carried out using the same processing
parameters, the resulting products made
using feedstock B exhibited suboptimal
properties: These parts exhibited sliding
behavior deemed insufficient for the
intended application.
The material analysts from Sulzer
Innotec were able to discover the cause
of this discrepancy. Thanks to scanning
electron microscopy (SEM) of the two
Sulzer Technical Review |2/2012 21
POLYMERS
1 Only in the scanning electron micrographs can a difference be seen between the pellets: The PTFE filler(light color) in material A (left) has a different distribution from that in material B (right).
Plasticsa mix of individual components
As a rule, polymer materials are available in the form of feed-
stock pellets, which are processed further using extrusion or
injection-molding processes. Polymeric base materials in-
clude, for example, polyethylene (PE), polyamide (PA), and
polyetheretherketone (PEEK). In order to meet the detailed
performance requirements for the finished parts, various ad-ditives are mixed together with the base material in a com-
pounding process.
The finished feedstock is therefore the mix of:
The base polymer
Processing aids
Reinforcing agents
Aging and flame retardants
Dyes and other materials
The composition of the feedstock material is part of the
know-how of the respective material manufacturer and is a
closely guarded secret due to the development work that
went into it.
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A change in the processing parameters has many consequences
As the market for the plastics-processing industry is very competitive, many
manufactures try to save costs in the processing of polymer materials. As a result
of variations in the processing parameters (pressure, temperature, speed), it is
possible to make plastic components with very different properties from the same
materials on the same production line.
However, changes in the processing parameters and/or reductions in the cycletimes can affect the quality of the end products. It is not uncommon for problems
to arise with plastic parts that are subjected to high stress. This can have conse-
quences for the part, particularly during long-term operation.
pellet types, they were able to detect sig-
nificant microscale differences between
the two materials. While in feedstock A,
the PTFE phase (light-colored in Fig.1)
was relatively evenly distributed and
took on a spherical form, in feedstock B,
the PTFE component appeared as locally
concentrated agglomerates looking some-
thing like popcorn.
The difference concerning the appear-
ance of the PTFE can be traced back to
the use of different types of PTFE in the
two feedstocks. With this knowledge, the
poorer sliding properties could be con-
clusively explained, and consequently
the client decided against a change of
supplier.
Case 2: How is the plastic processed?
A change in the process parameters can
save manufacturing costs, but can also
negatively affect the component quality.
In order to detect deficiencies in quality,
material analysts use test methods that
react sensitively to changes in the pro-
cessing parameters. Using modern sim-
ulation programs programs to model the
filling behavior or temperature and stress
distributions, the manufacture of plastic
components can be visualized and the
processing can be effectively optimized.
With some components, such as trans-
parent plastics, it is easy to reveal unfa-
vorable processing parameters 2. It is
more difficult to analyze the processing
parameters of long-life components of
high-performance plastics, as the follow-
ing case shows.
A smaller temperature peak provides
the first clue
Sulzer Innotec investigated two oil
scraper rings that behaved completely
differently under the same operating con-
ditions3
. While one worked flawlessly,massive breakout was found on the
scraper edges of the other after only a
short operating time. The measurement
results for both components yielded
almost identical melting curves. Only a
small peak between 200 C and 230C,
which occurred at a higher temperature
in the thermogram of the defective com-
ponent, indicated a small difference
between the thermoanalytical results of
the analyses of the two components. For
the materials analyst, this inconspicuous
| Sulzer Technical Review22 2/2012
POLYMERS
2 The images of the polystyrene lid taken under polarized light reveal residual stressesin the material, which stem from the manufacturing process.
Injection point
Discoloration resultingfrom residual stress.
20mm
free of damage
defective
3 Two identically manufactured oil scrapers made of PPS behave completely differently in operation.
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difference was a first clue answering the
question as to whether the breakout was
due to the composition of the material,
the processing, or the operating condi-
tions.
Inadequate predrying led to brittleness
In the case of the scraper, the detected
anomaly could be definitively assigned
to the processing procedure. Further
investigations showed that the starting
material of the brittle scraper did, indeed,
have the same composition, but that the
material had been insufficiently predried
before it was processed. Due to the
residual moisture that was present, the
manufacturer had to change the pro-
cessing parameters in order to produce
scrapers that were optically perfect. This
change resulted in the detected, higher
peak temperature of the brittle, failed
scraper. As this example shows, the pro-
cessing of the components must also be
taken into account when explaining defi-
ciencies in end products.
Case 3: What happens to the plasticin the operation?
The analysis of damage caused in oper-
ation is challenging because of the many
influencing factors which need to be con-
sidered. Seals and O-rings in heavy-duty
applications represent typical examples
of this kind of question. Component per-
formance is not only a question of the
seal geometry and the temperature-
dependent mechanical properties of the
material, but also of the thermochemical
processes that occur in operation. A quick
on-site assessment of the situation is dif-
ficult, because the causal factors influence
each other and are not obvious.
Sulzer Innotec investigated defects in
the seals of water-cooled engines, for
which silicone O-rings were used.
According to the
data sheet from the
material manufactur-
er, the silicone used
is resistant to water
and steam at operating temperatures
below 130C. However, leaks in the seals
were detected after an operational period
of only six months 4.
Specialists from Sulzer Innotec
assessed the seal geometry and the
O-ring groove on site and found
them to be in order, but detected massive
damage to the O-rings themselves 5.
The deformation of the O-rings and
the numerous cracks along the entire
circumference indicated the occurrence
of a thermal degradation process. Labo-
ratory tests on unused O-rings were able
Sulzer Technical Review |2/2012 23
POLYMERS
4 First on-site inspections provide only few indications of the causes of defects(e.g., at these O-ring seals in a water-cooled engine).
Analysis of damage caused in operation
A number of factors can lead to the failure of plastic parts in operation:
Mechanical stresses (time- and temperature-dependent creep and relaxation
processes)
Thermal stresses
Chemical stressesAs these three factors are interdependent, it is not enough to assess their
operational impact individually. The analysis is made more difficult by the complex
and secret compositions of the plastic compounds. In particular when installing off-
the-shelf plastic components, it is not possible to judge whether or not both the
material and the processing were correct. It is therefore challenging to interpret the
analysis results correctly and to attribute them to the operating conditions where
necessary.
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to show that both material and manu-
facturing quality could be excluded as
causes of the failure.
Moisture and heat decompose the
plastic
More-detailed analyses finally led the
analysts at Sulzer Innotec onto the right
track: The damage
to the O-rings was
due to a chemical
decomposition of the
silicone as a result of the conditions expe-
rienced in operation. The cause was a
damp environment (hydrolysis) at a tem-
perature that was too high (significantly
above 130 C). Consequently, the macro-
molecules of the O-ring material were
being split chemically, resulting in short-
ened molecular chains and the consequent
embrittlement of the material. The degen-
eration process could be reproduced in
laboratory trials, since degradation also
occured without the mechanical loading
typically experienced in operation 6.
The client had two options available
based on this result: Either reduce
the operating temperature in the area
of the O-rings to below 130 C, or replace
the silicone with a more suitable
elastomer material. Using aging trials
developed and performed out in-house,
Sulzer Innotec was able to narrow
down the choices and recommend the
best-possible sealing material 7. Follow-
up checks on the seals in use confirmed
the good results from the laboratory.
Based on the results from Sulzer Innotec,
a major material change to a special
fluoroelastomer was initiated.
It is the right interpretation
that matters
As the above examples show, it is not
simply performing the measurements
themselves that is difficult in plastics
analyses; the interpretation of the meas-
urements requires almost detective-like
instincts. It is particularly challenging
when it is not possible to precisely
analyze all the required parameters.
In order to be able to draw the right
conclusions in complex issues, inter-
disciplinary expertise in the area of
plastics technology, in addition to
close and open-minded cooperation
with the client and extensive experience
in polymer analysis, is decisive for
success.
G5;9 D959Sulzer InnotecSulzer-Allee 258404 WinterthurSwitzerlandPhone +41 52 262 69 41
| Sulzer Technical Review24 2/2012
POLYMERS
10mm
7 Aging trials for the selection of a suitable sealing materialwere carried out in the laboratory.
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Sulzer Metco has a modern and growing
location for diamond-like carbon coatings
(DLC) in Limoges, France. These coatings
are particularly suited for use in automotive
applications and motor sports.
Sulzer Technical Review |2/2012 25
SULZER WORLD
4381
The location in Limoges isworld-famous in motor sports for
diamond-like carbon coatings.
T
hrough the acquisition of Bekaerts
DLC division in 2010, Sulzer Metco
expanded its technology portfolio in the
area of thin-film surface coating. The
location in Limoges that is involved in
this field has a long history of success
with DLC coatings. The first engines
were coated with DLC here as long ago
as 1995, and the location has experienced
active growth in the meantime. This is
especially evident from the numerous
expansion activities in the production
halls in the last few years. Clients can
be sure that the 65 employees at the loca-
tion will guarantee the very best quality
at all times.
Established in motor sport
growing in new markets
DLC coatings such as CAVIDUR and
DYLYN are characterized by their espe-
cially smooth textures. At the same time,
they display low coefficients of friction
and a very high resistance to wear. It is
for exactly this reason that they are par-
ticularly suitable for use in motor sport,
where every millisecond is crucial.
Formula 1 teams worldwide are equipped
with DLC coatings. At the Limoges site,
the majority of the business is generated
in motor sport. Significant and steady
growth can, however, also be seen in the
fields of plastics, automobiles, engineer-
ing, and metalworking. Surface solutions
for the semiconductor industry are also
being offered in increasing numbers.
The highest standards for
equipment and control
Limoges has a modern, fully automated
cleaning line that meets all customer
requirements. Eleven coating installations
are currently in continuous operation.
These include DLC coating installations
and a PVD (physical vapor deposition)
system. In particular, Limoges is able to
guarantee a high quality of production
through its cleanroom. A special feature
of the Limoges site is the final inspection
at the end of the coating process: visual
inspections as well as additional mechan-ical and computer-supported analyses
in some cases with equipment developed
inhouse for large componentsensure
the highest quality of the end products.
Center of excellence and coopera-
tion with universities
In order to be able to guarantee state-
of-the-art coating solutions for clients,
the site also operates an R&D system.
Coatings that have been modified
and further developed can be tested
under realistic production conditions,
which makes the rapid transition to a
sustainable production process particu-
larly easy.
In addition, Limoges is currently
working together with the University of
Limoges and leading partners from the
automobile industry on a research project
that will set new standards with its
DYLYN coatings. The proximity of the
location to the university, which is only
500 meters away, facilitates the continuous
cooperation with qualified students and
institutes.Sulzer Metco in Limoges stands out
through its impressive diversity. In addi-
tion to modern coating installations and
high-tech equipment, the expert knowl-
edge of the employees is just as important
as the wide competence network with
industry and research. Through the expe-
rience and the broad-based expertise of
the employees in Limoges, Sulzer can
continue to grow internationally and
expand its position as a technology
expert.
Welcome to Sulzer Metcoin Limoges
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Finding defects in turbine blades is
one important task of the lock-in
thermography setup at Sulzer Turbo
Services 1. An ultrasound transducer
introduces elastic waves (propagating
elastic deformations) into the turbine
component. In homogeneous material,
the reflected waves are evenly distributed.
However, at locations where the alloy is
damaged, some of the wave energy is
absorbed, and heat is generated. This
heat has a different infrared (IR) radiation
than its surrounding area and is detected
by the IR camera 2 (see infobox).
Infrared images reveal defects
Modulation of the ultrasonic wave
improves the heat contrast and provides
an amplitude image and a phase image
of the turbine component. The amplitude
image is a measure for the temperature
and is related to the thermal diffusivity.
The phase image reveals the size and
depth of the defect. The phase is a result
of a shift in the output signal with respect
to the input signal and is related to the
propagation time or depth.
Insightful hot spotsLock-in thermography is a versatile inspection method capable of identifying
defects in gas turbine parts. Sulzer Turbo Services Venlo uses this advanced
method not only to examine turbine components, but also as an R&D instrument
to improve turbine design and repair to the benefit of the customers.
1 Sulzer Turbo Services Venlo uses ultrasonic thermography for turbine inspection and research.
Thermographic inspection of industrial gas turbine components
| Sulzer Technical Review26 2/2012
PANORAMA
1
2
3
1 2
3
IR camera
Turbine part
Ultrasonic transducer
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PANORAMA
3 The results of a thermography inspection show damage to a turbine blade.The magnified image on the top shows an internal crack; the magnified imageon the bottom shows a crack on the surface.
Thermographic inspection
In thermographic inspection, an infrared
(IR) camera measures and visualizes the
heat distribution within an object.
There are two approaches:
In = ;9469@, the exist-
ing thermal radiation of an object is
measured. Common applications are
the detection of insulation faults inhousing, detection of overheating in
power supply stations, and level
detection in storage tanks.
A+;= ;9469@ introduces
energy into the object and measures
the objects response. One method
is lock-in thermography, which uses a
transducer to introduce ultrasonic
waves into the object.
2 The detectionprinciple of lock-in thermographyis based onultrasonic wavesthat generateheat at damagedlocations insidethe turbine part.
The bright spots in the phase image
need to be inspected in more detail in
order to determine whether the hot spot
is a real defect. For this reason, the
sequence profilewhich is the amount
of radiation measured on one spot in
timeis analyzed. The sequence
profile of a defect is different from the
profile of other surrounding heat sources,
for example, the reflection of a lamp.
A defect shows a response curve similar
to the modulation frequency of the
excitation.
Distinguishing between internal and
external defects
Sulzer Turbo Services Venlo applies lock-
in thermography to identify structural
defects in turbine parts. Such defects
include cracks along the grain boundary
that have been caused by corrosion, oxi-
dation, mechanical stresses, or casting
defects.
Because turbine parts are made of
metal alloys, the heat signature generated
is not just limited to the defect itself. Theheat is conducted and creates a slightly
weaker hot spot that is larger than the
defect itself. The advantage of this
thermal conduction is that the heat sig-
nature of internal defects is detectable
as a diffuse heat source at the surface.
Thus, ultrasonic lock-in thermography
can detect both external as well as
internal defects. Figure 3 shows the
detection of cracks on the surface and
inside of a blade. This method has
significant advantages over other
approaches. For instance, fluorescent
penetrant inspection cannot detect inter-
nal defects and borescopic inspection is
time consuming.
Evaluating coatings with thermography
Ultrasonic lock-in thermography can
also detect a lack of proper bonding
between the parts and their metallic coat-
ing. The elastic waves cause vibration in
the part. If the coating is bonded properly
to the base material, no friction heat is
observable. Friction between the part and
the poorly bonded coating creates a
bright thermal signature. Recently, ther-
mographic inspection has been compared
with conventional manual ultrasonic
inspection with a probe, and a 100 %
match of observed indications has been
achieved.
FFT
IR camera
Turbine blade with defect
Phase image
Amplitude image
Elastic wave
Thermal wave
Ultrasonic excitation Lock-in frequency
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Detection of blocked cooling channels
For turbine components, cooling is very
important to extend and protect compo-
nent life 4. During the repair of vanes
or blades with cooling channels, it must
be ensured that all cooling holes are open.
An IR camera can show at a glance
whether cooling
holes are blocked
or open. This is
achieved by blowing
warm air through the component. A ther-
mal image of the part is recorded in
order to visualize the heating of the com-
ponent. Figure 5 shows an example of
such a recording. Open cooling holes
appear in bright yellow because of the
heating by the warm air. Blocked cooling
channels are not heated; they appear as
a blue-black color.
Research on the efficiency of cooling
holes
Sulzer has started a research project in
order to develop a method of evaluating
the efficiency of cooling channels of tur-
bine blades and vanes. The results of
this project will provide more information
about how the cooling-hole geometry
affects the cooling efficiency.
The research is based on a heat transfer
model that has been developed by the