MatHandling[1]

8/2/2019 MatHandling[1]

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ME 486 - Automation

Materials Handling Ed Red


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ME 486 - Automation

To review modern technologies for material handling:

- Part handling

-AGVs

- AS/RS

- conveyors

To consider application conditions (student presentations)

To introduce assessment criteria

To test understanding of the material presented

Objectives


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ME 486 - Automation

Material handling principles

Principle 1 - PLANNING PRINCIPLE:All material handling should be the result of adeliberate plan where the needs, performance objectives, and functional specification

of the proposed methods are completely defined at the outset.

The plan should be developed in consultation between the planner(s) and all who will

use and benefit from the equipment to be employed.

Success in planning large-scale material handling projects generally requires a team

approach involving suppliers, consultants when appropriate, and end user specialists

from management, engineering, computer and information systems, finance, and

operations.

The plan should promote concurrent engineering of product, process design, process

layout, and material handling methods as opposed to independent and sequential

design practices.

The plan should reflect the strategic objectives of the organization as well as the more

immediate needs.

( from Groover )


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ME 486 - Automation

Principle 2 - STANDARDIZATlONPRINCIPLE:Material handling methods,

equipment, controls, and software should be standardized within the limits of achieving

overall performance objectives and without sacrificing needed flexibility modularity,

and throughput.

Standardization means less variety and customization in the methods and equipmentemployed.

Standardization applies to sizes of containers and other load forming components as

well as operating procedures and equipment.

The planner should select methods and equipment that can perform a variety of tasksunder a variety of operating conditions and in anticipation of changing future

requirements.

Standardization, flexibility, and modularity must not be incompatible.

Material handling principles ( from Groover )


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ME 486 - Automation

Principle 3 - WORK PRINCIPLE:Material handling work should be minimized without

sacrificing productivity or the level of service required of the operation.

The measure of material handling work is flow rate (volume, weight, or count per unit

of time) multiplied by distance moved.

Consider each pickup and set-down, or placing material in and out of storage, as

distinct moves and components of the distance moved.

Simplifying processes by reducing, combining, shortening, or eliminating unnecessary

moves will reduce work.

Where possible, gravity should be used to move materials or to assist in their

movement while respecting consideration of safety and the potential for product

damage.



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ME 486 - Automation

Principle 3 - WORK PRINCIPLE:Material handling work should be minimized without

sacrificing productivity or the level of service required of the operation.

The Work Principle applies universally, from mechanized material handling in afactory to over-the-road trucking.

The Work Principle is implemented best by appropriate layout planning: locating the

production equipment into a physical arrangement corresponding to the flow of work.

This arrangement tends to minimize the distances that must be traveled by the

materials being processed.



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Principle 4 - ERGONOMIC PRINCIPLE:Human capabilities and limitations must be

recognized and respected in the design of material handling tasks and equipment to

ensure safe and effective operations.

Ergonomics is the science that seeks to adapt work or working conditions to suit theabilities of the worker.

The material handling workplace and the equipment must be designed so they are safe

for people.

The ergonomic principle embraces both physical and mental tasks.

Equipment should be selected that eliminates repetitive and strenuous manuallabor

and that effectively interacts with human operators and users.




Principle 5 - UNIT LOAD PRINCIPLE:Unit loads shall be appropriately sized and

configured in a way which achieves the material flow and inventory objectives at each

stage in the supply chain.

A unit load is one that can be stored or moved as a single entity at one time, such as a

pallet, container, or tote, regardless of the number of individual items that make up theload.

Less effort and work are required to collect and move many individual items as a

singleload than to move many items one at a time.

Large unit loads are common in both pre- and post-manufacturing in the form of raw

materials and finished goods. Smaller unit loads are consistent with manufacturing strategies that embrace operating

objectives such as flexibility, continuous flow and just-in-time delivery. Smaller unit

loads (as few as one item) yield less in-process inventory and shorter item throughput

times.




Principle 6 - SPACE UTILIZATION PRINCIPLE:Effective and efficient use must be

made of all available space.

Space in material handling is three-dimensional and therefore is counted as cubicspace.

In storage areas, the objective of maximizing storage density must be balanced against

accessibility and selectivity.

When transporting loads within a facility, the use of overhead space should be

considered as an option. Use of overhead material handling systems saves valuable

floor space for productive purposes.




Principle 7 - SYSTEM PRINCIPLE:Material movement and storage activities should be

fully integrated to form a coordinated, operational system that spans receiving,

inspection, storage, production, assembly, packaging, unitizing, order selection,

shipping, transportation, and the handling of returns.

Systems integration should encompass the entire supply chain, including reverse

logistics. It should include suppliers, manufacturers, distributors, and customers.

Inventory levels should be minimized at all stages of production and distribution while

respecting considerations of process variability and customer service.

Information flow and physical material flow should be integrated and treated as

concurrent activities.

Methods should be provided for easily identifying materials and products, for

determining their location and status within facilities and within the supply chain, and

for controlling their movement.




Principle 8 - AUTOMATION PRINCIPLE:Material handling operations should bemechanized and/or automated where feasible to improve operational efficiency,

increase responsiveness, improve consistency and predictability, decrease operating

costs, and eliminate repetitive or potentially unsafe manual labor.

In any project in which automation is being considered, pre-existing processes and

methods should be simplified and/or re-engineered before any efforts to installmechanized or automated systems. Such analysis may lead to elimination of

unnecessary steps in the method. If the method can be sufficiently simplified, it may

not be necessary to automate the process.

Items that are expected to be handled automatically must have standard shapes and/or

features that permit mechanized and/or automated handling.

Interface issues are critical to successful automation, including equipment-to-

equipment, equipment-to-load, equipment-to-operator, and in-control communications.

Computerized material handling systems should be considered where appropriate for

effective integration of material flow and information management.




Principle 9 - ENVIRONMENTAL PRINCIPLE:Environmental impact and energy

consumption should be considered as criteria when designing or selecting alternative

equipment and material handling systems.

Environmental consciousness stems from a desire not to waste natural resources and to

predict and eliminate the possible negative effects of our daily actions on the

environment.

Containers, pallets, and other products used to form and protect unit loads should be

designed for reusability when possible and/or biodegradability after disposal.

Materials specified as hazardous have special needs with regard to spill protection,

combustibility, and other risks.




Principle 10 - LIFE CYCLE COST PRINCIPLE:A thorough economic analysis should

account for the entire life cycle of all material handling equipment and resulting systems.

Life cycle costs include all cash flows that occur between the time the first dollar is spent

to plan a new material handling method or piece of equipment until that method and/orequipment is totally replaced.

Life cycle costs include capital investment, installation, setup and equipment

programming, training, system testing and acceptance, operating (labor, utilities, etc.),

maintenance and repair, reuse value, and ultimate disposal.

A plan for preventive and predictive maintenance should be prepared for the equipment,

and the estimated cost of maintenance and spare parts should be included in the economic

analysis.




Principle 10 - LIFE CYCLE COST PRINCIPLE:A thorough economic analysis should

account for the entire life cycle of all material handling equipment and resulting systems.

A long-range plan for replacement of the equipment when it becomes obsolete should be

prepared.

Although measurable cost is a primary factor, it is certainly not the only factor in

selecting among alternatives. Other factors of a strategic nature to the organization and

that form the basis for competition in the market place should be considered and

quantified whenever possible.




Automated Guided Vehicle (AGV)

Definition- An AGV is an independently operated vehiclethat moves material along defined paths between defined

delivery points or stations. Typically the paths are defined

by either using wires embedded in the floor or reflecting

paint strips on the floor.

Some of the more advanced

technologies use lasertriangulation or inertial guidance

systems on-board the vehicles,

with distributed calibration

stations for position updating.



AGV classification

Driverless trains - AGV is a towing vehicle used to tow one or more trailers

forming a train between stations.

Pallet trucks - Used to move palletized loads along predetermined routes.

Typically, personnel will steer the AGV to the pallet, acquire the pallet, then

steer it to the guide-path where the automated guidance system will then

move it to its destination. In a sense, it can be thought of as an automated

forklift.

Unit load carriers - Move unit loads from from one station to another

station. A unit load is a collection of items that is delivered repetitively as a

unit.



AGV applications

Driverless train operations - Movement of large material quantity over large distances

(between buildings, warehouses).

Storage/distribution systems - Uses unit load carriers and pallet trucks to transfer material

between stations, sometimes interfacing with other automated systems such as an AS/RS

(Automated Storage and Retrieval System). Works well in assembly operations where theunit loads (or kits) can be transferred from a central storage area to assembly sites.

Assembly line operations - AGVs become part of the assembly operation by transferring

material along an assembly line (such as moving an engine block between operational

stations)

Flexible manufacturing systems (FMS) - AGVs are used to transfer parts, materials andtooling between the FMS process stations.

Miscellaneous applications - Non-manufacturing applications include the handling of

sensitive waste, transportation of material at hospitals, mail transportation.


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ME 486 - Automation

AGV material handling analysis

Equations:

del cycle time Tc = TL + TU + Ld / vc + Le / ve (min)

available time AT = 60 A TfE (min/hr/veh)

rate of del per vehicle Rdv = AT / Tc (num del/hr/veh)

work by handling system per hr WL = RfTc (min/hr)

num of vehicles for workload nc = WL/AT = Rf/ Rdv (num of veh for work load)


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ME 486 - Automation

AGV example (from text)

Given the AGV layout in the figure and the info listed,determine the number of vehicles required for a

delivery (flow) rate of 40 del/hr.

Info:

Loading time = 0.75 min Unloading time = 0.5 min

Vehicle speed = 50 m/min Availability = 0.95

Traffic factor = 0.9 (from fig) =>Ld = 110 m ; Le = 80 m

E = 1

Solution:

Ideal cycle time/del/veh = Tc = 0.75+ 0.5+ 110/50 + 80/50 = 5.05 min

Compute workload = WL = (40) (5.05) = 202 min/hr

Available time = AT = (60) (0.95) (0.90) (1.0) = 51.3 min/hr/veh

Num of vehicles = nc = 202/51.3 = 3.94 veh => 4 vehicles!


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ME 486 - Automation

AGV questions

Who are major vendors of AGVs?

Describe their components (power source, transmission system,

communication system, etc.)?

What are typical costs?

What type of interfaces do they have? How are they programmed?

How fast do they move?

What are load to weight ratios?

Unusual maintenance requirements?

How do they avoid collisions?

How are they scheduled?


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ME 486 - Automation

AS/RS classification

Unit load AS/RS - Large automated system designed to use S/R machines to

move unit loads on pallets into and out of storage racks.

Mini-load AS/RS - Smaller automated system designed to move smaller

loads into and out of storage bins or drawers.

Man-on-board AS/RS - Uses personnel to pick items from racks or bins,

reducing transaction time.

Automated item retrieval system - Items to be moved are stored in single

file lanes, rather than in bins or drawers.


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ME 486 - Automation

AS/RS applications

Unit load storage and handling - Warehousing for finished goods/products.

Order picking - Used to store and retrieve materials in less than full unit

load quantities, such as man-on-board or mini-load applications.

Work-in-process - Support just-in-time production activities, buffer storage,

and as integral part of assembly systems.


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ME 486 - Automation

AS/RS control

The S/R is a large Cartesian type robot that integrates

modern control technology, I/O, and sensors

(compartment identification) to move between storage

compartments. AS/RS control is integrated with modern

material management software for real-time inventorycontrol, storage transactions, and material delivery.


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ME 486 - Automation

AS/RS material handling analysisTerms:

Ccapacity per aislex - width of unit load

y - length of unit load (in horizontal direction)

z - height of unit load (in vertical direction)

nz - number of vertical compartmentsny - number of horizontal compartments

U - system utilization per hr

W - width of AS/RS rack

H - height of AS/RS rackL - length of AS/RS rack

vz - vertical speed (m/min, ft/min)vy - horizontal speed (m/min, ft/min)

tz - vertical travel time (min)

ty - horizontal travel time (min)

Tcs - single command cycle time (min/cycle)Tcd - dual command cycle time (min/cycle)

Tpdpickup and deposit time (min)

Rcs - num of single commands per hr

Rcd - num of dual commands per hrRc - total cycle rate in cycles/hr

Rt - num transactions per/hr


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ME 486 - Automation

AS/RS material handling analysis

Equations:

AS/RS dimensions W = 3 (x + a) a = 6 inL = ny (y + b) b = 8 in

H = nz (z + c) c = 10 in

capacity per aisle C = 2 ny nz

single command cycle Tcs = Max {L/vy , H/vz } + 2 Tpd uniform racks,random storage

dual command cycle Tcd = Max {1.5 L/vy , 1.5 H/vz } + 4 Tpd

utilization 60 U = Rcs Tcs + Rcd Tcd

hourly cycle rate Rc = Rcs + Rcd

num transactions per hr Rt = Rcs + 2 Rcd


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ME 486 - Automation

AS/RS example (from text)

Given a 4 aisle AS/RS layout, each aisle contains 60 horizontal racks and 12 vertical racks.

Unit load dimensions are x = 42 in, y = 48 in, and z = 36 in. The S/R machine has a horizontal

speed of 200 ft/min and vertical speed of 75 ft/min. It takes 20 s for a P&D operation. Find

a) Num of unit loads that can be stored

b) Total dimensions of AS/RS

c) Single and dual command cycle times

d) Throughput per aisle assuming utilization = 90% and num of single command

cycles equals the num of dual command cycles

Solution:

Total capacity = 4C = (4) 2 ny nz = (4)(2)(60) (12) = 5760 unit loadsWidth = 3 (42 + 6) = 144 in => 12 ft/aisle

Length = 60 (48 + 8) = 3360 in = 280 ft

Height = 12 (36 + 10) = 552 in = 46 ft


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ME 486 - Automation

AS/RS example (cont)

Solution:

Single command cycle time = Tcs = Max{280/200,46/75} + 2(20/60) = 2.066 min/cycle

Dual command cycle time = Tcd = Max{(1.5)(280/200), (1.5)(46/75)} + 4(20/60) = 3.432 min/cycle

Utilization = 0.9: 2.066 Rcs + 3.432 Rcd = 60 (0.9) = 54 min, but Rcs = Rcd

Thus, solve and get Rcs = Rcd = 9.822 command cycles/hr

System throughput is the total number of S/R transactions per hour = 4 Rt

Throughput = 4 Rt = 4(Rcs + 2 Rcd) = 4(29.46) = 117.84 transactions/hr


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ME 486 - Automation

AS/RS questions

1. Who are major vendors of AS/RS?

2. Describe their components (power source, transmission system,

communication system, etc.)?

3. What are typical costs?

4. What type of interfaces do they have? How are they programmed?

5. How fast do they move?

6. What are load capabilities?

7. Unusual maintenance requirements?

8. What type of S/R control is used? PID?

9. Who are primary users?


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ME 486 - Automation

Conveyors

Definition - A conveyor is a

mechanized device to movematerials in relatively large

quantities between specific

locations over a fixed path.


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ME 486 - Automation

Conveyors

Roller conveyors - Series of tube rollers perpendicular to motion direction, which can bepowered or use gravity for motion.

Skate-wheel conveyors - Similar to rollers but use skate wheels parallel to motion direction.

Belt conveyors - Drives move flat or belts shaped into a trough.

Skate

wheel

Belt


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ME 486 - Automation

Conveyors

Chain conveyors - Uses loops of chain

that are typically moved by sprockets asdriven by motors.

Overhead trolley conveyors - Items are

moved in discrete loads by hooks or

baskets suspended from overhead rails.

Trolley


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ME 486 - Automation

Conveyors

In-floor towline conveyors - Similar to

overhead trolley but carts are pulled by

hook to in-floor conveyor.

Cart on track conveyors - Items are

moved by a cart attached to a rail system,

which uses a rotating tube to move the

cart along the rail.

Towline


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ME 486 - Automation

Conveyor material handling

Terms:

vccarrier average speed

(c = conveyor, carrier, cart, etc.)

scmaterial spacing on conveyor

TLloading time (min)

TUunloading time (min)

Rfmaterial flow rate (parts/min)

Lddistance between load and unload

Ledistance of return loop (empty)

Llength of conveyor loop

Tddelivery time

npnumber of parts per carrier

ncnumber of carriers

RLloading rate (parts/min)

RUunloading rate (parts/min)

Tctotal cycle time (min)

Nptotal number of parts in system

Note: If one part per carrier, then part flow rate

is carrier flow rate.


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ME 486 - Automation

Conveyor handling analysis

Equations

single direction:

time from load to unload Td = Ld/vc (min)

delivery time = delivery distance divided by carrier speed

material flow rate (np = 1) Rf= RL = vc/sc1/ TL (num carriers/min)

system flow rate = loading rate = flow rate of carriers on conveyor

material flow rate (np > 1) Rf= np vc/sc1/ TL (num parts per min)

system flow rate = loading rate of parts = flow rate of parts on conveyor

unloading constraint TU TL (min)

unloading time must be less than loading time or else pile up carriers


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ME 486 - Automation


Equations

continuous loop:

time to complete loop Tc = L/vc (min)

full loop carrier time = loop distance divided by carrier speed

time in delivery Td = Ld/vc (min)

delivery time = delivery distance divided by carrier speed

number of carriers nc = L/sc

num of carriers = loop distance divided by carrier spacing

total parts in system Np = np nc Ld/ L

parts in system = num of parts per carrier times num carriers with parts

material flow rate Rf= np vc/sc (num carriers per min)

material flow rate = num parts per carrier times carrier flow rate


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ME 486 - Automation


Equationsrecirculating:

Speed ruleoperating conveyor speed must fall within a certain range

from load/unload rates Rf= np vc/scMax{RL , RU}

flow rate of parts on conveyor must exceed the max load or unload part rate to maintain part spacing

from time to load/unload carriers vc/scMin{1/TL,1/TU}

flow rate of carriers on conveyor must exceed the max load or unload carrier rate to maintain part spacing

Capacity constraintconveyor capability (np

vc/s

c) must exceed desired/specified

flow rate Rf

conveyor speed and carrier parts np vc/scRf

Uniformity principleloads should be distributed uniformly over the conveyor


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ME 486 - Automation

Conveyor questions

1. Who are major vendors of conveyors?

2. Describe their components (power source, transmission system, I/O

subsystem, etc.)?3. What are typical costs?

4. How are they programmed and controlled?

5. How fast do they move?

6. What are load capabilities?

7. Unusual maintenance requirements?

8. Who are primary users?


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MatHandling[1]

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