CAE moldex.docx

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CAEAutomotive Door Handle Manufacturer Uses

Moldex3D to Solve Weld Line Issues

Customer Profile

Customer: Hu-Shan Auto Parts Inc.

Industry:Automotive

Solution:Moldex3D eDesign

Country: Taiwan

Founded in 1972, Hu-Shan Auto Parts Inc. is a professional manufacturer specializing in door handles,window regulators (window lifters) and spare parts. Hu-Shan develops over 300 new items every year

and works with customers to build new tooling and develop new product lines. Focusing on the

aftermarket business, Hu-Shan strives to become the worlds leading provider of aftermarket sdoor

handles. (Source:Hu-Shan)

Executive Summary

Facing serious weld line problems, Hu-Shan sought ways to enhance the appearance of door handle parts

and hoped to achieve the following goals:

Identify weld line locations

Decrease weld lines through design changes

Assess the manufacturing feasibility of various design options
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Challenges

Theres an obvious weld line appearing at the end of filling. The mold manufacturer tried several times

but failed to avoid the occurrence of the weld line. Hu-Shan hoped to use Moldex3D molding simulation

software to verify designs and understand the cause of the defect.

Solutions

UsingMoldex3D eDesign Packageto generate true 3D meshes and changed the gate location and product

thickness to improve the product design. The optimized design successfully reduced the wall thickness

from 3.0mm to 2.0mm. Through adjusting the product thickness distribution and changing the cylinder

from solid to hollow, Hu-Shan successfully reduced the weld line length from 9.5 mm to 4.3 mm.

Values

The cost to modify a mold like this is around $1,600 $3,300 and $16,000- $33,000 for a set of molds. In

this case, Hu-Shan used Moldex3D simulation software to evaluate 46 design options without making any

actual tryouts, saving tremendous cost and time.

Case Study

In this case, Hu-Shan was trying to optimize the design of the interior door handle. The part was

manufactured in single gate configuration and had weld line problem. Due to the demand for durability

and aesthetics, the presence of weld-lines will reduce the mechanical strength and affect the surfaceappearance of the door handles. The presence of the weld line was found after the tool was built. In order

to reduce cost and effort in fixing or rebuilding the mold, its important to identify the cause of weld lines

and how to avoid it through Moldex3D simulation analysis. Through part adjustments, the weld line was

reduced within the part tolerance.
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The melt front time of the original design is shown in Fig. 3. And Fig. 4 shows the location of the weld

line and its filling time. The meeting angle and the length of the weld line therefore can be identified.

Fig. 5 The meeting angle and the length of the weld line of the original design

The flow front meeting angle is an important indicator of weld lines. According to the meeting angle of

the flow fronts, we can obtain the length of the weld line. Judging from the analysis result, when the

meeting angle reaches 90-135 above, the orientation of the plastic molecules becomes uniform with no

presence of weld lines. Therefore, by testing multiple designs of gates and wall thickness, the optimal

design and its design methods are shown below.


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Wall Thickness Design Change:

Increased the wall thickness around the center and decreased the thickness of the middle plane to

accelerate the flow front on the center. The design made the two fronts meet at the edge of the part,

creating larger meeting angle and shorter weld line length.

Oblique Fillet Design Change:

Using the oblique fillet design to create wall thickness variation to speed up the melt flow at the center

and slow down the melt flow on the periphery. This design made the two fronts meet each other with

larger meeting angle and shorter weld line length.

Boss Design Change:

Changing the boss design from solid to hollow near the location where the fronts meet to reduce the melt

volume filling in and avoid the flow hesitation happen on the left side.


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The optimized flow result is shown below:

Fig. 12 The meeting angle and the weld line length after design changes

Conclusions

Through Moldex3D CAE simulation results, Hu-Shan found that changing thickness distribution can

adjust the melt front advancement speed and further solve weld line problems.

In this project, Hu-Shan made changes on the structure, the thickness distribution and the gate location.

The meeting angle was improved by the changing the structure and the gate location to reduce the wall

thickness and the structure angle. The original weld line length was 9.5 mm. It has been decreased by

around 50% to 4.3 mm after making design changes.

Using Moldex3D simulation tool, Hu-Shan conducted 46 groups of designs to understand the cause of

weld lines and to further verify an effective design method to avoid weld lines taking place on the surface

of door handles.

Using Moldex3D CAE simulation, Hu-Shan was able to verify changes in wall thickness and gate

locations before actual manufacturing, avoiding costly tool tryouts. Based on the simulation result, Hu-

Shan was able to optimize the design and the weld line length, significantly improving the product

appearance and product strength affected by weld lines.

Source: Moldex3D


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CAEHow to Accurately Measure Product Dimension

through Warpage Analysis

Moldex3D Warp has been widely used to estimate the mold shrinkage rate by many tooling suppliers.

During the process of optimizing the processing conditions, the impact induced by product dimension or

product size specification should always be taken into account while making changes on the design. In

order to improve the part quality, users need to learn how to accurately measure product dimension to

optimize designs.

The most common method is to measure the distance between two specific points as the following steps.
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Step1:Open the project and select Total Displacementin Warpage Result

Step2:Click Measure

Step3:Double click on two desired mesh nodes to be measured
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The result of the distance, the linear shrinkage rate and the coordinates of the two chosen nodes can be

obtained before and after the deformation.

Sometimes, product dimension specifications are difficult to defined, for example, its defined by edge to

edge instead of point to point. For these cases, the deformed mesh can be exported and measured on the

CAD follow the following steps:

Step1:Click Set Warpage Scale

Step2:Click Export Deformed Model Option
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Step3:Set File Format,Warpage Scaleand click OKto export deformed surface mesh

After the file export is completed, the complex dimension specification can be defined and measured with

geometry functions or tools in CAD.

For some special cases, the measurement of dimension specification need to go through converting and

computing nodes , such as roundness measurement. In this case, the coordinates of measure nodes which

involved in post process can be exported by Measure Node Wizard in the following steps:

Step1:Choose Measure Node Wizard

Step2:Double click the desired nodes to add node ID to measure node list. If the number of nodes is too

large, the measure node attribute can also be set when generating mesh.
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Step3:Click Output CSVto export the node data for both the original and the deformed products.

From these data, the complex dimensions can be measured, which is useful for building better products.

Source: Moldex3D
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CAEEnhancing Product Quality via Conformal Cooling

Design

A look at two cases demonstrati ng the value of CAE softwar e at the pre-tooli ng stage3D printing and Rapid Prototyping (RP) are not new concepts in the manufacturing world. With more and

more price-friendly 3D printers available, self-manufacturing is not a dream anymore. However, for most

products, tooling is still irreplaceable. The concept of RP has been applied on conformal cooling

manufacturing for nearly two decades. Laser sintering is able to manufacture any arbitrary shape of

cooling channels which follow the contours of the surface; this can help reduce cycle time and create

higher quality parts.

Problems

Besides laser sintering, there are still other ways to makeconformal coolingchannels, such as vacuum

brazing and CNC machining. Among them, laser sintering can achieve the highest design flexibility.

However, it is also the most expensive one. There are also some disadvantages of the laser sintering

method. For example, the mold plate can deflect due to high energy from laser diode. The pipe surface

can be too rough, which makes water clog more easily. Others challengeslike sintering dimension and
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material limitationhave been greatly improved, making laser sintering more applicable to conformal

cooling manufacturing.

Product Defects

By changing the cooling design to make it closely follow the contours of a part, the temperaturedistribution will become more uniform and heat/cold spots can be eliminated. This can minimize heat-

induced product defects such as residual stress, warpage, void, sink mark, and etc.

Product defects are often highly related to its design. For example, if a product has ribs, it is highly

possible to sink at the opposite side of the ribs. If the cooling rate is too fast, voids can occur instead of

sink marks. Despite the complexity of product defects for various reasons, conformal cooling can still

help to minimize the overall warpageif properly designed. Here we will examine two common

defectssink marks and warpageand how conformal cooling can solve them.

Do I Need Conformal Cooling?

Most understand that conformal cooling offers many advantages. Owing to the high cost, conformal

cooling has not gained popularity among industries. One frequently asked question is: Do I really need

conformal cooling? It is always the ROI issue.

Generally speaking, two types of products are suitable for conformal cooling: products of cup/box-shaped

and of large curvature variation. Another important concern is product thickness. Since plastic is a poor

conductor of heat, if the part is too thick, the cycle time reduction may not be able to compensate for the

cost of sintered part.

Furthermore, how much warp can be improved if conformal cooling is applied? We should have the

answer before the mold is built, but how? An efficient way is using CAE software to simulate. The

following two cases can demonstrate the value of CAE and how it can contribute at the early pre-tooling

stage.

Sink Marks

The first case is a drill cover, and the average thickness of the part is 3 mm. The product contour is

perfect for using conformal cooling. At the red circled areas, sink marks will occur if the cooling time is

not sufficient (see Figure 1 and 2). For a baffle design, it takes 30 seconds to avoid sink marks at the core

side (see Figure 3). If the conformal cooling channel is applied, it only needs 20 seconds to prevent this

type of problem (see Figure 4).


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Figure 1 & 2 Red circled areas show the sink mark problem of the drill cover

Figure 3 Traditional baffle cooling channel design Figure 4 Conformal cooling channel design

Through simulation, the effect of conformal coolling can be easily identified. Figure 5shows the

comparison of temperature distribution between the baffle ( left) and conformal (right) design. The two

designs were set at the same temprature range. The core side temperature of the conformal design is much

lower than the baffle one since additional conformal channels were applied. The maximum sink mark

location (see Figure 6) from the simulation result exactly matched the real world molded part.


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Figure 5 The comparison of temperature distribution between the baffle (left) and conformal (right) desig

Figure 6 Moldex3D simulation analysis identifies the maximum sink mark location which correlates well

with the real-life molding result

Warpage

The second case is a digital camera cover (see Figure 7). This product will have a severe warpage

problem if baffles are only applied at the core side (see Figure 8). If additional conformal cooling

channels are applied (see Figure 9), the warpage can be improved significantly (see Figure 10).

Figure 7 Digital camera cover


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Figure 8 Baffle cooling design

Figure 9 Applying conformal cooling design

In this case, with conformal cooling channels, not only warpage can be improved, cooling time can also

be shortened by 30 percent (from 13 seconds to 9 seconds).


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Figure 10 Warpage has been significantly reduced

Summary

Conformal cooling has two major advantages in injection molding: (1) to improve cycle time and (2) to

enhance product quality. Laser sintering is the major manufacturing method for building conformal

cooling channels. To better estimate its ROI, the use of scientific tools is necessary. The two real cases

has demonstrated the positive effects of conformal cooling channels in reducing sink marks, warpage, and

cooling time and that CAE technology can effectively simulate these benefits.

Acknowledgements

Wed like to thankOPM Laboratory Co., Ltd. Japanfor sharing these cases and providing detailed

experimental data that made the validation study possible.

Source: Moldex3D
http://opmlabenglish.net/http://opmlabenglish.net/http://opmlabenglish.net/http://opmlabenglish.net/

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