How to reduce deflection?

[Sanjay_paul]

Hello everyone,
I have a part which is getting 7.9mm deflection.Is it possible to see how the deflection is reduced by adding cooling channel and rerunning the analysis. If yes, what are the steps after adding cooling channel to get better deflection result. I have previously run a simulation with and without cooling channel but there is no difference between the deflection results. Maybe I am doing it wrong way. Please comment your valuable opinion if you have faced the same problem.

Comparison with and without cooling channel

Regards

Sanjay Paul

[madhukeshwart]

1. If cooling is uniform at both core and cavity side. Then deflection may not  improve much for such parts, with cooling vs without cooling 

2. Try to increasing coolant temperature  at core side, which may increase core side temperature and shrinkage.

Then deflection may improve in z-direction. but it may not be drastic change in deflection . Try and confirm

3. For such long and flat parts,higher deflection  may not be a issue during assembly, as snaps will be at end fill region, which helps to assembly properly.

confirm with actual part

[Sanjay_paul]

Hello Mr. Madhukeshwart,

Thanks a lot for your opinion.I will rerun the simulation as per your advise and let you know what will happen. What should be the temperature of cooling channel and how much should I reduce in core side in your experience? what should you recommend? I was using 25degree Celsius in previous simulation.

Regards

Sanjay Paul

[madhukeshwart]

Try to increase with 5 DegC & 10 Deg C

run iterations with different options 

[Anonymous]

Hi @Sanjay_paul

I would like to ask few questions regarding the flow or cavity balancing & pressure distribution, before giving suggestions on warpage reduction.

please do share the fill time plot along with Pressure @ V/P switch over plot also the packing profile you used with the gate freezing time.

Thanks

[Sanjay_paul]

Hello Sabarinathan,

Thanks for your comment. I have added the images as you requested.

Regards

Sanjay Paul

[Anonymous]

Hi @Sanjay_paul

You have to make sure that we have achieved flow balancing on each part. adjust the feed system position until you get the flow balanced condition.

Option01 - End fill should be on all these 3 regions & check the results (Refer attached images). definitely your injection pressure will get reduced once the flow has been balanced in the part.

Option02 - Try achieve the flow balancing condition on this four end fill regions.

Optimizing the flow is a primary step to follow which will solve most of the filling related issues.

This might also sometimes help reducing the warpage & the pressure requirement to fill this part.

Try & let us know

[Anonymous]

I dont know why Option02 picture was not uploaded.

im adding again Option02 picture - try get the end fill on this regions

[PascalGosset]

Hi Paul,

I don't really understand if you are talking about an existing part or not.

It'd be also useful to know what is the material injected.

Personally, I think warp predictions are +/- reliable in this order : material with glass fibers > amorphous > crystalline.

It seems you used a 3D mesh. For parts so long, I think a Dual Domain mesh is sufficient and much more faster.

Of cause, results can be very different (but... witch is the worst???  😞

Concerning the cooling, I believe it takes a lot of time for modeling and calculation and shows poor differences.

Then, what to do to reduce deflections?

That's a terrible question....   😞

It's rarely easy, and never logic. So try the modifications that can be done.

(I warn you: sometimes it is not enough).

My first reaction is to suppress the ribs. I just did it today. (I'm not sure my customer will appreciate 😉

But this often reduces (not suppress) the deformation (-70% today).

And like this, the part is less rigid and can be deformed for its assembly in the final device. 

Good luck.

[mppkumar]

Hi @Sanjay_paul

Procedure for optimizing warpage

1) identify the causes of warpage

     - shrinkage

     - fiber orientation

     - cooling

2) if the warpage is influenced by cooling, then you may need to optimize the cooling channels based on core and cavity side temperatures.

    if the effect of cooling is negligible, optimizing the cooling channel is not a solution to reduce the warpage

3) in your Comparison with and without cooling channel - image, noticed you have used dual domain mesh

in case of DD mesh mesh match should be more than 90% for better prediction of warpage.

[Sanjay_paul]

Hello Mr. Madhukeshwar,

As you said I had run my simulation with 5 DegC & 10 Deg C. Comparison with and without cooling is given below. Small change in deflection.

Regards

Paul

[Sanjay_paul]

Hello pascal,

Yes I am talking about a existing part and it has deflection but not large as simulation. Material is LG ABS HI-121H. I used Dual Domain mesh with cooling line but the comparison between with and without cooling is not making any sense.I think suppressing the ribs will cause to more deflection because ribs increases the strength of a product.

Regards

Paul

[Sanjay_paul]

Hello Pradeep Kumar,

Thanks for your opinion. My model has mesh Match percentage 87.1% and  Reciprocal percentage 86.7% . Can you tell me how can I get better result in deflection adding cooling channel?

Regards

Paul

[Sanjay_paul]

Hi Sabarinathan,

I am working on this fill balancing. I will get back to you when it is done.

Regards

Paul

[mppkumar]

Hi @Sanjay_paul

I hope you have used cooling circuit wizard to create the cooling channels.

you are trying to correlate the warpage of actual part with different cooling channels using Moldflow

If this is the existing part, try to simulate the exact cooling channels as in the tool 

if you are trying to correlate the results, first you should replicate the problem in Moldflow

1) use the feed system as in the tool

2) model cooling channels as in tool

3) use same material 

4) try to incorporate process parameters as used during production

[mppkumar]

Having ribs at times increases warpage, Please don't go by the impression having ribs will reduce warpage

CAE tools like Moldflow are there to evaluate different designs

please try different iterations with different rib structure and optimize your design

[mtrujil1]

are those deco caps for door Refrigerator???

In my last job normally we used 4 cold gates per cavity, our lessons learned were reduce all flow lengths to improve warp predictions; also please try increase Cavity or Core Temperature ~25C of difference between sides.

[Sanjay_paul]

Hi Pradeep Kumar,

Yes I used cooling circuit wizard to create cooling channel because firstly I just wanted to know that adding cooling channel reduces warpage.It was my main goal.I really agree with your opinion about the steps you said and also about the ribs .

Suppose your are getting deflection without cooling channel and adding cooling channel you get less deflection. Do you have experienced something like that?If yes can you please give me some snaps comparing with and without cooling and steps how do you do it?

Regards

Sanjay Paul

[Sanjay_paul]

Hi mtrujil1,

Yes you are right it is a door cap for our refrigerator. Thanks a lot for your opinion. About the temperature do you mean the difference between core and cavity temperature need to be 25deg celsius?

Regards

Sanjay paul

[Sanjay_paul]

Hello Sabarinathan,

You had  given more importance in balancing the flow in your comment. Now I understand why balancing is more important firstly. Thanks a lot for your advise..

At first stage when flow is not balanced:

Deflection:10.04mm

At second stage where flow is balanced:

Deflection:8.835mm

At third stage when flow is balance and ribs are changed

Deflection:6.768mm

Regards

Sanjay Paul