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Contributor
nitinhadpe
Posts: 11
Registered: ‎03-20-2009

Regarding analysis in MPA

320 Views, 4 Replies
03-20-2009 12:45 AM
Dear all,

1. I want to analyse a multi cavity mold in MPA, then should I go for analysis with all cavities or single cavity analysis will be ok?
What will be the threats if i go for only one cavity analysis?
2. I want to analyse a family mold (box and cap type) then should I analyse it sepearatly or as a family mold?

Regards,
Nitin
Regards,
Nitin Hadpe
Neilsoft Ltd, Pune, India
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Contributor
MartinSchultz
Posts: 11
Registered: ‎03-23-2009

Re: Regarding analysis in MPA

03-23-2009 09:02 AM in reply to: nitinhadpe
My methodology has been to run an analysis of the part first, see if there are any problems, and then run the tool configuration. This will help you identify any problems you have with a part before committing to a more involved and longer multi cavity or family tool analysis.

Analysis of only one cavity will not provide you with the correct clamp force or peak pressure to fill that you would get with analysis of the entire tool. Of course you can't balance the runners of a family tool without running a tool analysis.
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Contributor
nitinhadpe
Posts: 11
Registered: ‎03-20-2009

Re: Regarding analysis in MPA

03-24-2009 12:44 AM in reply to: nitinhadpe
Thank you for your interest in answering this question.

Could you please elaborate your observations with respect to fill time , pressure at end of fill and flow front temperature results.
If these three results are important , what will you do ? Will you go for single cavity analysis, in case of multi cavity mould, and will follow the results religiously. Similliarly for a family mould what will be your methodology ?
Regards,
Nitin Hadpe
Neilsoft Ltd, Pune, India
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Active Member
ana_maria
Posts: 6
Registered: ‎03-16-2009

Re: Regarding analysis in MPA

03-26-2009 07:03 AM in reply to: nitinhadpe
Hi,

As Martin pointed out it is very important to analyze and optimize each part first then to analyze the complete mold in its final configuration. Depending on the geometries and number of cavities you are analyzing the results from the individual analysis to the family mold could be significant for which I strongly advice to run the complete configuration as time and resources permit.

Regards,
Ana Maria Marin

Moldflow Training Content Manager Edited by: ana_maria on Mar 26, 2009 2:08 PM
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Contributor
MartinSchultz
Posts: 11
Registered: ‎03-23-2009

Re: Regarding analysis in MPA

03-31-2009 07:48 AM in reply to: nitinhadpe
Fill time: I usually run a molding window analysis before a part analysis to determine an initial fill time to use in the analysis. (Read the on-line help to get the details) I usually use the recommended fill time, but stay with the mid range melt and mold temperatures for the material. Using the settings that will be used on the press will result in a more accurate analysis.

Pressure at the end of fill: For a part analysis I do not allow the pressure to fill the part to exceed 10,000 PSI. This allows about 5,000 PSI for pressure losses in the runner and on the press and still stays below our internal limit of 16,000 PSI. For a tool analysis I do not allow the pressure to exceed 13,000 PSI. I am currently collecting data to see if these guidelines are working for us.

Flow Front temperature: I used the guidelines from the help files to set a range limit of 18 degrees F. Any areas outside this range get a close examination to identify the cause. Sometimes there are issues with the stl file or mesh which can cause skewed results, sometimes there is a problem that can be fixed by increasing or decreasing the fill time.

I consider most of the results available to be important. I have a process where I check each result against a limit or range to identify possible problem areas. These limits were taken from the on-line help and adjusted based on experience. Make sure you have read all the help on each of the results and have a good understanding of the cause and effect. The Moldflow Design guide book by Jay Shoemaker is another resource to investigate.

I'm not sure I understand your last two questions, so here is some information on our methodology. We build lots of family tools with 2 to 36 parts and very few multi-cavity tools (multiples of the same part):
1) I typically run a part analysis when a design is complete or close to it. Design issues such as non uniform wall thickness and production issues such as the number of gates can be identified and resolved before we star the process of designing and building the tool.
2) I consult with our engineers about the proposed tool layout before we start the process of designing the tool.
3) Once a preliminary tool design is available, an analysis of the entire tool is run and the runners are balanced. If necessary, cavities can be moved or re-grouped at this time, since the tool is not built yet.
4) Once we have an analysis on the tool complete, the tool can be built using the specified cavity configuration and runner sizes.

Hope this helps.
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