Need good reference on material selection and design of plastic parts 2

[Tunalover]

Can anyone recommend a good, solid, practical reference book for the design of plastic parts, primarily injection molded

TIA for your recommendations.



Tunalover

 

[MikeHalloran]

One of my buddies used company money to buy a third-party plastics design handbook, comprising multiple paperbound volumes, stacking up to a foot thick. It was borderline useful, but it was out of date as soon as it was published, and it didn't have mechanical properties and such for specific resins. We didn't think it was really worth all the money it cost.

I found it better at the time to just call up the various resin suppliers and ask for design handbooks, which they published for each of the resins they produces. They would ship out as much as you asked for, or have a rep deliver it, free of charge.

Most of those resin suppliers have changed names or owners at least once since I dealt with them, but they're still producing tons of resin every day, and trying to get it into products that will take advantage of its best properties. So, I think, the thing to do is search for all the resins that might be useful for your product, go to the applicable websites, and download the individual per-resin design handbooks as pdfs.

You may have to register so that their reps can find you, but that's not necessarily a bad thing; a good rep can tell you stuff they don't put in the handbooks, and can look at your designs and prototypes and offer suggestions you'd never dream up on your own.

If you print out and bind the pdfs, when you get to a foot or more of thickness, you might have gained some idea of what you're trying to do.

Good luck and have fun.


Mike Halloran
Pembroke Pines, FL, USA

 

[btrueblood]

Mike's method has worked for me in the past. A lot of those reps have neat toys to give away too...

FWIW, the same method is a great way to learn electronics design, or at least enough to get the sparky's to wake up and pay attention to what they are saying in a meeting.

 

[IMF Plastic Mold]

In China, the best way is to work in a mold making factory.
If you want to be a designer or technican, you should try to work as a basic level worker! If you design a part, but cann't been molding. it is useless

Andy Du
Supply Plastic Molds&Molding
Zhejiang IMF Plastic Solutions Co.,Ltd

http://www.injectionmoldfactory.com/

 

[Helepolis]

I've just graduated a couple of month ago and straight away started working on designing plastic products, so basically I'm learning on the fly.
I've managed to collect a couple of design guides for plastics that might help you, they focus more on the design aspect of the product (wall thickness, ribs, holes, hinges etc.)

I can mail them to you if you wish, and if you're interested i can share with you my method of selecting (or at least try to ) the right polymer for the job, but bear in mined that i have access to FEM analysis software and Granta: CES selector (a software with a huge database of raw materials and their properties, processing and manufacturing data), but you can substitute the CES selector with this site.

 

[Tunalover]

Helepolis:

Thank you. Sounds like you have a wealth of information.

Tunalover

 

[Helepolis]

@tunalover
Well you give me to much credit, I'm quite new to plastic molded parts design myself (a bit more than a year, started as a student) and only next week the first batch of one of the products I've been working on will be ready at the factory and sent to me and the client for testing.

So my "method" might not be as reliable as i would like it to be, i'll know better when the product arrives .

Basically this is how i choose the right material, it's a short but repetitive process:
1) Build the CAD of the part implementing the thumb rules for plastic molded parts design.
2) Use the FEM software to determine the max stress that develops in the plastic part using a random material (as you know only force and geometry are needed, material properties effect deformation and yield points).
3) Determine the work conditions end requirements of the product in terms of thermal properties, electrical properties, mechanical properties etc. (there are a lot(!) of those parameters) this is where the material database software/site comes in. Those parameters will be you'r filter to narrow down to 3-4 desired polymers/elastomers. Try to add the most crucial properties first and adding others bit by bit, because if you include to much properties from the start you might be left with too few or none at all materials that can suite you'r needs. You'll probably be forced to compromise on some of the properties.
4) Using FEM software again, this time to test the materials you have narrowed down to using steps 2 and 3.
5) Don't settle on only one material, manufacture the prototype using at least 2-3 polymers. As i learned from forums on this site and googling, plastic part design is a trial and error process.
6) Test the plastic prototype parts.

I just want to clarify that i'm no expert so anyone is welcome to correct me.

 

[John2025]

If you're going to make them in-house, talk to your operators.
If you're having them made outside, talk to your suppliers.
Both of these groups will have their own opinions, some will be wrong, but most will be right. Of course in-house people will want ease of manufacture and suppliers will want to make money, but these are not always bad things.
Try not to fall in love with your own ideas and be willing to admit that your own idea sucks, lots of mine do.