Plastic Products and Mold Design

What exactly would you like to know about it? Maybe I can help a little.

Hi Marcio,

That will be great.

Not much info is provided on net.

I would like to know how the MIM mould designs are different from any other injection mould designs, and what are the precautions to be taken while moulding?

Can any other Injection moulding shop take up MIM by changing the screws and barrels?

Thank you in advance,

Murali K

Well, I think that the design process is similar to the plastic moulds. The big difference is that you must use a much larger shrinkage factor. About 16 to 20% depending on the product.

An important aspect is to always put the injection gate near the thicker wall, to prevent failures on the inner parts.

You can find useful information about the machine here:

https://www.arburg.com/us/us/products-and-services/injection-molding/processes/powder-injection-molding/

https://www.arburg.com/fileadmin/redaktion/mediathek/prospekte/arburg_pim_522785_en_gb/

Mr. Marcio,

Info was very useful.

However Imagining 16 to 20% shrinkage !!!!!!!!!!!!!!!

What should be the mold temperature?

As per the mold theory outer surface cools first and then the inner section.

We face a lot of molding problems with just 1.5 to 1.7% shrinkage.

With such large shrinkage values can we achieve the required part accuracy?

Can we mold defect free parts?

What are the part design principles for MIM molded parts?

Well, this extra 20% in fact is going to be lost after the part is molded. It is an agent to keep the metal powder in place( called green part). After injection you have to put the part in a solution that will disperse this green part. Then you have to heat the part so it gather the physical properties desired. So, I think the best approach is to design the final part without any shrinkage, and then when you create the cavities you apply that extra 16 to 20%.

You can find even more information about design guidelines on this website:

http://mimaweb.org/About_MIM.htm

I hope it helps at least a little bit =)

the link shared by marcio is good(http://mimaweb.org/About_MIM.htm)

Great Knowledge shared Mr.Marcio.

Kindly keep continuing your discussions.

Every one is getting educated

Have a nice time.

Wish you all the very best.

Thank you! I hope you can find all the answers you need to keep your project going!