Aluminum / aluminium tooling question?

[debun]

We hired a consultant to help with mold design and I have some serious doubts with his stated abilities. The first 2 molds he designed failed and we are now on our 3rd attempt. Here are my questions.

1) Is it common to put the gate geometry in aluminum? (point gate ~0.030” opening via DMAX hot bushing). The few people I spoke to said they always used a steel insert. We have experienced gate freeze and the gate completely blowing out on our first 2 tools, yet our 3rd attempt we are going to do the same because he’s a “expert”.

2) The Zytel 101L design guide states the injection pressure will be between 5,000 and 20,000 psi. Is this pressure the gate geometry will actually see i.e. plastic flowing through it, or once the cavity is filled the packing pressure will be between this range?

3) Is there an idiots guide to mold design? I’ve never designed a tool in my life but I’m thinking I may need to take control pretty soon.

[brentb]

Maybe your "xpert" read or wrote that book.

Hanser (who also publishes Suhas"excellent book) has some books on the subject of mold design and construction.

KOM

brent

[rickbatey]

DuPont has tons of molding designs on their website for free. You just have to sign up for free and download what you need. They made me a hero with their info for molding paramaters and tooling requirements for POM.
Is the nylon filled? Either way I'd insert the gate area. I've worked in shops that always insert the gates for ease of repairs. BTW-Is he having the ejector pins running in a steel sleeves to protect the softer mold base from early wear?
Rick.

[debun]

The nylon is unfilled and no sleeves on the ejectors . I checked the Dupont website and they only seem to have resin specific documents. Did you find mold design specific documents?


DuPont has tons of molding designs on their website for free. You just have to sign up for free and download what you need. They made me a hero with their info for molding paramaters and tooling requirements for POM.
Is the nylon filled? Either way I'd insert the gate area. I've worked in shops that always insert the gates for ease of repairs. BTW-Is he having the ejector pins running in a steel sleeves to protect the softer mold base from early wear?
Rick.

[rickbatey]

Look for their design assistance and best practices information. It had examples of say a round handle with spokes inside and first showed the design in steel and then showed how the part from plastic should be designed. It had info concerning where to place holes and even water line placement in the tool. They also showed gate sizing formulas and showed best practices concerning runner and sprue bushings.
Rick.

[Paolo]

Hello @debun , pm if you want some docs. about mould design that I found on the internet.

[iautry1973]

Protolabs has a mold design for dummies book.