Acetal is injection molded all the time. How many parts are anticipated? Is the design consistant with injection molding?
If the part is small, the moldmaker may be able to use a MUDD base to cut your tooling costs. One problem with acetal is that it shrinks differently along the flow in the mold than it does across the flow. careful design can minimise the evil effects.
One of the things I do is review designs for molding to minimise moldmaking and molding problems. Let me know if you could use this service.
INSIDEMAN: I have very limited knowledge of molded parts. I do not think my part is appropriate for injection molding, however, I'm open to changing the material to accomodate the molding process, if cost effective.
I would like to take you up on your offer of assistance. How can I e-mail you directly a PDF file of my drawings?
If Insideman can't help.
But I am fairly sure he can.
He is very knowledgable about plastic parts.
I can help you to mold the parts cost effectively.
The downside with Acetal is that thick sections will usually have sink marks. The first rule to remember when considering injection molding. Always try to design your part with a nominal wall thickness. Typical working range (wall thickness) for Acetal is .030 to .120.
I mold quite a bit of Acetal and would be pleased to review your project. I have short run to high production capacity and work in high tolerances if needed (as in Medical).
The one question I would ask is are you looking at Delrin because it fits the characteristics you need in the final part, or because it was available in blocks that are easy to machine into prototypes. I have used Delrin to build prototypes to show the design concept, but then changed to a resin that was better suited for the production part. If the material characteristics of Delrin are not needed, you could save money using a commodity grade resin. But, as the others have said, it is an easy resin to mold as long as the design is suitable for injection molding.
Delrin can be molded easily. However, be sure the molder has capacity to run a heated mold (250 F). 100P is great for thicker wall parts but 500P which is a lower melt index, works better for thinner walls and I have had better luck in maintaining tight tolerances with it.
