Tapped threads and threaded inserts in glass reinforced PEI (Ultem 2300)

[erik3000]

I am planning to build a part out of Ultem 2300, also called Duratron, which is a glass fiber filled polyetherimide. It will be made from 4" thick stock sheet.

I plan to use threaded inserts in this material, which require tapping. What I can't find is any literature or specifications which give any allowables on tapping/threading for this material. Have never worked with it before, so there are concerns about the threads holding up, cracking, etc.

Anyone know where I can find reliable data on this?

The other option is to bore holes and set the inserts in with epoxy or some kind of adhesive.

 

[1gibson]

Watch CTE if the inserts are metal, may cause cracking. I assume you have slightly elevated temps based on material choice?

 

[CoryPad]

Inserts applied with heat or ultrasonics would be another popular choice.

 

[erik3000]

The temps will not be high or vary much-- I chose the material for it's high mechanical strength and non-directional properties compared to other polymers or composites.

 

[rickfischer51]

What does Sabic say? They say this material is used for machined parts. Maybe they have a fabrication guide on their website.

Rick Fischer
Principal Engineer
Argonne National Laboratory

 

[erik3000]

I could fine no relevant information, however this document from GE Plastics (which I believe was acquired by Sabic), has one brief mention of it:

http://www.hycompinc.com/PDFs/ULTEMProductBrochure.pdf

Page 44, 7.3 Mechanical Assembly. Says that heat or ultrasonic install is preferred, but that "overmolding and external threaded inserts [what I'm intending to do] are also possible."

However no guidelines are given.

 

[rickfischer51]

Yeah, Sabic bought GE Plastics. Well, overmolding is out because you are machining from a slab. Not sure if the heat or ultrasonic method would work for glass reinforced. I'm not an expert here, but I seem to remember something about the glass fiber segregating and causing weak resin-poor zones at the insert. I did try to ultrasonicly stake a 30% glass filled nylon part. Didnt work well. Check with somebody like Branson or Dukane. Also, note the section on screws. Some threaded inserts are designed to thread into an unthreaded boss. They could be thread forming or thread-cutting. Per your link, thread-cutting should be used for glass reinforced grades.

Rick Fischer
Principal Engineer
Argonne National Laboratory