High-grade engineering plastics (Delrin, in particular)

[Guardian452]

First-time forum user, ever, so Good Morning, Afternoon, or Evening to anyone reading this thread. My thanks to you, also, for taking time out to check it out.

I am currently assisting a colleague with a project which will involve the use of a high-grade plastic that would ultimately be molded to have pivots and seals. Looking around and talking to others gave me some names of engineering plastics like acetal (aka Delrin) and Polycarbonate. I just wanted to know if anyone worked with either of these two plastics, in particular - especially Delrin - and could say anything at all on their experiences in using them. Specifically, I'm interesed in their:

1)durability;
2)ability to take and hold onto color/ paint/ pigmentation;
3)general ease in molding, shaping and finish

If not with Delrin and/ or Polycarbonate, any advice or suggestions about *another* engineering plastic that someone's used and found satisfaction with would be immensely helpful and greatly appreciated. I apologize if I'm not getting terminology correct or adequately making my request clear; I have no engineering experience and just now trying to get a handle on all the lingo.

Again, my thanks for any and all advice.

 

[MikeHalloran]

Delrin, Nylon, and Polycarbonate are workhorse engineering plastics. These days they are not 'bleeding edge'. All are trade names that each refer to the root of a large family of resins, each with special virtues. Books have been written; find some and read.

To partially answer your questions,

1. Durability depends mostly on applied stress and environment. Environment includes presence/absence of UV light and certain chemicals. For PC, _any_ chemical can be problematic.

2. Painting structural plastics is not generally a good idea. White/natural Delrin can be colored with Rit fabric dye. All plastics can be compounded with pigments at some sacrifice in mechanical properties. Delrin is available precolored black, which greatly improves its UV resistance.

3. Delrin is very easy to mold and machine, PC much less so, but not difficult for a competent molder and a reasonably designed part.

There's a _lot_ more to it than that, and everything I've written above can be proven wrong, depending on what you are actually trying to do, which you haven't revealed, and probably don't know yet.

Contact molders and especially resin suppliers, who will bury you in technical literature if they smell even a hint of volume production.




Mike Halloran
NOT speaking for
DeAngelo Marine Exhaust Inc.
Ft. Lauderdale, FL, USA