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acetal same as delrin

nisse

Plastic
Joined
Jun 30, 2005
Location
Minnesota
I recently had a job that called out delrin as the material. The only material I could find that fit the bill was labeled acetal. I looked in the handbook and it had lots of info on acetal but I coundn't find anything on delrin. I have had plenty of jobs that called out one or the other and we ordered the appropriate material but not for this one. So I am wondering if delrin is a type of acetal, or a name brand or something completely different.
Thanks,
John
 
Yeah. I think so too. Or something like that. Except that Delrin is a trademark product name from DuPont, who are generally very adept at doing just that.

Check up on that info to make sure, but at least now you have some clues.
 
Delrin is also sold as Acetron. Acetal may have the same composition, I wouldn't know. I was working with some Acetal this week and it doesn't cut exactly like Delrin/Acetron. It is more britle. Might just depend on the manufacturer.
 
Here's what I learned about it.

Acetal is a term covering both homopolymers and copolymers. Delrin, strictly speaking, is DuPont's trade name for their homopolymer acetal. I believe the trade name for copolymer is Celcon. Delrin has become a general term used to describe all acetals much as "Kleenex" is used to describe tissues.

The homopolymer acetals are somewhat stiffer, stronger and harder than the copolymers. The downside is a small region of porosity near the center which copolymers don't have.

I learned this obscure information because a customer specifically requested that his parts be made of Delrin 150 because he needed that specific rate of thermal expansion.
 
Mike K,
Good info. Folks think Delrin is all the same and that includes the guys that spec it on drawings. Usually makes no difference but the stuff does behave differently. Delrin 150,180 500, 507 filled, not filled and the 57 other flavors of the stuff, both generic and DuPont. Glad you pointed that out, makes us all a bit wiser.
Good plastic suppliers know what can be switched and when you need to get the brand name.
 
one thing's for sure.... delrin/acetron ain't
cheap. it's become one of the more expensive engineering
plastics + most spec'd....because it works in place of most others, and works great where it is needed. delrin= less plastics failure, =less
f.u's, = engineer's dream.
 
I machine a ton of Ultem, and even though its 4-5 times as expensive as Delrin, I'd take it over Delrin to machine anytime. Though it's a rigid plastic, its pretty forgiving on chipping and cracking and very dimensionally stable, unlike Delrin in real moist applications. Now if I can just get the scientists to stop requesting PEEK :mad:
 
PEEK machines nice enough, but it's about 5X the cost of Ultem, which in turn makes it about 10X the cost of Delrin. PEEK burns easy in drilling operations, forget reaming or tapping it without some distortion and can generate burned marks on it if turned too fast. The likewise can also be said of Ultem. Otherwise it's a it nice product.

PEEK just seems to have this reputation in the academic fields as this miracle plastic. Unless you need a great insulator for an astronomical voltage or a material that's really chemically inert, Ultem is mechanically 75% of what PEEK is, at a fifth of its cost.
 
My list of preferred plastics: (in order of favorite to #%#^^&@%)
1 acetal co-polymer (great for everything, except chlorine apps.)
2 hdpe (better to machine than uhmw, but cheaper than pvc)
3 pvc (great for almost anything not requiring tons pf strength, or lubricity)
4 peek (not too bad to machine, but don't screw up! the cost :eek: )
5 plexiglass (chips easily though)
6 uhmw (easy to cut with sharp tools, a HUGE pain to debur :mad:
7 ultem (I have not had really good luck on the few parts I have made from it)
8-1K everything else that I don't like to machine

:D

Doug.
 
My list of preferred plastics: (in order of favorite to #%#^^&@%)
1 acetal co-polymer (great for everything, except chlorine apps.)
2 hdpe (better to machine than uhmw, but cheaper than pvc)
3 pvc (great for almost anything not requiring tons pf strength, or lubricity)
4 peek (not too bad to machine, but don't screw up! the cost :eek: )
5 plexiglass (chips easily though)
6 uhmw (easy to cut with sharp tools, a HUGE pain to debur :mad:
7 ultem (I have not had really good luck on the few parts I have made from it)
8-1K everything else that I don't like to machine

:D

Doug.
You probably mean acrylic ? What about polycarbonate ?
 

The following was copied and pasted from "Emco Industrial Plastics, LLC." in New Jersey.​


ACETAL VS. DELRIN: IS THERE A DIFFERENCE?​

Delrin is a type of acetal homopolymer and therefore generally interchangeable with others of the same class. This means that Delrin still offers the same core benefits of general acetal plastics, such as:

  • Excellent dimensional stability
  • Friction, fatigue, and abrasion resistance
  • Low moisture absorbance, leading to strong performance in wet conditions
  • Desirable electrical properties
  • Machinability to tight tolerances
  • FDA & USDA compliance
The main distinctions between Delrin and other acetal plastics stem from its composition as a homopolymer—it has a uniform crystalline structure rather than one incorporating multiple subunits. This leads to better properties in select areas—such as higher stiffness, flex fatigue resistance, and creep resistance—when compared to copolymers. Overall, Delrin offers slight but measurable benefits in terms of mechanical strength.

One negative characteristic specific to Delrin over other acetal plastics is its increased centerline porosity—an inconsistency in the center of the plastic caused by gas escape in the cooling process. While not a concern when the center of a rod is to be drilled out, this property can be problematic in certain food and medical related applications as centerline porosity increases the risk of bacterial growth.

Here’s the main takeaway: While Delrin does have some distinguishing properties, acetal plastics share enough in common that they are often interchangeable based on budget and other project-specific characteristics.
 








 
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