Stress relieve Delrin

[Lars Christensen]

Hi guy's,

I got some parts I got to mill, and they are deffently in the category were I need to stress relieve them, do anyone of you have any experience on this?, I did a search but did not find anything.

 

Thanks

Lars

[Mike Whitten CAD/CAM Contractors]

Lars,

 

I have done it a few times in the past but do not remember much about it. I would some searchs on the net. something like this: "acetal annealing delrin" or "acetal annealing" or "Delrin annealing"

 

I found lots of stuff on it. I would also check the manufacturers specs for the specific material you are running and check your local heat treaters.

 

HTH,

Mike

[jimspac]

I used to mill a lot of delrin parts but never needed to stress relieve. Careful machining techniques like balancing stock removal caused little or no movement.Stock came in large sheets and cut the workpieces out of them Once made flat parts stayed flat We used all black delrin, don't know it that makes a difference or not

[Bruce Caulley]

+1 to jimspac

 

If you maintain an equal an equal stock removal from each side you shouldn't have many problems. Balance what you are taking out against what sort of operation you are doing. ie. If one side has a deep pocket and the other is just flat then remove most of the stock thickness from the flat side.

 

If the sheet the stock is cut from is extruded and hasn't been planed you will probably need to pre-skim some material off 1 face before starting work on the other side.

 

Pressed sheet doesn't seem to be too bad, but you will need to keep an eye on it also.

 

As a rule if I was cutting parts from sheet I always had at least 5mm of excess on the thickness.

 

HTH

 

Bruce

[CAM-mando]

On close tolerance parts, I rough machine, let it stand 24 hours and finish machine.

 

I have never thermally stress relieved it, but ...

http://www.alhyde.com/pdfs/alh10695.pdf

 

CAM teh hurry up and wait

[Chris Rizzo]

Good topic, I've got about 20 mold cores to make out of Delrin next week.

 

Delrin seems overall pretty stable. There are all sorts of diff. grades, try and get the "virgin" white stuff. Seems to be more consistent than the black, and lesser grades of white, which I believe are not from virgin material.

 

As a general rule with all plastics I cut from each side, trying to "balance" stock removal.

Delrin cuts like a dream, though.

[Joels]

i machine delrin or acetal everyday and it is nice to machine althought it will break if the removal is too fast.

[jeff]

quote:

---

On close tolerance parts, I rough machine, let it stand 24 hours and finish machine.

---

+1!!!!

 

Same goes for UHMW also.

That sh!t will move all over the place.

Delrin does cut nice though.

[Fig sign]

Delrin is nice plastic to mill .

Good milling strategy and appropriate toos is a key .

I made very thin parts ,deep pockets ,thin walls and a lot of holes and without any unusual deflection

150 mm dia 300 mm height wall 1,5-2.5 mm

full of radial holes the part is so unrigid that you can brake it by hand still good

Or big sizes plates with pockets

Don`t stress it .

Clamp it gently ,use glue tape (mill without water ) or clamp it to the table ,use lathe footer and lathe the bottom on lathe (for round type parts ) or clamp with vises with a good amount of spare material ,do not clamp actual part .

Tools must be sharp

Balanced take -off of material and some other things will help you (like you can leave tabs (additional walls ) and gently mill or cut them afterwards conventionally or even with knife

This is a creative type of work and I love it

[Fig sign]

Also +1 for roughing and take off for a day or two

[Jim at Gentex]

I cut quite a bit of Delrin too and have never found the need to thermally stress relieve it either. The advice here is all good...especially about balancing the material removal as best as you can. This seems to keep your dimensions stable better than anything else I know of.

 

From my experience, the 550 and 507 (black) grade of Delrin is probably the best choice for close tolerance work and overall machinability.

 

The 100 (black) and 150 grades are mechanically tougher and hold up well where impact toughness is needed.

 

BTW the 100 and 507 black Delrin both become UV stable when the coloring is added, but other than that the mechanical properties between the 100 and 150, and between the 507 and 550 are essentially the same.

 

Lastly, if you need maximum toughness, the 570 grade is 15-20% glass filled and holds up well under harsher wear and tear conditions where other grades may fail. Consequently though, it is also tougher to machine, so the decision to use it should be made with this in mind.

 

HTH!

[Lars Christensen]

Mike,

Annealing worked much better as a search word, Thanks.

 

Thanks for all the advice guys, I have now layed it out so I do not need to put the acutely part in the vise, and I will machine it equal from all sides. I am going to run one part throw all operations, before I start the acutely 20 pcs. Quantities, so in that way I can see if annealing will be necessary.

 

Thank you so much all of you, you willingness to share knowledge is highly appreciated.

 

Lars

[DavidB]

I have to machine some Delrin so I did a search and found this post.

Lars,

How did you go?

With this material did you use Carbide or HSS cutters?

Coolant?

Thanks

[DavidB]

I have to machine some Delrin so I did a search and found this post.

Lars,

How did you go?

With this material did you use Carbide or HSS cutters?

Coolant?

Thanks

[Rekd™]

Load path, load path, load path. This is relevant in metal as well. I get good results in keeping stock removal centered, and by making sure, when possible, that my load paths are not going to influence the part.

[dougm]

lars

here is a link to our site

http://www.boedeker.com/anneal.htm

use caution when annealing plastics

a part that is 2x2x2 can grow or srink

over .100 after annealing

all the machining advice here is very good

[Roger Peterson]

Delrin isn't too bad if it is possible to follow all the advice above. If you are removing a large amount of material do just as said above, remove it equally from all areas. If you have pretty tight tolerances another thing that can help is if you need to end up with a part that is 2x2x2, start with stock that is 4x4x4 and face down all the sides 1/4" at a time all the way around, the center of the block has a lot less internal stress.

 

 

HTH

[MACHINEMASTERG]

we also cut alot of delrin since it comes in over size to nomonal sizes in the sheets we cut them to like 2 foot sqaure and then have them double disc ground to size like .500 .75 1.00 etc when we make parts from the stock it stays good ...hth

[Lars Christensen]

dougm,

Nice website, thanks that is going to be used