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Delrin - Does the color mean anything?

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  • #16
    Black Delrin does chip better, and hold size and such better.


    • #17
      Here's a list of the OEM approved grades of Delrin (only pages 4 - 10 are for Delrin). Looks like every major automotive manufacturer uses it.

      [This message has been edited by precisionworks (edited 03-07-2005).]
      Barry Milton


      • #18
        Finally got a reply on the blue DELRIN. It was a special order color from Dupont and is DELRIN, nothing else was added or changed. Same with the green.


        • #19
          ummmm, rit dye anyone?

          i've seen plenty of delrin dyed with RIT...


          • #20
            I've dyed lots of nylon with food coloring and vinegar but didn't know acetal could be. What's your recipe? Den


            • #21

              Most thermoplastics are easy to color during compounding. In some cases the color is strictly cosmetic, in other cases it may indicate a particular property. Uncolored acetal is sort of translucent white, you can't see through it, but light will transmit through. Most of what I've seen used for machining is colored white, light will not transmit through it unless extremely bright. Plastics that colored black are usually done so to provide a degree of protection against UV rays. (Black plastics can also be cheaper to make if recycling, you can color any junk black). Brown acetal is likely acetal combined with a little PTFE (Teflon) to improve wear resistance and decrease friction. Acetal copolymer is available in white or black, useful for applications that require meeting FDA or USDA requirements. This copolymer is available non-conductive like most plastics or conductive for applications where you might want to dissipate static. Acetal with glass fill is also available for improved resistance to temperature extremes.

              With regards to using acetal for applications that get wet, this is something that is pretty common, and acetal will probably absorb some moisture, but it is far superior to most grades of nylon, I would not recommend nylon for a outdoor or wet environment. In fact nylon absorbs moisture out of the air (I think the term is hydroscopic) and has to be dried before in can be injection molded. Keep in mind that vehicle manufacturers that purchase hundreds of thousands of plastic components specify the exact grade of plastic that is to be used. For a resin like acetal there are hundreds of different grades for different applications.

              Regarding the brittleness of black acetal, acetal is a thermoplastic, that means you can remelt it and form it or mold it into something else. Companies that do injection molding take defective molded parts, grind them up and feed them back into the molding process. This is commonly accepted practice and works okay as long as the percentage of recycle resin stays pretty low. Too much regrind and acetal tends to get brittle.

              Acetal is pretty easy to machine, sometimes I'll even use router bits, the sharper the better. However it will burn and when it does it stinks and burns your eyes, also the gas it gives off is toxic, so it's best not to burn it. (that is a pretty easy way to identify acetal though, take shaving and burn it, once you've smelled it you'll remember.)

              Hope this helps, (sorry I was so long winded)

              Take care

              [This message has been edited by bernie l (edited 03-08-2005).]


              • #22
                Lee Valley sells some small siZes of uhmw plastic, I can't remember for sure but I think they have small pieces of Delron also.


                • #23
                  <font face="Verdana, Arial" size="2">Originally posted by nheng:
                  I've dyed lots of nylon with food coloring and vinegar but didn't know acetal could be. What's your recipe? Den</font>
                  never done it myself, but it runs along the lines of boil a pot of RIT big enough to fit your parts and dump 'em in i think...

                  not much more help, but here's a pic:


                  they're delrin paintball bolts...

                  [This message has been edited by psomero (edited 03-08-2005).]


                  • #24

                    Thanks for the replies, thought the "absorbtion" was BS and it has now been confirmed.