Post treatment of Nylon 6 parts and also tips for processing TPE

[Crabstix]

Greetings from Sunny South Africa, Yes we do mold down here and yes the lions do wander through the factory from time to time.

Its my first post so go easy. I hope I have supplied enough info.

The part, not yet in production but I do have samples is a military search light, run in a Nylon 6 G.F 30%. It will go into production shortly but I am concerned about part stability later on, obviously it will be out in some extreme weather rain,sun and cold etc. Is there any benefit in doing some post treatment to the parts? and if so, How do I go about it? I have been doing some reading but its a bit vague. do I drop the parts into cold water or boiling water for X amount of time?

Then, I have a strap made from TPE: Processing data from material manufacturer is very broad: example: Processing temps 200 °C - 250°C
I know there are no hard and fast rules to molding but I would like some tips for molding TPE based on your experiences? I was told that it likes fast inject speeds and low inject pressures?

Many Thanks,
Nicholas

[Paolo]

Hello Crabstix,

I think you're talking about annealing process. You should talk with your supplier to recommend you about the best temperatures and times. If you're concerned about part stability I think you should focus on get a good process. What I mean here is do a process that will give you parts with low residual stress. Of course part design will affect it too. Make sure you dry the resin properly, as far as I know, too much dry or too little will bring you brittle parts.

For the TPE, I never processed but I heard that it likes high injection speeds, no pack pressure and little cushion. Be sure you have proper campling force and don't overpack the part. Once again, I heard it but I might be wrong. If you will not use pack pressure make sure you put some delay recovery time. Relatively to melt temp. I think you should go for middle range temp. or lower as you will go for high injection speeds the shear heat will be higher.

Wait for another opinion like Rick or Suhas, they will guide you on the right way.
Best of luck!
Paolo

[rickbatey]

For the PA resin we used to pour about 4 ounces of clean water into a bag inserted into the box of parts. Then we waited about a week before shipping tge parts. If not the air cylinder would crack the parts. The parts were small fans molded to cool the motor on a hedge trimmer. You can play with amount of water and time to find minimum amount of time required.
Soft resins do prefer fast fill rates, low hold psi and time, and warm molds. What brand are you using? Some are very easy to run and lot to lot run the same. Then there are the others that are a pain in the lower section of your body!
BTW on PA I always start on the low end of their resin spec sheet. That's because I can heat a resin quicker that I'll ever be able to cool it. Then watch screw motor run psi and examine the melt puddle to know if the resin is too hot or cold.
Thanks for the confidence Paolo!! Hope you're enjoying your bike!
Rick

[Crabstix]

Thank you for the replies. I am due to start up the TPE this morning....Holding thumbs that my lower section feels no pain today! The brand is from TEKNOR APEX?

On the PA, So the water is like a little sachet of desiccant beads that keep moisture away but instead we are adding moisture?


Cheers,
Nicholas

[iautry1973]

I used to work for a company that made gun holsters out of nylon. We never tossed water in with them or dunked them. They survived use with the military in Iraq/Afghanistan.

[rickbatey]

Moisture to PA is a plasticizer that greatly improves impact. You just can't process it wet.
By the time you molded the holsters and they got to the customer they had already regained their moisture content. Look it up if you're in doubt.
Rick

[iautry1973]

Rick, don't doubt you. I was just saying that the holsters held up to some pretty rough treatment without being rehydrated prior to getting to the customer.