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Hello Marcin, Regarding the aspect, I would not recommend Bead blasting on this plastic material, because it will give a dull/grayer finish, which will be very noticeable if the material is black. The "as machined" aspect is generally appreciated for this material, and it can be specified on drawing to avoid machining marks, which leads to using a finishing milling step to keep the milling traces as small and discrete as possible. In my experience as support engineer, I can affirm that a lot of customers order parts in this material as an end part, without additional treatment or finish, but if the aspect is very important, you can specify a lower roughness, like Ra 1.6um, and indicate which surfaces should be ideally without tool marks. Best regards, Pierre-Yves

[Marcin99]

Hello!

I’m planning to use CNC machining for plastic parts (Delrin/POM) for the first time and have typically worked with metals before. I’m considering the ‘as machined’ finish with a standard 3.2 µm surface roughness.

For those who have experience with plastic CNC machining, can ‘as machined’ parts generally be used as end parts, or do they often carry too many machining marks? Would it be better to choose a bead-blasted finish (or another type) to enhance the appearance? These early prototypes might be shown to our end customers, so they need to look reasonably good. Any tips or experiences would be very helpful.

Also, could anyone share some pictures of polymer parts you have produced using CNC machining? I’d appreciate it!

Thanks, Marcin

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[Pierre-Yves Huet]

Hello Marcin,
Regarding the aspect, I would not recommend Bead blasting on this plastic material, because it will give a dull/grayer finish, which will be very noticeable if the material is black.

The “as machined” aspect is generally appreciated for this material, and it can be specified on drawing to avoid machining marks, which leads to using a finishing milling step to keep the milling traces as small and discrete as possible.

In my experience as support engineer, I can affirm that a lot of customers order parts in this material as an end part, without additional treatment or finish, but if the aspect is very important, you can specify a lower roughness, like Ra 1.6um, and indicate which surfaces should be ideally without tool marks.
Best regards,
Pierre-Yves

• This reply was modified 1 year, 7 months ago by
  P
  Pierre-Yves Huet.
• This reply was modified 1 year, 6 months ago by Uliana Krayneva.

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[Marcin99]

Thank you!

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[AM_EngR]

What Mr Huet replied is accurate – I have similar experience. Here’s also a picture I just made of one of my recent ABS CNC machined parts, you can see that there are traces of milling, but they are not too visible. 

• This reply was modified 1 year, 7 months ago by
  A
  AM_EngR.

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[Marcin99]

Thank you for sharing, that looks good, indeed. Nice texture 🙂 

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