Injection molding wall thicknesses - tips?

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Hello,

I am a mechanical engineer currently in the design phase of developing rectangular housings using PA66 GF30 material. From my previous projects, I’ve encountered challenges with achieving consistent dimensions, particularly with thin wall sections. In my current design, a critical feature has a specified wall thickness of 0.7mm, which I suspect might lead to warping and strength issues based on past experience.

To preemptively address potential problems, I am considering adjusting the wall thickness. However, this could affect the overall width, initially designed at 80.0mm (+/-0.05mm).

  • What is the generally recommended minimum wall thickness for injection molding of PA66 GF30 to ensure structural integrity without compromising dimensional accuracy?
  • Given the stringent tolerances required, would it be appropriate to adhere to ISO 20457 for general tolerances in this situation, which is specifically tailored for injection molded plastic parts?

I would appreciate any insights or suggestions on how to best approach this design challenge.

Risolto daAnton Huryn

Hi everyone! I agree that 0.7 mm is not enough for casting,

because we have to keep in mind the draft angles, which are also necessary.

So if the bottom of the wall thickness is 0.7 mm, even with a height of 10 mm and an angle of 1 degree on each side (recommended), the top thickness will be only 0.35 mm.

As you can see in the picture, with a thickness of 1 mm you get a pretty good result at the top of the rib.

I hope this is helpful to you,
have a good day 🙂

    • R

      Hello,

      I am a mechanical engineer currently in the design phase of developing rectangular housings using PA66 GF30 material. From my previous projects, I’ve encountered challenges with achieving consistent dimensions, particularly with thin wall sections. In my current design, a critical feature has a specified wall thickness of 0.7mm, which I suspect might lead to warping and strength issues based on past experience.

      To preemptively address potential problems, I am considering adjusting the wall thickness. However, this could affect the overall width, initially designed at 80.0mm (+/-0.05mm).

      • What is the generally recommended minimum wall thickness for injection molding of PA66 GF30 to ensure structural integrity without compromising dimensional accuracy?
      • Given the stringent tolerances required, would it be appropriate to adhere to ISO 20457 for general tolerances in this situation, which is specifically tailored for injection molded plastic parts?

      I would appreciate any insights or suggestions on how to best approach this design challenge.

      0
    • M

      Hi Raul, 

      For injection molding with PA66 GF30, 0.7 mm is indeed a borderline, so whether it can work with such a thickness depends on the final design. As far as I know from my previous projects, a minimum wall thickness of about 1.0mm is generally recommended for Nylon to maintain structural integrity and dimensional stability. Given your specific tolerances and the need for precision, adhering to ISO 20457 seems appropriate to me as it offers guidelines tailored for injection molded plastics, helping to ensure consistency across your components. I would recommend checking with Xometry’s DFM team with your speicific drawings – they helped me optimize my design. 

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    • Echoing Michael’s post. 0.7 mm is relatively thin, so upping it slightly will help with flow and stability. Strength can be achieved through ribs, which should be about 60% of the outer wall thickness. Warp is something the Xomtery IM team can review as part of their DFM feedback, and there are techniques the team can use to mitigate risk to critical features within tooling design and molding operations. What’s best is that you provide your file for their review along with a technical drawing highlighting critical features for mates and function. 

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      Rispondi
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    • Xometry Engineer

      Hi everyone! I agree that 0.7 mm is not enough for casting,

      because we have to keep in mind the draft angles, which are also necessary.

      So if the bottom of the wall thickness is 0.7 mm, even with a height of 10 mm and an angle of 1 degree on each side (recommended), the top thickness will be only 0.35 mm.

      As you can see in the picture, with a thickness of 1 mm you get a pretty good result at the top of the rib.

      I hope this is helpful to you,
      have a good day 🙂

      1
      Rispondi
      1
      • R
        Anton Huryn

        Thank you!

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        Rispondi
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Injection molding wall thicknesses – tips?
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