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1 min read

Plastic Fabrication Review: Machining vs. Injection Molding

When it comes to plastic fabrication, there is not one simple, one-size-fits-all solution to creating your ideal custom part. Plastics machining offers many advantages (as we covered in our new technical paper), yet injection molding also has offers unique benefits.

So how do you decide between these two plastic fabrication techniques? Ultimately, your decision should come down to answering a few basic questions that will help you make the most of your material investment. Consider the following:

Plastic Fabrication Considerations:

  • What is the production quantity? 
    With injection molding, tooling can be expensive, so you need to be certain that the expensive tooling justifies the cost of the machined part. As a rule of thumb, we recommend injection molding for quantities over 5,000 pieces, and machining for anything under..
  • Are tolerances matched to the material? 
    Some materials cannot hold tolerances, which can impact their compatibility with injection molding. Read all about material selection and plastic machining in our new white paper: Machining Plastics: The Essential Guide to Materials, Tools & Techniques. 
  • How complex is the geometry? 
    If the part geometry very complex, you have many more fabrication options with machining vs. molding.
  • What is the stress on the material? 
    You need to determine if there are fillers in the resin you are using, since this will directly impact stress. 
  • What are the surface finish requirements? 
    This is particularly important in medical applications, where a proper finish is critical to the surface ID of the part. 

For a quick video review of this topic, check out the video (below). Of course, our Plastic Bearing Engineering Experts are always available to answer your questions too!