Plastic Annealing

The importance of annealing plastic rod and sheet

  • Proper annealing of your plastic rod or sheet is directly related to the quality of the finished machined plastic part.
  • Rod and sheet present with different stress characteristics due to their unique geometric shapes.
  • For example, plastic rod reacts in a radial fashion since turned diameters are most affected by stress.  Flatness and curling are the most common problems caused by stress in sheet material.
  • Both of these issues are due to the improper cooling of the material after it is extruded at high temperature coupled with an inconsistent/bulk annealing process by the manufacturer.

Our plastic annealing process

  • We analyze each component and its material to determine the best in house plastic annealing and machining process.
  • We then determine whether annealing of material should take place before or after machining or in conjunction with another finishing process.  Add into this the specific annealing cycle and the type of racking system used and the combinations quickly become numerous.
  • Our expertise allows us to design a specific plastic annealing process tailored specifically to your component and your chosen material.
  • Contact us regarding our oven specifications.

Benefits of plastic annealing

  • The immediate benefits of annealing plastic are a blank or part that is stable and ready for finishing.
  • Long-term benefits include increased dimensional stability and the integrity of the part.
  • Shrinkage or expansion of the part is reduced as the plastic part ages because the internal stress is removed.
  • The integrity of the part can be compromised due to surface stress cracks that can develop if the material is susceptible to stress cracking and it has been polished or machined improperly.
  • Long drilled holes that have been burned will eventually radiate cracks if not properly annealed.
  • Polycarbonate and polysulfone are particularly sensitive to stress cracks.
  • Screw threads are a feature in a plastic component that benefits from annealing.  Part failure can occur since the screw places a steady long-term stress on the component in combination with the residual stress from the machining process.  Annealing the part reduces the machining stress at the threads and in most cases, the screw stress alone is not normally enough to cause part failure.