Injection Molded PET Parts

Cryogenic Deflashing PET Molded Parts


PET Plastic Material & Uses

PET (polyethylene terephthalate) is a type of plastic that is commonly used to manufacture a wide variety of parts including bottles and containers for liquid & food products, packaging materials, and automotive components. Some specific examples include:

  • Beverage bottles: PET is the most common material used for bottled water, soft drinks, sports drinks, and other beverages due to its clarity, strength, and ability to maintain the quality of the contents.
  • Food containers: Many types of food, such as peanut butter, jelly, and salad dressing, are sold in PET containers.
  • Packaging materials: PET is used to make packaging materials such as blister packs, clamshells, and trays for small electronic devices and other consumer goods.
  • Automotive parts: PET is used to mold parts such as headlamps, interior trim, among other parts.

Injection Molding PET

PET plastic parts are fabricated through the injection molding process. Below is the typical process in which PET parts are injection molded.

  1. Pelletizing: The raw PET resin is first processed into small pellets, which are then fed into the injection molding machine.
  2. Heating: The pellets are heated until they become a molten liquid, which is then injected into the mold.
  3. Injection: The molten PET is injected into the mold under high pressure, filling all the cavities in the mold.
  4. Cooling: The mold is cooled to allow the PET to solidify and take on the shape of the mold. This step is called solidification.
  5. Ejection: Once the part is solidified, the mold is opened, and the part is ejected.
  6. Finishing: The part may go through some post-processing such as trimming, cleaning and packing.

Injection molding is a highly efficient and cost-effective method for producing large quantities of identical parts with tight tolerances. It can be used to produce a wide range of parts, from small precision components to large, complex shapes.

It is important to note that the process of injection molding PET requires precise temperature and pressure control, as well as a high-quality mold to ensure that the final product meets the desired specifications.

PET Mold Flashing Issues

PET parts can develop a flashing condition during the injection molding process. Flashing is the excess material that extends off of the part along the component’s edges, parting line(s) and gate vestige. This thin layer of residual material is unwanted and must be removed in order for the parts to be within tolerance. Mold flashing typically happens for several reasons:

  • Improper mold design: If the mold is not designed properly, it can create gaps or spaces where molten plastic can escape and create flashing.
  • Incorrect clamping pressure: If the clamping pressure is not set correctly, it can cause the mold to open slightly, allowing plastic to escape and create flashing.
  • Incorrect injection pressure: If the injection pressure is too high, it can cause the plastic to flow out of the mold and create flashing.
  • Incorrect temperature: If the temperature is not set correctly, it can cause the plastic to cool too quickly or too slowly, creating flashing.

Flashing can be removed by hand trimming, grinding or a variety of different deflashing processes.  It is preferable to avoid flashing in the first place. This can be done by developing a suitable process while taking into account the design of the mold, the material type and the actual injection molding process.

Flashing is not only a cosmetic issue, but it can also lead to functionality problems, especially on sealing surfaces. but also can create functional problems on the final part. If you are injection molding PET parts with mold flashing, it is worth exploring cryogenic deflashing.

The cryogenic deflashing process uses low temperatures, tumbling and media blasting mechanisms to remove residual mold flashing. Our process can even be completed on a same day service basis if needed. If you are interested in sending in PET plastic sample parts for a free evaluation, please contact us at or call us at 508.459.7447×105.