How to avoid contamination and downtime caused by residue?

Reduce downtime and prevent contamination caused by residue with these 3 easy tips.
ASACLEAN purging compound granules

23 Feb 2023 |  2 minutes read | Share article:   

Preventing contamination and resin purging residue is critical for plastics processing companies as it can lead to unsellable products and costly production downtime. Using the right purging compound and purging process can reduce or eliminate contamination, scrap rates, and downtime. Here are three easy ways to prevent residue and contamination during resin transitions:

 

1. Choose the right purging compound grade for residue-free operations

Purging compound selection plays a significant role in avoiding contamination during production. Use the appropriate purging compound grade based on the melt index (MI) of your resins.

A low-residue purging compound is ideal for high-MI resins. If contamination exists, use a glass-filled purging compound (for screw and barrel only) grade before the low-residue grade.

 

2. Optimise your purging process with proper temperature control

Using the recommended temperature range for your purging compound and resin is crucial to ensuring a successful purging process.

To prevent residue from building up during the purging process, it's essential to use a purging compound that's designed to work at the recommended temperature range for your resin. Make sure to use a purging compound designed explicitly for your resin's temperature range, such as a low-temperature purging compound for PVC.

 

3. Improve purging efficiency with aggressive purge techniques

When changing production resins, residue issues can be minimised by taking assertive steps. Increase screw speed and back pressure to their highest safe levels to fully displace purging compound residue. These techniques are especially effective for resins like Bayer’s Texin, Desmopan (TPU), and Makrolon (PC). Minimise residue by taking these simple yet effective steps:

 

Injection moulding techniques

  • Increase backpressure to the maximum safe level and keep the screw in the full forward position.
  • Once the barrel is full of production resin, increase the screw speed to the highest safe level.
  • To ensure complete purging, perform short, high-velocity injection shots and drop the backpressure after eliminating purging compound residue.

Extrusion techniques

  • Close all barrel vents.
  • Maintain back pressure with a breaker plate.
  • Utilize the highest screw speed the extruder can handle without causing the motor to trip.

Say goodbye to contamination and downtime with effective purging solutions

Efficiently switch between colours on one machine by using the right purging procedures. Prevent residue issues, eliminate contamination, and increase machine capacity with the cleaning power of a proper purging compound and process. Experience a significant reduction in scrap rates with easy-to-follow purging procedures.

 

Request a free sample of ASACLEAN purging compound and see how it can prevent residue-related contamination and downtime.

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Fast facts

Residue buildup occurs when small amounts of previously melted plastic remain in the barrel or screw of an injection molding machine. This can lead to a range of problems, including discoloration, streaks or spots, and reduced product quality. In severe cases, it can also cause downtime as machines need to be cleaned and purged.

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