4 Preventative Purging Tips to Super-Charge your Preventative Maintenance

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A lack of a preventative purging program may be costly in terms of plastics processing inefficiencies and production downtime. Preventative purging is focused almost solely on ensuring better part quality to give plastics processing equipment greater availability. When you focus on making your machines run better, precision and high output are naturally achieved.

The key is to not let your extruder or injection molding machine condition get so bad that a purging compound isn’t sufficient for a thorough cleaning. In these poor conditions, a manual screw pull may be necessary (which results in even more costly downtime). A preventative purging program helps to reduce production downtime going forward. Consult your Purging Expert for proper preventative purging procedures.

Here are four preventive purging procedures to help you reduce scrap rates:

1. Use an Adequate Amount of Asaclean®

Insufficient purging during downtime and changeovers is one of the most common causes of high scrap rates. When plastics processors don’t use enough purging compound, defect rates increase. Some companies tell machine operators to use a specific amount of purging agent, encouraging a one-size-fits-all approach.

However, the required amount of purging compound for each changeover varies by situation. For example, the more time that has passed since a screw pull and manual cleaning, the more contamination you’ll see in your system.

We will train operators to purge until cleaning is complete, within a certain tolerance range, prior to contacting a supervisor. Putting a machine back into production after using a preset amount of purging compound is not advisable.

Overuse is also a potential issue here. You don’t want your operators using more Asaclean® than is necessary, because waste is the enemy of profitability. Overuse isn’t in anyone’s best interest.

2. Seal Your Machines During Shutdown

To prevent contamination, it’s important to seal your machine with a thermally stable purging compound like Asaclean® U Grade during machine shutdowns and excessive downtime events such as PMs. Residual polymer degradation can delay machine startup and lead to excess material waste. Whether during a temporary or extended shutdown, sealing your machine is an essential step toward minimizing scrap rates.

3. Purge During Startups

At startup, extrude the sealing purge and follow up with one or two barrels of fresh purging compound before starting production. This aggressively removes contamination and carbon buildup that was pulled away from metal surfaces during sealing. Implementing this purge as part of your startup procedures helps reduce the time required to get up and running.

4. Purge Between Color & Material Changes

Whenever you change resins or materials, it’s critical that you purge your machines to remove previously run materials and protect against color contamination in your next batch. Although this is an additional step, the cost of including it in your purging procedures pales in comparison to the wasted materials caused by rejects.

Many plastics processing companies suffer from excessive material waste due to contamination during startup and changeovers. This is an unnecessary and avoidable cost. To avoid costly machine downtime and increased scrap rates, take a preventive approach to your purging procedures.

Ready to reduce your production downtime to protect your profits? Learn more about how purging compounds and process efficiency work in tandem.

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Topics: Injection Molding, Color Changes, Plastics Processing, Hot Runners, Purging Tips, Plastics Production, reduce downtime, black specs, material changes, Cleaning Injection Molding Machine, changeovers, faster changeovers, Reduce Scrap-rate, preventative purging, hot runner cleaning, Preventative Maintenance, Grade Selection

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