How Frequently Should You Purge Your Injection Molding Machine?
                     How Frequently Should You Purge 
Your Injection Molding Machine?
Regular maintenance is crucial in the injection molding industry, and one of the most 
essential tasks in any production schedule is purging. The Use of a 
Purging Compound for Injection Molding is not only about keeping your machines clean
—it’s also about maximizing efficiency, reducing downtime, and ensuring product quality.
But how often should you purge your injection molding machine? The answer depends on 
several factors, including material changes, production cycles, machine usage, and the type 
of resin being processed.
Purge During Material or Color Changes
One of the most common times to use a Purging Compound is during material or color 
transitions. Without Purging, remnants of the previous material or pigment can remain 
inside the screw and barrel, leading to contamination in the next run. This can cause 
inconsistent coloration, black specks, or even defective parts.
If you’re changing from a dark to a light color or switching between incompatible materials, 
always schedule a purge between transitions. This minimizes scrap and maintains product 
integrity.
Purge at the End of Each Production Run
Many manufacturers schedule a purge at the end of each production cycle. This practice 
helps clear out leftover resin before it cools & hardens inside the barrel. Cold resin buildup 
can lead to significant downtime during startup and may require manual cleaning.
By Purging at the end of a shift or job, you ensure the system is clean and ready for the next 
run—saving both time & labor.
Purge Before Machine Shutdowns
If your injection molding machine will be idle for an extended period, purging before 
shutdown is a smart move. Sitting resin can degrade and carbonize, making it difficult to 
remove once operations resume. This not only affects product quality but can also damage 
the equipment over time.
Using a High-quality Purging Compound 
for Injection Molding helps prevent thermal 
degradation and keeps internal surfaces in 
optimal condition.
Routine Preventive Maintenance Purging
Even if you’re not switching materials or 
shutting down the machine, regular preventive 
purging is recommended. Based on your 
production volume and the types of materials 
used, a purge every 100 to 300 hours of 
operation is a good starting point. This 
removes unseen residue and prevents long-
term contamination or wear inside the barrel.
Watch for Warning Signs
If you’re seeing signs like dark specs, inconsistent melt flow, or part discoloration, it may be 
time to purge—even if it’s earlier than your routine schedule. These are indicators that 
residue is building up inside the machine & affecting production quality.
Keep Your Machine Production-Ready
Routine Purging keeps your injection molding equipment running efficiently and your final 
products consistent. Whether you’re performing regular maintenance, switching materials, 
or preparing for downtime, having a trusted Purging Compound on hand makes all the 
difference.
Explore industry-tested solutions with Unicleanplus—trusted for performance & reliability 
in plastic processing.
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