A wire and cable extrusion facility in Kansas recently evaluated opportunities to optimize its purge process by reviewing the ideal operating temperature for a chemical purge compound used during periodic cleanouts. The primary objective was straightforward: reduce machine downtime associated with temperature changes while maintaining effective cleaning performance.
The facility currently processes XLPE at approximately 345°F and increases the machine temperature to 400°F for purge operations. However, raising the temperature from 345°F to 400°F requires a minimum of 1.5 hours, with a similar amount of time needed for cooling before production can resume. As a result, each purge event can consume several hours of valuable machine time.
From a performance standpoint, chemical purge compounds often benefit from higher processing temperatures, as increased heat can enhance the activation of their cleaning mechanisms. Consequently, any effort to reduce purge temperatures must be carefully evaluated to ensure cleaning effectiveness is not compromised. In some cases, however, chemical purge grades utilizing higher-viscosity carrier resins can offset lower temperatures by providing improved mechanical scrubbing action within the process.
This was not the first time the facility had examined its ideal purge temperature. When the purge program and its standard operating procedure (SOP) were originally implemented several years ago, 400°F was established as the preferred purge temperature to ensure sufficient activation of the chemical cleaning components. Because temperature increases can accelerate degradation of the host resin, the original decision was made after careful consideration of both cleaning performance and material stability.
As part of the current review, the team decided to challenge the existing SOP through a series of controlled trials. Purging was performed at progressively lower temperatures, including 390°F and 380°F, with additional trials planned at 370°F and 360°F. The primary performance metric was reduction in total purge-related downtime while maintaining acceptable cleaning results.
To support the lower-temperature trials, purge procedures were adjusted where necessary. Greater emphasis was placed on residence time and the application of more aggressive machine parameters to maximize mechanical cleaning action. The initial results demonstrated significant potential. Trials conducted at 380°F delivered cleaning performance comparable to that achieved at 400°F while reducing total purge-related time by approximately 50%.
Additional testing is planned to determine whether similar results can be achieved at even lower temperatures. The ultimate goal is to identify the "sweet spot" or "magic number" where purge performance and process efficiency are optimized, establishing a new best-practice purge temperature for the operation.
The Value of Continuous Improvement
Optimizing a purge process is not always about selecting a new material or implementing major equipment changes. Often, meaningful gains can be achieved by refining existing procedures and challenging long-standing assumptions. Fine-tuning purge SOPs can transform a good purge program into a great one, delivering measurable reductions in downtime, improved operational efficiency, and greater cost savings in today's highly competitive manufacturing environment.
Learn more about how to reduce production downtime and protect your profits with a purging compound.
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