Purge compounds offer improved cleaning efficiency compared to purging with resin, resulting in less scrap and machine downtime. Still, people often mistake the price comparison with resin and deem purging “expensive.” The truth is that the efficient usage of an adequately recommended grade of purge can’t be expensive when, in fact, it’s quite the opposite: it saves the company money. Satisfied users of purge across the globe who are fortunate to find a purge with the proper cleaning, low residue, and efficiency characteristics can quickly see that paying for the purge comes with added savings in reduced scrap and increased machine production time; in other words, it should always pay for itself and still yield savings on top of that.
The entire idea of purge usage rests on the cost analysis performed when comparing any two purge methods, whether it be using virgin or regrind to purge or a commercial purge compound; any two ways require identical measurables to define cost-effectiveness: machine time spent/lost (including from screw pulls / teardowns for manual cleaning), purge or resin paid to clean the machine, total scrap, and resin before next good part, and their corresponding rates (costs). This way, you can easily compare two methods and their related “total purge costs,” and the lower cost option wins. This data can only be provided or analyzed by teams that lead production floors and are responsible for running an efficient operation. If the purge is not more cost-effective, it is not recommended.
That said, if purge is used wastefully or recommended machine procedures are not considered to reduce quantity per use, then any cost savings that otherwise can be had become at risk. Another issue to avoid is the use of the wrong grade of purge. For example, you might use a specific purge successfully on jobs A, B & C but now need something with more cleaning power, or now need to purge through hot runners or die heads, or maybe even begin a shutdown/sealing purge for a new series of jobs with thermally sensitive resins, etc.
Suppose you don’t update the purge supplier on the applications. In that case, the risk is presuming you have the correct grade and possibly running a larger quantity of current grade than you would otherwise with a more appropriate grade. If it fails, you may not know if there is a better option to consider for evaluation. These can undoubtedly become expensive events, but not to be blamed on the purge itself. This can be no different than with any other product or process that is not qualified correctly or where proper procedures (SOP) are not in place.
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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