Say you need to go from running PEEK to ABS.
You need to fully remove the PEEK from your screw and barrel, or you will have serious contamination issues.
Once you complete your work order and before you change your processing temperatures, it is vital that you fully remove all the PEEK from your screw and barrel, or you will have serious contamination and layering issues that will cause carbon build-up down the road.
First, purge the PEEK with PX2 or PF Grade following our purging procedures and gradually lower the temperature to the lower end of recommended temperature range. This will give you the confidence to know your barrel has been fully cleaned and that you are not creating layering.
Next, chase the PX2/PF Grade with our general-purpose purging compound U Grade or our stronger scrubber EX Grade and continue to lower temps and purge thoroughly. Once you are at your processing temps for the ABS you can simply flush out the U or EX and begin production with confidence knowing you have fully cleaned the barrel.
This simple two-step process allows you to make the transition from a temperature range above 700°F for super-engineering resins and painlessly step down to a lower range for engineering resins with safety and control in mind. Reverse the order and purge grades if you need to step back up to the higher range once more.
This is not a process you should try on your own. The risks are simply too high. Work with an Asaclean® Purging Expert to develop the best procedures and Purge Program for your plant.
Benefits of a Two-Step Purge
There are serious benefits of using two purging compounds for these kinds of changes.
In the short term, you don't have scrap from start-up.
In the medium term, you don't have to tear down or pull screws. This saves you from 3-16 hours depending on the size of the machine.
In the long term, these time and cost savings add up to more sellable parts and reduce overall operating costs.
While it may seem like more work, using a combination of two grades while following some easy instructions can save you hours of downtime and maintenance, as well as dramatically reduce your scrap.