A purge on costs

Since October 2011 Plastribution has been able to offer its customers purging agents from Aquapurge.

We currently hold stock of their Barrel Blitz Universal (BBU) purging compound within our warehouse network; other Aquapurge products are available on request and with the relevant technical support.

With many manufacturers committed to a ‘Just-In-Time’ or ‘Lean Manufacturing’ operation, a growing number of moulders are now making more frequent tool changes and carrying out shorter production runs to accommodate compressed lead times. Frequent changes in material or colour requires the cleaning, or purging of processing equipment, to clear material lodged within them from previous runs. Resin lost in purging can often be the largest single cause of scrap material and is also a major factor in lost machine time.

Purging compounds are designed to make this transition take less time, with less lost resin, and with lower cost.  Manufacturers can make more productive transitions if the purge compound quickly and completely removes the previous material from the machine and tooling. Recognising this development, Plastribution can now offer its customers direct access to Aquapurge’s range of purging compounds.

As with other Aquapurge products, their Barrel Blitz Universal purging agent increases the productivity of plastic processing equipment by enabling rapid material and colour changes and the effective removal of carbon.

John Steadman, technical director at Aquapurge, explains more in a recent Q&A:

Plastribution: Why should moulders consider Barrel Blitz Universal?

JS: Barrel Blitz Universal will keep screws, barrels and nozzles in pristine condition. Each time a moulder uses BBU for colour or material changes, he is giving his machine a deep scrub back to its original screw, barrel and nozzle profiles.

Plastribution: Why is this so important?

JS: At the end of the day, getting back to the original screw profile means more profit because the process is ultimately more repeatable. But it’s how it gets there that is exciting. If we forget for a moment the savings attributable to the reduction in rejects caused by specks of carbon or colour, for instance, and just focus on screw profile, it is amazing how many issues in production can be resolved by keeping the screw clean and constant to how it was originally manufactured.

Plastribution: Can you provide an example?

JS: Certainly! For instance, if you get a build-up of carbon or plate-out, it is likely not going to be uniform across the screw, but will often start at the compression zone and get worse through the metering zone.

This reduces the depth of the metering zone, which means that you are trying to force the same amount of material from the feed zone through a smaller volume metering zone. This will either succeed, or you will get a measure of screw slip which results in an extended screw back time.

In either case you get an increase in shear placed on the melt, which in turn results in increased melt temperature, longer cycle times, different flow characteristics through the mould, voids, flash, splash, gassing and so on… All of which equals rejects and wasted time!

Plastribution: And ultimately less efficiency?

JS: Precisely! At the end of the day you are hampering yourself with a reduction in the processing window and extended set-up times.

This means less machine utilisation, lower output for the same or higher cost and, at the end of the day, less profit. Alternatively, by using Barrel Blitz Universal, moulders can maintain their machines in the same pristine condition as they were in when they were delivered, thereby increasing both their utilisation and output.