Tips for Selecting a Commercial Purge Compound

1. What resins are you working with?

Commercial purge compound (CPC) manufacturers have grades designed to purge specific types of resins. In some situations a company may be able to use only one grade of CPC to solve all their purging issues. Also, manufacturers of CPCs typically offer multi-purpose grades that work well on a wide range of resins. The multi-purpose grades of CPCs are beneficial to custom molders that are working with dozens, if not hundreds of different types of resins. Moulds Plus International offers the Ultra Purge 5050 which works well at purging resins with an operating temperature ranging from 364°F to 665°F. However, in other scenarios it may be best for the plastic processors to use multiple grades of the CPC in order to most effectively clean their machines.

2. What type of plastic processing machinery do you have a need to purge?

Injection molders are the most common type of plastic processor using CPCs. However, most CPC manufacturers have grades to offer all thermoplastic processors. CPCs offer the same benefits to companies involved with extrusion, blow molding and blown film as they do to injection molders. Specific grades of CPCs may be required depending on the type of machinery that is needed to be cleaned.

3. What type of issues are you experiencing?

The five basic situations for which a CPC is required are dark to light color changes, carbon removal, material change and machine shutdown/start up. Manufactures of CPCs will many times customize procedures based on the type of issue(s) the plastic processor is having. In some scenarios the CPC technical representative may recommend a specific grade of CPC based on the issues that the company is experiencing.

4. Amount of purge compound required

Commercial purge compounds use different technologies and therefore the amount of CPC that is needed to clean a machine differs. For example, Ultra Purge is a chemical type of purge compound that typically requires one barrel capacity to clean the machine. When evaluating CPCs it is important to monitor the amount of each purge that is required to sufficiently clean the machine. The more CPC that is used the more expensive the purging process will be. Having knowledge of the quantity of CPC required to clean the machine will allow companies to make a better informed decision on choosing a CPC. The combination of the price per pound of a CPC with the amount necessary to purge will help determine the best CPC to use. Sometimes the lowest priced purge per pound ends up being the most expensive option.

5. Performance (downtime and scrap)

The sole purpose of using a CPC is to reduce the downtime and scrap. When conducting trials it is important log the data for each of these attributes. Using a data collection form can be very helpful with this task. Downtime should be designated as every minute the machine is not making a good part that can be sold to its customer. Scrap is determined by adding up the total amount of contaminated parts along with any purge piles that are made. Typically companies accumulate a greater financial loss due to excessive downtime during a purge as opposed to the scrap. Ultra Purge customers typically see between a 50-80% reduction in downtime and scrap compared to using resin to clean the machine.

6. Ultimately….Price Per Purge

When you get right down to it deciding on the correct purge is very simple and straight forward. Essentially what method of purging saves a company the most amount of money? The downtime, scrap, amount of CPC required and price of CPC data is collected and then inputted into a cost analysis equation/calculator. The commercial purge compound that demonstrates the lowest price per purge will be the right choice for you.

Contact Moulds Plus International today for a free sample of Ultra Purge and see how we can it can help you with your purging compound needs.