Plastic, Chemical and Lubricant Industry Blog | Telko

Why use purging compounds in extrusion and injection molding?

Written by Telko Ltd | October 11, 2024

Purging compounds play a crucial role in maintaining the efficiency and quality of plastic manufacturing processes. Running purges is important for keeping production machines running for longer with less need for repairs. Choosing quality purging compounds that suit your applications helps to prevent color or composition anomalies in plastics manufacturing.

 

Why use purging compounds?

 

Purging compounds clean thermoplastics and molding machines to prevent color or composition anomalies. Plastics manufacturing rarely involves only one resin or colour. Running purges is integral, and choosing the right cleaning compounds and techniques is crucial.

 

Frequency of color or material changes vary a lot depending on the type of conversion and products manufactured. In injection molding there might be a lot of different products with various colors and materials produced in the same machine. In extrusion the case might be opposite with very little need for color or material changes. Cleaning compounds are effective in both cases improving productivity, sustainability, and quality.

 

When cleaned effectively, production machines run smoother for longer. They use less energy and generate less waste because cleaner machines consume less materials. With fewer anomalies, there will be fewer products that do not fit quality control requirements and end up in waste. Purging compounds can also be used in preventive maintenance to prolong equipment life and reduce the need for repairs and replacements on machinery.

 

 

What are the benefits of purging compounds compared to other cleaning agents and techniques?

 

Using a high-quality purging compound saves time and money. Using virgin resin might seem like an easy fix, but the neutral material needed to produce anomaly-free plastic can be up to ten times more than with purging compounds. Total down-time cost will also increase, as virgin resin needs up to three times more time to have the same effect.

 

We recommend the extremely easy to use and versatile Ultra Plast® purging compounds. Made in Switzerland by Ultra System, the purging compounds are made with the highest standards in manufacturing in mind. Less downtime, less waste and better end-product quality are achieved with 100% chemical action. A new formula improved with expanding agents makes it even more effective for hard-to-clean equipment.

 

Benefits of Using Ultra Plast® purging compounds:

 

  • Noticeably short purging cycle: no soaking time, saving time and money
  • Easy to use and requires few to no changes of machine settings, cleans at the processing temperature of the previous production batch
  • No waste due to purging, reduces downtime to minimum
  • User friendly: no smell or toxic volatiles. Also available as scented (lemon, on request)
  • Gentle care: no abrasive components, no solvents, no ammonium used, safe for equipment
  • Removes black spots and stripes
  • Long-term benefits: regular use keeps production equipment clean and in operation for longer, prevents oxidation of metal parts
  • Safe for humans: All components of Ultra Plast® purging compounds are approved for food contact (FDA / EU) and Generally Recognized as Safe (GRAS)

 

Common issues and best practices for using purging compounds

 

Common issues that arise in extrusion and injection molding are color changes, material contamination, and equipment wear. Using the right purging compounds can help overcome these challenges and maintain consistent, high-quality production.

 

When and how to incorporate purging compounds into the maintenance routine:

 

There are many ways to incorporate purging materials into the production cycle. It all depends on the type of machinery, age of machinery, mix of raw materials and colors produced on a given machine, product quality requirements and so on.

 

Typically purging compounds are used during difficult color or raw material changes. Some plastics converters prefer to use a highly effective purging compound e.g., once a month for deep cleaning and another purging compound for regular color/material changes in between.

 

What to consider when selecting the right purging compound for a specific application:

 

Selecting the right Ultra Plast® purging compound for your process and material comes down to raw materials in use. Most crucial factors are the type of conversion process and processing temperature of the material to be cleaned and the material following the cleaning cycle. There is a suitable purging compound for all processes and all materials.

 

To summarise, getting the most out of using purging compounds boils down to regular use. The long-term benefits of regularly using purging compounds are less energy spent, less waste generated, less down-time and extended time in production between dismantling and manual cleaning. This eventually leads to a shorter purging cycle and decreasing need to use purging compounds.

 

For more information on Ultra Plast® purging compounds, you can download the brochure or contact us.