Compounders and Processors could enhance productivity and quality by Purging of Equipment

Techno - commercial information on plastics Industry - News on Plastics Industry - Plastemart.com

Manufacturers often make several different products on the same equipment. To achieve consistently good quality of different products, the equipment is required to be clean and free from the previous product processed. The products could be different and could vary in various aspects; colour, resin, formulations or melt viscosity.

While good planning of the manufacturing operation could help in reducing the production of waste material that is generated between the change from the first to the next product, a complete clean up of the equipment would be required for changeover to a very critical product. The production loss due to complete clean up is quite significant and negatively contributes, heavily to the Profitability of the compounding operation.

There is, however, an alternative method available, that could reduce the downtime of processing equipment. Special compounds known as "Purging Compounds" are commercially available. This compound is used to remove either colour, resin or formulation before a changeover or shutdown of the compounding line. Even if the shutdown is required, the cleaning of equipment with the Purging Compound reduces downtime very significantly.

There are essentially 3 types of Purging Compounds available :

		Chemical Purging Compound; this type of compound contains a chemical that reacts with the compound when soaked for some time at elevated temperatures. The chemical cleaning can be very efficient. Only the harmfulness of bye-product gas, that is inevitably generated, could cause some damage to the compounding barrel/screw.
		The second type of Purging Compound utilizes the mechanical scouring action of inert fillers that are blended with either universal resin or with specific resin system. These abrasive fillers could cause wear on the screw/ barrel on long usage.
		There is another type of Purging Compound that uses the principle of mechanical cleaning using non-abrasive granules. These granules are soft from outside but are solid inside. Their mechanical action helps in cleaning the equipment without wearing screw/barrel. These non abrasive Purging Compounds provide the optimum benifits of cleaning the system without affecting the screw/barrel and are therefore the best purging compounds that are commercially available in the market.