Humidity and Moisture Control in Plastics Manufacturing in 2023
Moisture in the air can cause havoc in the manufacture of plastics. Condensation will begin to form on the moulds and plastic granules will begin to absorb the moisture.
There is no external factor as detrimental to the plastics manufacturing process, than moisture.
HOW DOES MOISTURE AFFECT the manufacture of PLASTICs?
Moisture causes issues with stored hygroscopic compounds
Condensation forms on plastic moulds
Condensation absorbs into plastic granules
Bubbles form in finished product
Clarity and crystalline structure of end product is of poor quality
Moisture in the air can be detrimental in the plastics manufacturing process. Condensation will begin to form on the moulds and plastic granules will begin to absorb the moisture
Thermoplastics and Moisture Absorption
Thermoplastics are used in injection and blow moulding operations. Thermoplastics (or resinous raw materials) are heated to increase the plasticity of the plastic materials. This plasticity allows the material to be shaped into forms using a mould.
Thermoplastics such as Polycarbonate, Nylon and PET are hygroscopic and extremely sensitive to moisture. While they are deemed a ‘dry’ material – by the time they get to the processor, they have absorbed moisture.
During this process a chemical reaction (hydrolysis) occurs which make the long polymer chains shorter. Long polymer chains are required to make high quality product. Short chains result in poor quality mouldings
CHILLED WATER METHOD IN PLASTICS maunfacturing
Chilled water is generally used to keep the mould cold; this allows the plastic item to form faster – which means faster production. The colder the surface, the faster the forming rates ergo, the higher the production volume.
However, when heat is mixed with cold it creates problems. Condensation begins to form on the mould’s surface which results in watermarks on the products. This is a highly undesirable outcome within the plastics manufacturing industry.
This condensation also corrodes moulds, guide pins and equipment. Plastic manufacture equipment, including moulds is very expensive. Damage to equipment requires repair or replacement, increasing operating costs and slowing (or stopping) production.
Heating method in plastics manufacturing
A simple solution in plastics manufacturing would be to increase the mould surface temperature. However, this increase means resin forming time is slowed, decreasing the volume of production and the quality of the end product (as defects often occur when forming time is increased due to longer exposure to condensation).
SO WHAT IS THE SOLUTION?
DEHUMIDIFIERS DESIGNED FOR THE PLASTICS MANUFACTURING INDUSTRY
A Desiccant Dehumidifier – Mould Dehumidification System
A Desiccant Dehumidifier used in the plastics industry is the ideal solution. A desiccant dehumidifier can achieve a consistent low mould temperature of 5° C or lower. It will remove the moisture from the air, eliminating condensation which allows for speedier cycle times leading to greater production rates. It also protects vital equipment. A dehumidification system safeguards the equipment against corrosion by keeping the moisture at bay.
Improved Plastic Products
A mould dehumidification system will eliminate the issue of shock cracks forming and it will improve the clarity and crystalline structure of the end product. Without water droplets forming on the mould, the surface finish of the product is highly improved.
Improved Raw Material Storage
A desiccant dehumidifier is also the optimal choice for the storage of raw materials. It is designed to eliminate moisture in the raw material before processing. Dehumidifiers are the ideal choice for storing any hygroscopic material.
Plastic granules, generally stored in silos can absorb moisture, so adding dry air to the storage space removes this moisture. The Dehumidifier does this by forcing ambient air through a desiccant wheel blowing dry air over the plastic granules.
Improved Mould Storage
Dry air can also be used when storing moulds. No need to put in time and effort in greasing the moulds - they are kept free from corrosion when the relative humidity is below 50%.
Avoiding moisture in the pneumatic system is also highly beneficial. Adding dry air will stop mould formation and stop the granules from sticking together.
No Effects from Weather or Changing Seasons
Ambient air (unconditioned air – air in its natural state) is unfavourable to many of the processes within plastics manufacture and has a direct effect on the end product. A desiccant dehumidifier is unaffected by external air temperature and can maintain a consistent temperature in all seasons.
If you would like to read more about Desiccant Dehumidification Technology, please visit our page.
We also offer Rental Dehumidifiers. A great way to test the technology before investing or for temporary use during the more humid months when ambient air affects your products more severely. Visit our Dehumidifier Hire page to learn more - we have seen many industries benefit greatly from the temporary use of dehumidifiers.
Service of Any Brand Dehumidifier. If you already have dehumidifiers as part of your production and/or storage process, please know Humiscope offer service and maintenance of any make and model dehumidifier. We have several technicians throughout Australia and pride ourselves on professional, friendly customer service and are always happy to do an onsite visit, obligation free. Please Check out our Dehumidifier Service and Maintenance Brochure
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