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IR Sensors in extrusion coating

Rotomolding and Slush Molding

Rotomolding and Slush molding are unique plastic processing techniques used to manufacture large plastic products, including: Rotomolding products, such as water and chemical tanks, automotive fuel tanks, children's play equipment, and canoes, in addition to Slush Molding products, such as automotive interiors and dashboards.

The processes involve forming the plastic product in a large heated mold. Polymer granules are added to the mold, which melt and form a skin on the internal surface of the mold as it is rotated inside the oven. After thermal processing, the mold is cooled and the finished formed product is removed. Different polymers can be used in Rotomolding, such as Polyethylenes (LDPE, HDPE), ABS, Nylon, and Polypropylene. Each polymer has its own unique thermal characteristics, so the process heating cycle needs to be optimized for the polymer used.

Application Need 

The Rotomolding and Slush processing procedures are temperature critical, during both the heating and cooling cycles. To guarantee that the plastic product has the required physical strength, appearance and life expectancy, it is critical that the polymer experiences the correct temperatures to accurately perform polymer melt, fusion and crystallization of polymeric structure. Processing requires the ability to monitor the internal mold, mold surface and oven ambient temperature (in real-time) to allow control of the process cycle and determine exactly when critical process temperatures are achieved.

Benefits to the customer 
  • Monitor and control entire heating and cooling cycle, to avoid quality issues, such as poor impact resistance, structural defects (bubbles, pinholes) and color degredation
  • Identify exact point when the process has reached critical peak temperature (mold surface and core), allowing live process control to optimize throughput
  • Control of cooling process prevents issues, such as warpage and difficulty in removing product from the mold
  • Process monitoring tool allows the accurate design of new molds when starting up new processes for either new products or different polymers
Thermal Profiling Systems
  • Multiple channel RotoPaq RF system provides detailed and real time process temperature information from internal mold, mold surface and oven
  • RotoPaq system is portable and can be efficiently interchanged from process to process, or even plant to plant
  • Thermal barrier options allow for the most demanding of applications, or if mold cooling involves water showers

Literature and other resources

Video 

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