TEMPERATURE MEASUREMENT

Blown Film Extrusion

Ensuring High Quality Standards

• Similar to injection molding, the molten mass is pushed out of the extruder – however, in this case not into a die, rather through a die with a ring nozzle. The resulting film tube is then pulled vertically and blown up in the process. During this process air is used to cool the tube both inside and out.
• From the moment the molten mass emerges from the nozzle, the temperature of the film tube needs to be measured at various points in order to ensure the characteristics and quality of the product.

Process temperature

• 195 °C to 220 °C

Rotational Molding

Enabling Quick Corrective Measures

• The rotational molding process is a specialist technique used in the manufacturing of plastic parts and is primarily used for larger objects. Here a negative mold is fi lled with a powdered or liquid raw material such as PE or PP and then sealed. The mold is then heated in an oven to a maximum of 320°C and rotated biaxially. This causes the material to stick to the mold, layer by layer. The mold is subsequently cooled in a chamber and the plastic part removed. Upon opening the mold, the product is thermally tested to allow the production process to be readjusted if necessary.

Process temperature

• up to 320 °C

Thermoforming

Precision and Reliability

• To avoid local burning and crack formation, an even temperature of the material is of importance during thermoforming processes. Thermal imagers are used to retract the temperature regime of equipment. Punctual measuring pyrometers take care of the temperature control during production by monitoring defined measurement points.
• New manufacturing techniques and combinations of materials are being developed all the time, particularly for demanding application areas such as automotive engineering. Continuous fiber-reinforced thermoplastics, which are extremely strong but very lightweight at the same time, are a typical example of this kind of innovation. Ensuring the quality and the proper production process there has to be a reliable and precise temperature measurement.

Procedure

• Sheets or unrolled film made from thermoplastic polymers are fed into the molding machine and then, in the first step, warmed up on both sides until the semi-finished product is completely melted. When a predefined temperature has been reached, the film is then sucked into a tempered mold using a vacuum. Only when the product has cooled down again and is dimensionally stable is it transported further to be finished.

Process temperature

• 110 °C to 230 °C