Posted to News on 22nd Aug 2014, 13:24
Infrared temperature measurement in thermoforming
The process of thermoforming a plastic sheet depends critically upon temperature. Calex pyrometers have been used by manufacturers to control heating and cooling in thermoforming for more than 10 years, resulting in increased product quality, consistency and production rates, and a reduction in heating costs.
Forming temperatures typically range from 120degC to 370degC. Precise temperature control is required, and the high-performance PyroMini infrared temperature sensor is suitable for the task.
Infrared heaters heat the plastic sheet; a temperature sensor is used for each heating zone to ensure it is heated evenly. For the best control, at least 10 points should be measured: all four corners and the centre, on the top and bottom surfaces.
The sensing head is positioned between the heating elements. High ambient temperatures mean that PyroMini JA (up to 120degC ambient) and HA (up to 180degC ambient) models are most suitable. No cooling is required for the sensing head.
In this process, the production rate is often limited by the cooling time. The PyroMini monitors the surface temperature of the formed part as it is cooled with an instantaneous 240ms response time, so the operator or control system can see immediately when the part is cool enough and remove it quickly.
An optional touch screen display provides a large, bright indication of measured temperature, two alarm relay outputs, and data logging to a MicroSD Card. The sensor is fully configurable via the touch screen. For connection to a PLC or temperature controller, two output types are available: 4 to 20 mA or RS485 Modbus.
Calex can also provide other thermoforming temperature systems ranging from a single sensor with a PID controller, to a digital network of hundreds of sensors, with display, control, alarm, analogue output and data acquisition functions. For more information, see this application note. The PyroMini is available to order now. For more information email [email protected], or visit the website at www.calex.co.uk.
