What are Plastics Thermocouples?

Right Angle, Bayonet Style, Plastics Thermocouples

The term "plastics thermocouple" refers to a style of thermocouple designed and used by the plastics, packaging and rubber industries.  They are installed on injection molding, thermoforming, vacuum forming, and extruding equipment to accurately sense the temperature of the plastic molds and nozzles. While there are a variety of configurations of plastics thermocouples - such as bayonet, washer style, shim style, nozzle, and right angle - their basic components remains the same.

In most cases, plastics thermocouples are ANSI type J or type K calibration. Type J or K lead wire is available in a variety of insulation materials and protection options, such as high temperature fiberglass, PVC, stainless steel braided fiberglass, or stainless steel flexible armor cable. Electrical connections are most commonly bare leads, male thermocouple jacks, female thermocouple plugs, or spade lugs.

Bayonet designs are straight or right angle, and use industry standard bayonet fittings that easily retrofit most injection molding and plastics processing equipment. These fittings allow for adjustable depth and are spring loaded for maintaining goos contact with the media. Washer and shim style thermocouples weld or crimp the thermocouple sensing junction right to the washer or shim.

Bayonet thermocouples use a tube and wire design utilizing stranded thermocouple cable through out the probe. The metallic probe is made of 301, 304 or 316 series stainless steel. The thermocouple can made with a grounded, or ungrounded junction. A grounded junction is welded to the tip of the probe and, while it has very fast response, it can conduct electrical noise back to the instrumentation. An ungrounded junction is isolated from the metallic probe, and prevents electrical noise transmission. However, ungrounded junctions are slightly slower to respond to temperature changes.

For more information on plastics thermocouples, contact Duro-Sense by visiting https://duro-sense or by calling 310-533-6877.