What is a "Plastics Thermocouple"?

Plastics extruders and injection molding machines are the machineries used in the plastics industry to produce plastic products.

A plastics extruder is a machine that melts plastic pellets or granules and pushes the melted plastic through a shaping die to form a continuous profile, such as a pipe, tubing, or window frame. This process is called extrusion. Extruders make a wide range of products, including plastic film, sheeting, and tube.

On the other hand, an injection molding machine injects molten plastic into a mold, where it cools and solidifies to take the shape of the mold. This process is called injection molding. Injection molding makes a wide variety of products, including plastic bottles, containers, and other household items.

Both machines have a barrel and a screw that melts the plastic and pushes it through the equipment. The barrel heats to a specific temperature, and the screw rotates, mixing and melting the plastic. The melted plastic is forced through the nozzle and into the mold or die.

Temperature control on the barrels and nozzles of plastics extruders and injection molding machines is crucial for producing high-quality, consistent plastic products.

The barrel and nozzle are the machine parts where the plastic heats to the melting point before extruding or injected into the mold. If the temperature is too low, the plastic may not melt fully or have the correct viscosity for proper processing, resulting in defects in the final product, such as voids, weak spots, or uneven surfaces.

On the other hand, if the temperature is too high, the plastic may degrade, resulting in reduced strength, discoloration, and other defects. Additionally, overheating the plastic can cause it to degrade, which can release harmful volatile organic compounds (VOCs) into the air and contribute to air pollution.

Overall, precise temperature control is essential for ensuring that the plastic heats to the correct temperature and that the final product has the desired properties, such as strength, flexibility, and appearance.

A thermocouple is a device used to measure temperature. A "plastics thermocouple" refers to a thermocouple used in the plastics industry, used to measure the temperature of plastics during various stages of the manufacturing process, such as during injection molding or extrusion. This information ensures that plastics experience the correct temperature, which can affect the properties and quality of the final product. Plastics thermocouples also monitor and control the temperature of the injection molding machines' barrels and nozzles and monitor the plastic's temperature during the extrusion process.

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Thermocouples Used in The Plastics Molding and Forming Industry

The term "plastics thermocouple" refers to a thermocouple used in the plastics, packaging, and rubber industries. Plastic thermocouple installations include injection molding, thermoforming, vacuum forming, and extruding machines to precisely measure the temperature of the plastic molds and nozzles. While plastic thermocouples come in various configurations such as bayonet, washer style, shim style, nozzle, and right angle, their essential components remain the same. 

Plastic thermocouples are typically calibrated to ANSI types J or K. Thermocouples lead wire comes in a variety of insulation and protection options, including high-temperature fiberglass, PVC, stainless steel braided fiberglass, and stainless steel flexible armor cable. Bare leads, male thermocouple jacks, female thermocouple plugs, or spade lugs are the most common electrical connections. 

Bayonet designs are straight or right-angle configurations, with industry-standard bayonet fittings easily retrofitted to most injection molding and plastics processing equipment. These fittings have adjustable depth and are spring-loaded to contact the media. The thermocouple sensing junction is welded or crimped directly to the washer or shim in washer and shim thermocouples. 

Bayonet thermocouples have a tube and wire design with stranded thermocouple cable running the length of the probe, and a metallic sensor is a stainless steel from the 301, 304, or 316 series. The thermocouple has either a grounded or an ungrounded junction. While the probe has a speedy response, a grounded T/C junction welded to the probe's tip can conduct electrical noise back to the instrumentation. An ungrounded junction is isolated from the metallic sensor and prevents the transmission of electrical noise. On the other hand, Ungrounded T/C junctions are slightly slower to respond to temperature changes.

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.