Miniature tubular cartridge heatersMiniature tubular cartridge heaters
August 23, 2008
New RP tubular cartridge heaters are used to heat nozzles in hot runner systems and can also be used by injection molders for retrofitting for special tooling and molds. The heaters are coiled cylindrically to obtain a good thermal transfer and are fitted to the nozzle by pressing an additional tube onto the coils or by casting them onto the nozzle. The circular-shaped RP 1.8 has a diameter of 1.8 mm; the flat, oval-shaped RP 1.4 x 2.3 has a section of 1.4 by 2.3 mm.
The RP 1.8 is equipped with an integrated thermocouple. The electrical connection of the heater consists of PTFE-insulated leads coming out of the sheath at one end, while the thermocouple connection at the other end of the sheath is made of glass-fiber-insulated compensation leads. The heater can be coiled at a minimum inner diameter of 7 mm, which allows the heating element to fit almost any nozzle body. The RP 1.4 x 2.3 has a single-phase connection sleeve with a diameter of 4 mm and a sleeve length of 14 mm. At a heated length of 500 mm, both heaters can produce a performance of 200 to 300W at a voltage of 230V. (The maximum straight length is 1200 mm.) In order to install the connection of the leads and to prevent them from overheating, a cold end of at least 50 mm is required. The heaters can be charged with a maximum current of 4A at a leakage current of less than .5 mA. The dielectric strength in straight execution for heating elements without thermocouple is 1250V, while with thermocouple it is limited to 600V between thermocouple and heater. Both heaters can be assembled coiled onto a brass or alloy sleeve with a bore hole tolerance of .03 mm. For the mounting of the heater, a stainless steel tube is compacted onto the coil, which enables the whole assembly to be used as a ready-to-use cylindrically shaped heater at a thin-wall thickness. The RP 1.8 has a wall thickness of 4 mm and the length can be chosen upon request. Prices in quantities of 100 for the RP 1.8 without thermocouple start at about $60 each; $74 with thermocouple. The RP 1.4 x 2.3 heaters start at about $77. Quantity discounts are available. Turk Hillinger
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