Square Cartridge Heaters

Square stainless steel tubular heaters BASE-flex (1.4541) are a reliable industry standard for the use in heating platens and manifolds. In contrast to traditional tubular heaters with a round section which have to be bent by machines, square BASE-flex can be fitted into any rectangular groove with simple hand tools. Moreover, the square shape results in a bigger heat emitting area of up to 80% compared with a corresponding round section. Finally, the easy manual mounting saves the usually high technical expenditure for casting-in / soldering / cementing of bent round tubular heaters. A soft version of the BASE-flex, the NICKEL-flex (2.4068) is available as special execution. Due to the soft, easy to form nickel material, the NICKEL-flex is suitable for manual mounting with hand tools in round sections, too. Furthermore, Nickel has a better capability to conduct heat compared with stainless steel.

HotCoils have a larger cross-sectional area and are thus capable of greater power than MicroCoils. For this reason they are used in hot runners with adequate space and where high heat densities are required. Owing to the large number of variants and for cost reasons, the sheath material for HotCoils is stainless steel - the standard for the market and thus also for Freek. HotCoils are large enough that thermocouples can be integrated into them. Our standard here is Type J (Fe-CuNi; red/blue), while Types J and K are also available conforming to the IEC and ANSI standards (see colour codes). Since the measurement point of a built-in temperature sensor is situated in the heater and never where the heat is actually required, a HotCoil with a thermocouple makes particular sense where the application allows the use of larger processing (temperature) windows or where the installation location or the design requires protection against overheating.

Occasionally also these terms are used for cartridge heates: heating cartridge, insertion heaters, spiral cartridge heaters. As a rule cartridge heaters consist of a cylindrical stainless steel tube and thus provide a high corrosion prevention. There is a heating wire inside which is wound onto a ceramic core. The number of coils varies depending on the power. In order to avoid a short-circuit, the cartridge heater is filled with magnesium oxide and compressed afterwards. Highly compacted they reach a surface watt density of up to 50 W/cm² and withstand highest stress. In the plastics industry cartridge heaters are used in hot runners in order to temper thermoplasts during injection moulding processes. Other areas of applications for process heat are e. g. packaging, diecasting or continuous casting in which zinc or aluminium are processed. Further applications are to be found in mechanical as well as medical and laboratory engineering.

Advantages of Heating Plates with Square Cartridge Heaters: -> Simple plate manufacture due to rectangular groove geometry, no deep-hole boring -> Simple heater installation by bending and pressing along the plate surface -> Complex plate geometries with bores and openings -> Optimal heat transfer due to 75% surface contact -> No casting with heat conductive compound -> Uniform temperature profiles due to thermally optimized groove layouts/power distribution and utilization of insulation plates -> high process temperatures (up to 450°C in aluminium, up to 700°C in stainless steel) Example "Heated Stamp": D=100 mm out of tempered tool steel up to max. 700°C continuous temperature. Fitted with 2 Square Cartridge Heaters 1500 W/ 230 V, 4,5 x 4,5 mm x 600 mm, with 50 mm unheated at the termination end. Annealed and formable with a nickel sheath, resistant up to 850°C surface temperature. Connection by fibreglass insulated pure nickel high-temperature leads (max. 500°C)