Thick film heating elements
Field of application
- various kinds of contact heating
- cooking plates and boards
- electrical household appliances
- water heating in storage and instantaneous water heaters
- water heating in washing machines
- water boiling kettles, deep fat fryers
- irons, cookers
These heating elements are intended for contact heating of flat surfaces and for heating of liquids through a flat wall. Compared with an ordinary tubular heating element, a heating element on a sheet metal provides substantially better heat transfer into a flat wall. These elements can also be of benefit in applications, where low thickness of the heating element is important.
Considering the application of thick film elements, a consultation with the Technical Department of Backer Elektro CZ is highly recommended for detailed specification of particular requirements.
Information about Thick film heating elements
Thick film heating elements are manufactured in a completely different way than ordinary tubular heating elements. A thick film heating element consists of a stainless steel or ceramic substrate (plate), on which an insulation layer (meets the requirements for dielectrical strength) is printed, then a layer of resistive paste, followed by a contact and connective layer, and finally all these layers are covered with top enamel layer (providing just protection against mechanical damage, does not meet the requirements for dielectrical strength. The individual layers are applied by screen printing and each layer is dried and fired afterwards. Maximum protection from dirt and dust is essential through the whole production process. Production runs in air-conditioned areas meeting the requirements for rooms with high air purity class.
Thus precisely manufactured thick film heating elements feature a quick temperature rise, an extremely low thermal capacity and minimum temperature fluctuations. Their high efficiency of 70 - 95% depends on the mode of operation (direct or indirect heating).
At Backer Elektro CZ, substrates made of stainless steel according to standards AISI 430, DIN 1.4016 are used. Test with stainless steel AISI 304, DIN 1.4301 were carried out as well. The substrate (printing area) must be flat, but can be of various shapes and can contain openings manufactured in advance (before the printing process).
The elements operate at standard line voltage (up to 400 V). Thick film heating elements feature very high surface power density(up to tens W/cm2). Nevertheless, their operation conditions should be adjusted according to the particular application - adequate heat transfer should be provided so that the surface temperature does not exceed 300 °C.
Thick film heating elements feature a significant PTC effect (its resistance rises with rising temperature, so its power decreases consecutively). Thus, resistance at room temperature and nominal voltage are specified as technical parameters for thick film heating elements.
These elements are manufactured within 15 % tolerance of resistance (power).
- SCHEMATIC VIEW OF A THICK FILM HEATING ELEMENT
Technical data required for specification of a new type of thick film heating element
Costs for manufacturing preparation of a thick film element with a new patters are about 40000 to 50000 CZK, including production of test series (0-series).
The following technical specifications must be clarified and approved by the customer before starting the design of a new thick film element:
- operational voltage
- power rating at operating temperature or at room temperature
- operating temperature
- dimensions and shape
- fixing of the heating element onto the heated surface
Technical data required for manufacturing of a standard type of thick film heating element
When applying a standard heating element from our assortment, there are no costs for development of a new type. The following technical specifications must be clarified and approved by the customer for optimisation of heating method for the particular application (eg. heating of hot plates, heating of vessels containing various substances etc.):
- dimensions of the area for fixing the heating element(s)
- operational voltage (230 V, 3 x 400 V star- or delta-connected, etc.)
- total power rating
In case that the total required power rating is not known, the following parameters must be specified:
- operating temperature
- time for reaching the operating temperature (start-up time)
- type of heated material (eg. aluminium plate, stainless steel vessel with water)
- dimensions of heated material (eg. aluminium plate - length, width and thickness; stainless steel vessel - diameter, height, wall thickness, bottom thickness, volume of heated substance).
Delivery conditions for sample quantities and custom-made orders
- standard element listed in this catalogue and being on stock – immediately
- standard element listed in this catalogue, not on stock - within 3 - 4 weeks
- an element not listed in this catalogue – 2 to 3 months
Delivery conditions for higher volumes on request.
Consultations
Tel.: +420 463 030 610
Fax: +420 463 030 649
e-mail: ttt@backer-elektro.cz