induction heating coil making principle
Sep. 21, 2018
Induction heating coil making
The heating result depends on not only current of induction coil, but also the shape of the induction coil, the number of turns, leads of coil, and material & shape of heated parts. To optimize power of induction machine, the most important is to design coil according to part’s material and shape.
In general, Induction coil design should follow following principles:
1. Coil shape should be based on the shape of the heating surface of the parts. Make sure copper tube of coil and the heating surface of the workpiece in parallel and the current flow direction of adjacent turns should be consistent.
2. To determine turns of coil
The following situations should adopt double turns or multi-turns:
2.1 Non-magnetic materials such as copper/brass and aluminum, etc.
2.2 Parts diameter ≤20mm
2.3 Plane heating
2.4 heating by external magnetic field
3. Adjustment of distance between coil and part following principles:
3.1 for small parts distance between coil and part should be controlled in 1-3mm.
3.2 For larger parts distance between coil and part is determined by the following principles:
l When the power rate of machine adjusted to the maximum and the current has also reached its maximum rate but heating very slowly, you should reduce the distance between coil and part or increase number of turns of the induction coil.
l When the power rate of machine adjusted to the maximum but the current can’t reach its half rate, you should increase the distance between coil and part or reduce number of turns of the induction coil.
4. For heating by external magnetic field (e.g. plane heating, inside diameter heating, etc.) or heating of non-magnetic material, to use different shape of flux concentrator can greatly increase output power of machine. Then the output power can be optimized.
5. Make coil leads as short as possible because long coil leads will increase energy loss of machine. E.g. for SSF, coil lead length is about 200mm but HFP is about 150mm
6. If coil shape determined by heating method and reduce heating efficiency, consider machine with higher power.