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Induction brazing of refrigerator parts

EFD Induction equipment is used at some of the world’s largest consumer refrigerator manufacturing facilities as a superior alternative to traditional flame brazing of tubing connections, as well as for heating pre-painted panels prior to bending. Tom Brown of EFD Induction USA explains more about this safer, more consistent, repeatable method of heating.

 

Refrigerator brazing

 

Since induction heating is “flameless heating”, meaning that no open flame is used, it is safe for the operator.

Heat source related injuries are eliminated because there is no open flame, and the induction heating coil is cooled internally by flowing water. Therefore, the coil does not get or stay hot during and after brazing. Even though induction heating is generated by electricity, the heating coils used in conjunction with EFD Induction Minac power units provide output voltages that are less than 50 Volts, typically 38 – 40 Volts, which is in a safe operation range. Tube type induction heating equipment, on the other hand, generates coil voltages of over 400 Volts.

 

Another benefit of “flameless” induction heating is that the heat source does not damage surrounding components such as pre-painted surfaces, freezer and refrigerator cabinet enclosures or plastic electrical connectors and wiring bundles. There is no need to pre-place heat shields to prevent damage as is typically done with flame brazing. Because of this, brazing cycle times can be reduced due to the elimination of this manual operation.

 

Due to manufacturing issues associated with operator turnover, it is sometimes difficult to get consistent, repeatable braze joints from many different operators. Flame brazing is a skilled operation that is highly operator dependent. Because of the dependency on the operator, much more cost is incurred due to higher wages, inconsistent usage and/or overuse of expensive brazing alloys, as well as re-work due to a higher rate of leaking joints. Induction heating used together with pre-placed brazing rings eliminates these issues. Since brazing cycles can be pre-programmed into the Minac power unit controller, the same heating cycle will be provided every time.

 

The EFD Induction Minac is unique and ideally suited for use on high volume, mass produced refrigerator production lines as well as for use in manufacturing low volume, custom built units. EFD Induction equipment features hand held transformers that allow the induction heating coil (heat source) to be brought directly to the braze joints, as opposed to traditional, fixed induction equipment. Due to the use of IGBT transistor technology and innovative engineering, Minac induction power units are compact and take up much less floor space than traditional

induction heating equipment. Also, the Minac comes in twin-output models that provide two separate heating outputs that can be used independently at the same time. Full unit output power can be provided to each output. This option reduces equipment costs and the amount of plant floor space required.

 

Brazing is not the only application of induction heating in refrigerator manufacturing. It is used for adhesive bonding and paint drying. And is widely used to heat pre-painted sheet metal panels prior to edge bending. This method allows the metal to be bent without cracking the pre-painted surface because induction will heat the metal, making the paint pliable.