Sintering/Diffusion Bonding

Sintering is the optimal process for producing multi-coloured rings, mostly sold as wedding rings. Metals are processed under pressure and at temperatures below the solidification point. The fusion between layers has the same durability as the metal itself. Pre-manufactured rings can be easily resized.

Indutherm offers two methods of sintering:

The sintering kit for installation into existing casting machines or special sintering machines, the SU series.

The Sintering Kit

The sintering kit can be installed into existing Indutherm casting machines of the type VC 400/500/600/600V and in all continuous casting machines. The kit is ideal for the occasional diffusion bonding job and for smaller series production. Only a few minutes are needed to install/remove the sintering kit.

Rings with up to 9 layers produced by a customer

Main benefit of this method:

The pressure is generated pneumatically and not mechanically via a threaded spindle. This means that there is no risk of graphite parts breaking as a result of heat expansion.
The sinter kit can be used for the occasional diffusion bonding and for small series production.

Sintering Machine SU 300

The SU 300 is suitable for larger scale production. It has been specifially constructed for diffusion bonding in factories which specialize in the manufacturing of wedding rings. An excellent quality of bi- or multi-coloured wedding rings is guaranteed.


  • With the sintering unit SU 300 process can take place under vacuum, which is important for alloys with manganese component
  • Process can take place under inert gas
  • Straightforward installation / removal of the rings
  • Approximate duration of process: 5 minutes
  • Depending on the thickness of the rings, up to 6 rings can be processed simultaneously

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All machine descriptions and technical data published on this site make no claim to be complete. They are subject to change and therefore they are not basis of contract.

Sintering Machine SU 450

The new SU 450 is equipped with a highly sensitive sensor system, which permanently controls the reduction of the rings and provides real-time information about the reduction values on the display. The temperature is regulated automatically and very precisely close to the solidus temperature, exactly until the reduction begins.
As soon as the pre-defined reduction value has been reached, the process stops automatically and so too much deformation can be eliminated (depending on composition and alloy the pre-defined reduction value lies between 0.1 mm and 0.3 mm).

The “Sensor-Control-System” considerably reduces the time and material required for the production for two major reasons: firstly because the process parameters can be defined quickly and without making lots of test rings; and secondly because the quality of the sintering process is constantly very high. Therefore the finishing effort is reduced, as well as the loss of material, which occurs during subsequent diamond dressing or turning.


  • program control for 100 different process cycles
  • LCD display
  • sensor control system for permanent process control
  • real-time display of the reduction
  • no long-winded preliminary tests
  • less finishing effort and loss of metal

Easy handling of the sintering kit and the sintering machines

Metal connections in excellent quality

Dummy Bild. Klicken zum Ersetzen

Please click to enlarge.

Many tests were effected with the rings produced this way: They were drilled, milled, perforated and enlarged up to 18 sizes.

Afterwards the rings were sawed to check the section under the microscope. As a result of the tests we can confirm that an enormous reliability of the sintering can be guaranteed.

SU 450 flyer for download