Quality of the parts
Better metallurgical results, improved mechanical properties, distortion control... ECM’s innovations and R&D work have highlighted ways to improve the quality of the parts thanks to heat treatment and gas quenching. And the results are measurable on our ICBP® installations!
With ECM’s Low Pressure Carburising solutions, oxidation is eliminated, thermal treatment being carried out in a vacuum or partial pressure of gas-free oxygen. Carburised layer interface with the base material is a lot more regular.
Carbon profile never shows decarburisation on the surface: no bell-shaped profile!
The carburizing depth can also be precisely controlled; results have shown a very high degree of uniformity in batches of parts and even on one part only. Moreover, the difference in enrichment depth between the side and the bottom tooth is greater than 30% after conventional carburising and oil quenching. After low pressure carburising and gas quenching it is less than 15%. This reduces the specification carburizing depth and thus the cycle time. It also helps reduce stress and toothing distortion after quenching.
There is an excellent hold to the pitting resulting from the absence of intergranular oxidation (IGO).
The ECM process makes a difference when strain or shock resistance is of importance, e.g. to increase torque in new generation gearboxes.
With perfect control of the carbon and nitrogen (if carbonitriding) enrichment, low pressure carburising contributes to increase the surface compressive stresses which favour strain resistance. On our systems, low-pressure carbonitriding® and well controlled gas quenching lead to improved mechanical properties (shock and strain).
The heat treatment does not necessarily imply that the parts will not meet the dimensional tolerances. ECM’s processes, especially gas quenching, allow a better distortion control of the parts because the cooling speed after carburising can be easily adjusted for each part shape according to specific procedures. The momentary interruption of the quenching- STEP QUENCH - is an additional tool which reduces heat stress in the material during quenching and reduces distortion.
For gas quenching, the results are very uniform, between parts and loads. Distortion is generally predictable, and its amplitude and direction more homogeneous. Therefore in some situations, they can be anticipated during processing before treatment.
- At best, the expensive final treatment is unnecessary.
- In general, the amount of material to be removed and the number of treatments are reduced.