Low Pressure Carburizing (LPC) or Vacuum-based Carburizing
In vacuum carburizing, propane or acetylene are usually selected for all carburizing processes without any specific geometrical requirements. However, it has been proven that acetylene offers better carbon efficiency compared to propane because of its instability and higher carbon content per mol of gas. Therefore, by using acetylene, densely packed loads, especially parts with complicated shapes can be carburized at high, reproducible quality.

Small quantities of carburizing gas are introduced in the hot zone and are drawn-off by the vacuum pumps. Process parameters like temperature and gas flow are selected according to the parts requirements and are used for the process control. To achieve the specified carbon profile, the carburizing is done in alternating steps for carburizing and diffusion, followed by a final diffusionstep. These sequences are also parameters for the process control.

Process Advantages
Compared to the processes using atmospheric conditions, vacuum carburizing has a lot of advantages. Due to a higher carbon mass-flow rate, the cycle time is considerably reduced. Vacuum furnaces easily allow higher temperatures, thus process times can be reduced dramatically, especially for bigger case depths.
Because of the absence of oxygen (air), the quality and properties of the parts surfaces are improved.

High Pressure Gas Quenching (HPGQ)
For many years now, gas quenching has been the preferred process in the heat treatment of high-speed steels and hot and cold working tool steels.
With the development of separate gas quenching chambers, it is often possible to replace oil quenching with high-pressure gas quenching using nitrogen or helium for heat treating case hardening steels or other low alloyed materials.

Process Advantages
The main advantages of high pressure gas quenching are reduced distortion which mostly helps to avoid hard machining steps and dry and clean parts afterwards. After gas quenching the parts surface is free from quenching media, dust or other residuals, which is the required condition for further process steps like coating.

Equipments
The technology of LPC plus HPGQ had been developed for industrial applications already more than 10 years. The equipment and system have been also accepted by the thermal processing industry all round the world. Transmission and injection system are two of the biggest market segments currently. In order to cater for these automotive mass productions, modular systems become mature to expand the capacity flexibly along the volume ramp-up. Each modular capacity could support the load as large as 900mm(w) x 1800mm(l) x 900mm (h).