Surface^® Combustion took the multi-chamber concept and perfected it by offering true vacuum tight sealing between the heating chamber and the quenching chamber. This is the heart of our design and what makes it work so well. A machined, vacuum-tight, inner door separates the chambers and provides true vacuum, partial pressure, or low-pressure vacuum carburizing processes to work independently and uninhibited from the gas quenching or oil quenching cooling chamber. No oil vapors cause process degradation or work load discoloration. The workloads are transferred between the different chambers using two styles of mechanisms. Normal sized loads use a telescoping carriage fork mechanism to move the load to and from the heating chamber. Heavier loads used a rack and pinion driven graphite carriage mechanism. Both transfer mechanisms are reliable and proven over time. The gas quenching option also provides for the added benefit of transferring a hot load into a cold chamber where it is backfilled and cooled via a high-capacity, recirculating fan directing the hot wind through water-cooled finned cooling coils. The horizontal vacuum chambers are typically water jacketed, but options are available to eliminate some or all the water cooling in this area. The operating temperature range is typically from 1400°F to 2400°F.

Heating is performed under a vacuum, the level of which is determined by the pumping system selected. For vacuum levels down to 10 microns, a combination mechanical piston pump with a blower is used. If higher vacuum levels are required, a diffusion pumping system operating in conjunction with the base pumping systems would be used.

The inner chamber is typically graphite-based rigid board and/or felt with machined graphite resistance heating elements. All are mounted within a stainless steel inner chamber frame which allows for multiple rebuilds within the same frame. The heating elements are powered with a low-voltage, high-current variable reactance transformer.

Oil quenching is accomplished in a shrouded and agitated oil bath to uniformly direct and distribute the oil up through the workload for optimized quenching and minimized distortion. The oil can be heated via electric bayonet style heating elements and likewise is cooled after quenching to return the oil temperature to the setpoint.