Surface® Combustion pioneered the development of the Cloverleaf^TM low pressure carburizing (LPC), hardening, oil, and high-pressure gas quenching furnace design to satisfy a growing dissatisfaction with other LPC technologies. Limitations to smaller and lighter load sizes, process gases that resulted in heavy sooting, and carburizing/hardening nonuniformity all led to our unique circular hub and spoke concept combined with the use of cyclohexane. Cyclohexane is best known as camp stove cooking fuel. It comes in liquid form which allows it to be precisely metered, injected, vaporized, and then attracted to steel workpieces. Cyclohexane has a catalytic affinity for steel, and this reaction becomes the mechanism for getting carbon uniformly to the surface of the work. From this stage, typical carburizing and diffusion reactions take placed based on time, temperature, and steel composition. After LPC, the workload can be high pressure gas quenched up to 20-bar in nitrogen using high-convection cooling in a separated chamber or it can be oil quenched in a separate unique chamber. Either option is easily selectable, and the load is automatically raised and retracted from the hot zone, rotated, and placed in the respective cooling chamber. As a further advantage for those who want to do vacuum hardening, completely separate heat chambers can be used for vacuum hardening processes only. The ingenuity of the Cloverleaf design is that all chambers have vacuum tight sealed doors which allow different internal vacuum levels and process gases to be isolated from each other while all chambers are running. There is no cross-talk between any other chamber. This was a dramatic improvement over competing technology, and it revolutionized the heat treating industry with the inherent flexibility of this design.

Other features include the capability of electric heating or indirect gas firing and hot wall technology in the vacuum chambers which eliminates the conventional water jacketed designs providing operating cost savings and equipment longevity. The patented cyclohexane injection technology provides excellent load coverage of the carburizing medium. Commercial heat treaters love the system’s versatility as they never know what type of work they will be processing next.

Automation of the Cloverleaf motions and actions start when you place the load into the entry vestibule and completes when the load is withdrawn after quenching.

Learn about the energy savings