With the many advances that have taken place to improve quality in the gear industry, it is only logical that heat treat services would have to change to meet the increased demands of precision gear manufacturers. For decades, gear manufacturers used atmosphere batch furnaces with integral oil quenches for the case hardening process. In recent years, low pressure carburizing (LPC) and high pressure gas quenching (HPGQ) have become a preferred technology for fuel injection components and transmissions.
LPC Advantages
Low Pressure Carburizing is a case hardening process that is performed in a pressure of only a few millibar in a protective atmosphere. In most applications acetylene is used as the carbon source. The advantages of LPC compared to conventional gas carburizing are:
* No intergranular oxidation
* No surface decarburization
* Faster carburizing
* Higher carburizing temperature
* Significantly shorter cycle times
HPGQ Benefits
LPC is usually combined with the HPGQ process, during which the load is quenched using an inert gas-stream instead of a liquid quenching media. Nitrogen or helium are usually used as quench gas. The benefits of HPGQ compared with liquid quench are numerous, including:
* Reduced distortion in most applications
* Clean surfaces after heat treatment
* Environmentally friendly, with no post washing of parts required
* Heat treatment can be integrated into the production line
Outsourcing Benefits
A manufacturer must decide whether to outsource the heat treatment to a service provider or to perform in-house heat treatment. The following outsourcing benefits should be considered:
* No investment in heat treatment equipment and the required infrastructure
* No additional staff to conduct heat treatment operations, laboratory, or maintenance
* Access to the latest state-of-the-art heat treatment technologies without expenditures for development
* A certified quality control program tailored to meet customer requirements
* Heat treatment costs are predictable and at a fixed price
Outsourcing Disadvantages
However, the disadvantages of outsourcing of heat treatment are:
* The in-house production competence of the manufacturer will be partly reduced
* The heat treatment process will not be integrated into the production line of the manufacturer
* Possible transportation costs and increased inventory management requirements
* External interface to heat treatment, therefore possible higher costs resulting from communication and documentation.
