Fastener Heat Treatment Media Selection
Introduction:
Heat treatment of fasteners is an important operation used in the manufacture of fastener products. It’s purpose is to strengthen the mechanical properties, improve the anti fatigue capabilities, and enhance the fracture resistance of the material, making it suitable for use in critical applications. The process typically involves one of more thermal cycles, depending on the requirements of the application and the design of the fastener, and includes both hardening and tempering operations. Depending on the type of machinery available, different thermal cycles and heat treatment media, either solids or liquids, are available for use in the process to achieve the desired results. This paper discusses the selection of media for heat treatment operations, including quenching and tempering, as well as the various factors involved in the process.
Factors to Consider When Selecting Heat Treatment Media
When selecting heat treatment media, there are a number of factors to consider. First, the media must be able to withstand the extreme temperatures and pressures that are associated with the process. Dissipation of energy must also be sufficient, since too much energy can detrimentally affect the material and reduce its strength and ductility. In addition, the process must be controlled to ensure uniform heating and cooling of the fastener. Lastly, the media must be compatible with the fastener and must not react with the material in negative ways.
Selection of Heat Treatment Media:
Heat treatment media can be divided into two categories, solid and liquid. Solid media are typically used for hardening and include materials such as sand, metal chips, and ceramic, while liquid media are used for tempering and include air, oil, water, and nitrogen. Each type of media has advantages and disadvantages that should be taken into consideration when selecting the most suitable for a specific application.
Solid Media:
Solid media have the advantage of providing uniform heat transfer, since the same amount of heat is dispersed to every part of the material being heat treated. They are also relatively easy to control and do not react chemically with the fasteners. The main disadvantage is their inability to quickly absorb and disperse heat, which can lead to uneven heating and cooling, and can result in critical areas of the fastener being over or under-heated.
Liquid Media:
Liquid media have the advantage of being able to absorb and dissipate heat quickly and efficiently. However, they do require more precise control, as temperatures can easily be exceeded. In addition, some liquids, such as oil and water, can chemically react with the material, resulting in adverse affects.
Conclusion
The selection of heat treatment media is an important aspect in the manufacture of fasteners. Depending on the application and the machinery available, the most suitable media can be selected. Solid media are typically used for hardening operations, while liquid media are used for tempering. Consideration must be given to their ability to withstand extreme temperatures and pressures, as well as their ability to dissipate energy, while avoiding chemical reaction with the fastener.
In conclusion, the selection of the correct media for fastener heat treatment can greatly impact the quality and reliability of the finished product. Knowing the various factors that affect the media’s performance, such as temperature and chemical compatibility, can help in making the best choice for the given application.
