Hardening of Machine Tool Guide Ways

Machine tool guide ways are hardened to increase their wear resistance and improve their durability. Hardening is a heat treatment process that involves heating the material to a specific temperature and then rapidly cooling it to increase its hardness. There are various methods of hardening, including induction hardening, flame hardening, martempering, and others.

1. Induction Hardening:
Induction hardening is a surface hardening process in which the guide ways are heated using an induction coil. The high-frequency alternating current induces a current in the guide ways, causing them to heat up. Once the desired temperature is reached, the guide ways are quenched to cool them rapidly, resulting in a hardened surface. Induction hardening is commonly used for hardening machine tool guide ways due to its ability to provide localized hardening and precise control over the hardened depth.

2. Flame Hardening:
Flame hardening is another method used for hardening machine tool guide ways. In this process, a flame is directed onto the surface of the guide ways using a torch. The heat from the flame rapidly heats up the surface, and then the guide ways are quenched to achieve the desired hardness. Flame hardening is suitable for large and complex-shaped components and is known for its flexibility and cost-effectiveness.

3. Martempering:
Martempering, also known as marquenching, is a process that involves quenching the guide ways in a bath of molten salt or oil. Unlike conventional quenching, martempering provides a more uniform and controlled cooling rate, resulting in reduced distortion and cracking. The guide ways are heated to the austenitizing temperature and then quickly transferred to the quenching medium for a specific duration. Martempering is commonly used for medium to large-sized machine tool guide ways.

Conclusion:
Among the options provided, the correct answer is option 'B', flame hardening. Flame hardening is a widely used method for hardening machine tool guide ways due to its flexibility, cost-effectiveness, and suitability for complex-shaped components. It involves heating the guide ways using a torch flame and then quenching them to achieve the desired hardness.