Making Cobalt and HSS Tools for Precision and Durability
Cobalt and high speed steel (HSS) cutting tools have to perform consistently and quickly for some of the most tough-to-machine applications. They can operate at faster speeds and higher feed rates because they retain a high red hardness that gives them higher heat resistance.
That hardness is forged during the metallurgical process. Consequently, this process is a critical phase in cobalt and HSS tool manufacturing, so it may be helpful to understand what cobalt and HSS cutting tools go through and what Regal does to ensure precision machining over a longer life cycle.
Properties of High Speed Steel
High speed steel provides high hardness at temperatures up to 1000°F, and high wear resistance from alloying elements like tungsten, molybdenum, vanadium and chromium, which are able to form carbides. Cobalt may be added to improve hardness.
HSS tools have a precise cutting ability because of a combination of properties, the four most important of these being:
- Hardness – resistance to penetration by diamond-hard indenter, measured at room temperature
- Hot hardness – the ability to retain high hardness at elevated temperatures
- Wear resistance – resistance to abrasion, often measured by grindability, metal-to-metal, or various other types of tests
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Toughness – ability to absorb (impact) energy
Heat Treatment for Cobalt and High Speed Steel Tools
The heat treatment process can be divided into four primary areas: preheating, austenitizing, quenching, and tempering.
Regal’s heat process looks like this:
- Heat to 2205º F to harden in vacuum usually takes 5 minutes
- Quench from 2205º to 1600º in one minute with special controls
- Cool to 150º in vacuum for handling then stress relieve temper in three stages to 1070º
Quality Control is Critical
Machinists expect a high level of precision and durability in their HSS and Cobalt cutting tools so it's important for Regal Cutting Tools to ensure proper heating control practices are in place before shipping these products.
It starts with tight controls in our metallurgical process, where we employ an environmentally friendly IPSEN vacuum furnace that ensures uniform temperature distribution and creates no residual waste like other systems do. The furnace is monitored automatically to enable consistent operation during each cycle.
Prior to shipment, each lot of steel is previewed to ensure compliance to our stringent QC requirements. We record the details of each load, relative to size and quantity, and a random sample from each load is measured to record conformance to our hardness specifications.
Finally, we retain all cycle records in case there is a question about the hardness of a specific tool. That tool can be traced to a heat treat lot by the date code etched on the tool.
Want to see how these Regal Cobalt and HSS tools will improve your process? Test one of these tools in your facility today!