According to industry sources, the global market for high speed steel (HSS) cutting tools is expected to grow to more than $10 billion by 2020. Jackie Wang-General Manager of Shanghai Histar Metal, looks at why HSS remains a popular option, the different compositions available and how the material has adapted to a fast-changing industry.

Despite the growing competition from solid carbide, HSS continues to be popular with manufacturers due to its high wear resistance and excellent hardness and toughness properties. HSS cutting tools are best suited to mass production environments where tool life, versatility, productivity and tool cost are of the highest importance to an end-user. It therefore still play a major part in efficient and reliable machining of many components.

Also, the current focus for a good product quality, which meets the customer application requirements at a cost-effective price, is proving attractive in the present global economic climate.

To support the growing worldwide demand for HSS, cutting tool manufacturers have committed extensive resources to this segment. This includes increased investment in not just new product development but also research and development activities, which has led to HSS tools becoming more reliable with a reduction in the number of defects, lower production costs and shorter lead-times. The addition of improved substrates, including powder metallurgy and coatings have been instrumental in further enhancing performance.

Shanghai Histar Metal provides high speed sheet, round bar and flat bar. These materials are used for drills, countersinks, reamers, taps and milling cutters.

HSS composition

A typical HSS composition features chromium (4%), tungsten (approx. 6%), molybdenum (up to 10%), vanadium (around 2%), cobalt (up to 9%) and carbon (1%). The different grade types depend on the varying levels of elements added.

Chromium improves harden ability and prevents scaling. Tungsten offers greater cutting efficiency and resistance to tempering, as well as improved hardness and high temperature strength. Molybdenum – a by-product of copper and tungsten production – also improves cutting efficiency and hardness, as well as resistance to tempering. Vanadium, which is present in many minerals, forms very hard carbides for good abrasive wear resistance, increases high temperature wear resistance and strength, as well as retention of hardness.

Cobalt improves heat resistance, retention of hardness and slightly improves heat conductivity, while carbon, increases wear resistance and is responsible for the basic hardness (approximately 62-65 Rc). The addition of 5-8% more cobalt to HSS improves strength and wear resistance. Typically, drills made with the addition of more cobalt are used in application specific operations.

Advantages

HSS tools can resist vibrations, whatever the type of machine tool, even if rigidity has been lost over time and regardless of work piece clamping conditions. It can prevent mechanical shocks at tooth level in milling operations and cope with varying lubrication conditions which may result in thermal changes.

Also, thanks to the inherent strength of HSS, tool manufacturers can produce extremely sharp cutting edges. This make it easier to machine difficult materials, offers less work hardening of austenitic stainless steels and nickel alloys, and gives a better surface quality and tolerances of machined parts.

As the metal is cut and not torn, it provides longer tool life with lower cutting-edge temperatures. It also requires lower cutting forces, which ultimately means less power consumption from the machine tool. From a tool life point of view, HSS performs very well with intermittent cutting applications.

Summary

In an age where users require reliable, consistent, versatile tools at a cost-effective price, high speed steel is still the ideal choice for many applications. As such, it can still hold its own in the marketplace against younger and more technically advanced materials.

If anything, HSS has over many years become stronger by adapting itself with new coatings, adjusting its composition and adding new technology, all helping to retain its position as a vital material in the metal cutting industry.

The cutting tool sector industry has always been a competitive landscape and HSS remains a key component to offering customers what has always been an essential requirement: good choice.

Shanghai Histar Metal

www.yshistar.com