Knowledge

HSS drills - professional tools that are tough and always up-to-date!

The machining world is full of abbreviations. We frequently read the words "HSS" and "SC", as well as the designations "HSS-E", "HSS-R" and "HSS-G". But do the tools behind these abbreviations also deliver the desired short process times during machining? Which drills are suitable for hardened steel, and which drills are best for soft materials? Here you can find out which application and material our HSS drills can be used for, as well as the occasions where a solid carbide variant may be the more appropriate, more robust solution.

There is a clear distinction between the capabilities of carbide and HSS: In the case of unstable machining conditions, small or medium batch sizes, and if toughness is the benchmark, drilling tools made from high speed steel (HSS) are used in the spindle. Our portfolio of HSS drilling tools is diverse and the same time specialised - for the best performance where it matters most. But what does HSS actually mean?

What is a HSS drill?

HSS is the abbreviation for High Speed Steel and denotes a high-alloy tool steel. HSS is therefore used for producing tools, amongst other things, because it is very easy to grind (which, for example, allows for the regrinding of worn tools). Compared to conventional tool steel or cold working tool steel, cutting speeds up to four times higher are possible, as the material can also retain its hardness at temperatures up to approx. 600°C. This is achieved through a special heat treatment during which the steel is annealed at above 1,200°C and then quenched.

Its basic structure is responsible for the hardness of the HSS, which consists primarily of iron and carbon. Alloying additions of more than 5% also come into play, whereby HSS is among the high-alloy steels.

General advantages of HSS at a glance:
  • Application temperature above 600°C
  • High breakage resistance
  • High cutting speeds possible
  • Easy to grind during production
  • Easy regrinding of blunt tools
  • Reasonably priced compared to solid carbide drills

Which HSS drill is best for which material?

The drill geometryis to a large extent responsible for the materials for which the tool is best adapted and delivers the highest performance. In the DIN manual for drills and countersinks, the division of application groups into the three N, H and W types is defined under DIN1836:

HSS drill type N:

Type N HSS drills have a "normal helix", i.e. they are traditional metal drills. These are ideal for drilling metal, iron and steel, but not soft materials.

HSS drill type H:

HSS variant H is characterised by a drawn-out helix. This drill design is suitable for machining hard, short-chipping, brittle and tough materials such as steel, hard plastic, plexiglass or laminates. 

HSS drill type W:

If you wish to machine relatively soft, long-chipping and tough materials such as soft plastics, aluminium or copper, type W HSS drills are the best choice. They have a narrow helix which also drills softer materials with precision.

Which drill for which material - three types

In the DIN manual for drills and countersinks, the division of application groups into the three N, H and W types is defined under DIN1836: 

  1. Type N: Normal helixes for materials with normal hardness such as general construction steels, non-ferrous metals and cast iron. Not suitable for soft materials
  2. Type H: Drawn-out helixes for hard, short-chipping, brittle and tough materials such as steel, hard plastic, plexiglass or laminates
  3. Type W: For soft, long-chipping and tough materials such aluminium, copper or soft plastics.

The most frequently used HSS drills at a glance

Drills made from high speed steel are produced from high quality, carefully selected steel grades. Depending on the application of the drilling tools, either conventional HSS, high alloy grades or powder-metallurgically produced steels can be used as the cutting material. Tungsten and molybdenum as alloying elements increase the wear resistance and the temper resistance of the cutting material. Cobalt also contributes to this and increases the hot hardness. Below you will find the most popular HSS drill variants.

HSS-R drills – rolled

These are all-rounders, as the rolled HSS-R drills enable the machining of steel, cast steel, grey cast iron, malleable iron, sintered iron, bronze, brass and aluminium. These drills are used most often in conventional, standard drilling work in manual and upright drilling machines. They meet basic quality requirements, remove chips well and are extremely resistant to breakage.

HSS-G drills – ground

HSS-G drills are easily distinguishable from other models, namely due to their shiny metallic, polished surface. They are produced with considerably more precision than HSS-R drills, which makes more accurate working, longer tool lives and narrow tolerances possible. What's more, they remove chips well and are self-centring. HSS-G drills are used in upright drilling machines as well as turning machines and milling centres. They machine steel, cast steel, cast iron, sintered iron, graphite, brass, aluminium and bronze.

HSS-E drills - the heat-resistant choice

The shape of HSS-E drills resembles that of the HSS-G drills. The main difference between HSS-E drills and HSS-G drills is the cobalt alloy (5% or 8%). The material in HSS-E tools is of higher quality and is at the same time extremely heat resistant, meaning that materials with high tensile strength can be machined - ideal for stainless steel. However, the cobalt alloy reduces the toughness of HSS-E drills, which makes them more prone to breakage.

HSS-E-PM drills - the special tool for high performance

Type HSS-E-PM and HSS-E drills differ in particular with regard to the production of the cutting material - this is powder-metallurgically produced for HSS-E PM drills. For this reason, this steel exhibits a finer and more even carbide distribution. They are specially designed for machining higher-alloy and higher-strength steels and materials and are characterised by high process security thanks to the uniform microstructure of the PM-HSS steel. The HSS-E-PM cutting material, combined with a coating if necessary, ensures maximum wear resistance and heat resistance at low and medium cutting speeds. The new HSS-E-PM drills fill the gap between conventional HSS drills and solid carbide drills for machining medium-strength steels or materials and medium batch sizes.

Coatings/surface treatments

The properties of HSS tools can be improved further with surface treatments or coatings. We currently offer the following variants as standard products:

  • TiN – titanium nitride coating, particularly suitable for the machining of steel and non-ferrous metals (except aluminium), maximum application temperature 450°C
  • TiAlN – titanium aluminium nitride coating, multilayer coating, maximum application temperature 900°C
  • TiCN – titanium carbon nitride coating, multilayer coating, higher cutting speed compared to TiN coating and higher wear resistance for high alloy steels in particular, maximum application temperature 450°C
  • Fibre-nitrated – increases wear protection, particularly suited to steel machining, maximum application temperature 450°C
  • Vaporised – vaporising (oxidation) reduces galling on the tool, increases surface hardness and wear resistance

For which application are HSS drills most suitable?

Are you struggling with challenging clamping conditions or the machining of thin components or sheet metal, for which there is a constant risk of deflection or vibrations in the components throughout the machining process? Then HSS tools are the ideal choice for you. These tools allow for considerably better compensation for existing loads such as transverse forces and therefore contribute to increased process security. Do you produce mostly small or medium batches? HSS drills are also ideal here, as they maintain excellent quality at a reasonable price-performance ratio.

HSS drills from CERATIZIT: the full range of HSS drilling tools

Our range of HSS drilling tools covers all user requirements: we have twist drills with diameters from 0.15 mm, centre drilling, stepped drilling and counterboring tools for virtually all materials. UNI type HSS drills are the ideal choice where the highest degree of reliability is required in production. This universal TiN coated tool with 4-faceted finish stands for low cutting forces and high stability.

Our best seller: the most popular HSS drill set from CERATIZIT

Every company has its classic products and best sellers. At CERATIZIT, the DIN 338 twist drill set always falls into this category. Available in two sets, from 1.0 mm to 5.9 mm in diameter and from 6.0 mm to 10.0 mm, these provide the user with practical dimensions with increments of 0.1 mm in the practical metal cartridge. Why is this HSS drill so popular? The affordable price and broad application range speak for themselves!

Should you buy HSS drills new or have them reground?

At some point, even the sturdy HSS drill has reached its wear limit. This begs the question: buy new or have the drill reground? After all, regrinding can usually be carried out multiple times with no issue using the CERATIZIT ReStart regrinding service for cutting tools.

Our professional regrinding service restores tools to almost their original performance capacity through the use of original geometries and coatings, so they can continue to meet all quality parameters to the highest possible standard. The process also extends the tool's life span at the same time, so new purchases make up a substantially lower proportion of your budget.

Of course, the prices of our regrinding service are also calculated fairly and transparently – with CERATIZIT's ReStart programme there are no additional charges for cutting off, roughing geometries, etc. The published prices apply irrespective of the condition your tool arrives in. If it is no longer possible to regrind your tool, it will be returned to you unmachined.

You can find further information on the regrinding service for HSS drills here

 Also see: How to prevent unnecessary wear on your drill

When is a solid carbide drill more suitable than a HSS drill?

With the growing range of materials and highly specialised machining applications, the demands on tools used are also increasing. At the latest when higher feeds or cutting speeds are required, which inevitably means that temperatures also go far beyond 600° in the machining zone, HSS drills reach their limits. However, CERATIZIT offers an extremely wide range of solid carbide tools, so the fun doesn't have to stop for machining companies.

Advantages of the solid carbide drill compared to the HSS drill:
  • Higher feed
  • Higher cutting speed
  • Shorter machining times
  • Short chips even with tough and soft materials
  • Excellent positioning accuracy
  • Good centring and guidance properties
  • Longer service lives
  • High rigidity

When you need something a little more robust: our most popular solid carbide drill

As a developer and manufacturer of high quality carbide grades and high performance cutting materials, we have also expanded our product range in terms of solid carbide drills. Type WTX solid carbide drilling tools, among others, have been a household name to users around the world for years. We also offer the appropriate WTX drill for any application and a broad selection of materials to be machined: WTX-UNI, WTX-VA, WTX-H, WTX-AI, WTX-Ti, WTX-Speed and WTX-Feed, WTX-180, WTX-Change, WTX-Feed BR. Among others, we have developed the first four-edged high feed drill, the WTX HFDS, and successfully established this on the market for cast iron and steel. Only have something small in mind? We have completed the range with our WTX-Micro for miniature holes from Ø 0.1 mm. And we have something for deep holes too: our WTX-TB deep hole drills, which can be used at up to 50xD.

If you are interested in solid carbide drills as an alternative to our HSS drills, take a look at our range of carbide drilling tools here.