What is HSS Drill Bit? – I Found These!


Drill bits are made with different materials. In order to drill high strength and hard material drilling process, steel drill bits are used to drill wood. But drilling steel and more hard material will need more hard drill bits. As a solution of this high-speed steel (HSS), drill bits are made. Let’s see what is HSS Drill bit?

HSS drill bits are made by mixing these materials 0.85% C; 4% Cr; 5% Mo; 6% W; 2% V. According to its material mixing proportion, strength has varied. M1, M2, M7, M35, M42, and M50 have different strengths and resistance HSS. HSS is used for drill bits, cutting tools, knife and many tough tools.

When you use the HSS drill bit you should know its material properties, how to use it?, where to use and many more details. So you can grab all in detail by using the below article. So keep reading on until you find your information.

Related Topic

How HSS Drill Bit is Made?

What is HSS drill bit
HSS Drill Bits

HSS drill bits are made with 0.85% C; 4% Cr; 5% Mo; 6% W; 2% V (M2). The main material is steel. By changing these material proportions, its hardness can be varied. M1, M2, M7, M35, M50, M42 are the strength class of the HSS. Drill bits are made with mostly M2.

TypeCarbon
(%)
Tungsten
(%)
Molybdenum
(%)
Chromium
(%)
Vanadium
(%)
Cobalt
(%)
Hardness
Rockwell C (%)
Term
M10.801.508.004.001.0063-65“HSS”
M20.856.005.004.001.9063-65“HSS”
M71.001.758.754.002.0063-65“HSS”
M350.806.005.004.002.00565-675% Cobalt
M421.101.509.503.751.15865-67Super Cobalt
M500.850.104.254.001.0063-65“HSS”
High-Speed Steel (HSS) types and Mixed Material
TypeUsage
M1Use for general purpose
M2Twist drills, reamers, milling cutters, taps, and dies, broaches, knives, saws, cold work tools
M7Heavy construction equipment
M35Use for fast cutting and durable cutting tools
M42Use for higher cutting speed tools
M50Use for drill bits, ball bearings
Types of High-Speed Steel (HSS) and its usage

Properties of High Speed Steel

Density (×1000 kg/m3) – 8.67
Poisson’s Ratio – 0.27-0.30
Elastic Modulus (GPa) – 190-210
Thermal Expansion (10-6/ºC) – 9.7 
Thermal Conductivity (W/m-K) – 19.9 
Rockwell Hardness – 63-65

The high-Speed Steel drill bit can only drill 2-3 times the drill diameter before pecking. This means when you drill once, you can drill 2-3 times the drill diameter into the material without tool coolant. You have to pull out and then drill again.

Read More About – How to Identify the Drill Bits? – Expert Guide!

Compared With Other Types of Drill Bits

Steel Drill Bits
HSS drill bits are more strong and hard than steel drill bits. Steel drill bits are used to drill the softwood and some plastics. Steel Drill bits can be overheating when it uses for tough material drilling such as cast iron, concrete, stone, etc.

Cobalt Drill Bits
HSS is less strong than the cobalt drill bits. Cobalt Drill bits are different from HSS with the mixed cobalt percentage. When the cobalt is added 5%, it is called 5% cobalt, and 8% is called super cobalt. These tools are really hard, strong, and heat resistant than regular HSS. So Cobalt drill bits can be run faster and high-speed feeds.

Carbide Drill Bits
Carbide drill bits are more strong than HSS drill bits. Using a carbide drill bit, you can drill more fast and high RPM. Although HSS is coated with some materials, its hardness can’t be compared with the carbide drill bits. It is higher than HSS.

Diamond Drill Bits
Extremely strength than HSS. Diamond drill bits are used for the drilling and cutting of extremely hard materials such as tile, glass, and stone, etc. HSS is not able used instead of these.

How to Sharpen the HSS Drill Bit?

You can sharpen the HSS drill bit when the chipping length is below 0.02,” or drilled holes are out of the tolerance. When the drilling produces more noise is another sign of sharpening. You can use a file or grinder made with carbide or diamond. The cutting angle should maintain according to the material requirement.

Workpiece MaterialPoint AngleHelix AngleLip Relief Angle
Aluminum90 to 13532 to 4812 to 26
Brass90 to 1180 to 2012 to 26
Cast iron90 to 11824 to 327 to 20
Mild Steel118 to 13524 to 327 to 24
Stainless Steel118 to 13524 to 327 to 24
Plastics60 to 900 to 2012 to 26
Drilling angle and workpiece material Source

Read More About – 26 Types Drill Bits for – Metal | Wood | Stone | Concrete

Usage and Cutting Speed?

HSS drill bits are used to drill mild steel, cast iron, softwood, plastic, hardwood, fiber, and many soft materials. You can use a 118-degree angle for soft material drilling such as aluminum, softwood etc. And 135-degree for the hard material drilling such as cast iron using the HSS drill bits.

MaterialRecommended speed (SFM)
Aluminum and its Alloys200-300
Brass and Bronze (Ordinary)150-300
Bronze (High Tensile)70-150
Die Casting (Zinc Base)300-400
Iron-Cast (Soft)
   Cast (Medium Hard)
   Hard Chilled
   Malleable
75-125
50-100
10-20
80-90
Magnesium and its Alloys250-400
Monel Metal or High-Nickel Steel, Stainless Steel30-50
Plastics or Similar Materials100-300
Steel
 Mild .2 Carbon to .3 Carbon
 Steel .4 Carbon to .5 Carbon
 Tool 1.2 Carbon
 Forgings
 Alloy – 300 to 400 Brinell

80-110
70-80
50-60
40-50
20-30
Cutting Speed of HSS (high-speed steel) Source

You can calculate RPM using the SFM as below,

R.P.M. = (3.8197 / Drill Diameter) x S.F.M.

Read More About – How to Drill Cast Iron? – The Detailed Guide

Conclusion

HSS drill bits are more strong than steel drill bits. Its hardness, strength, resistance can be varied as below

Steel drill bits < HSS drill bits < Cobalt drill bits < Carbide drill Bits < Diamond drill bits

It can be used for many reasons. Moslty HSS drill bits are used to drill steel.

Tom Mackenzy

I am Tom, I am really interested in DIY projects. I have my own workshop and I spend my free time with so many projects. So I would like to share my experience with you regarding power tools, woodworking, metalworking, etc.

Recent Posts