Drill bits are cutting tools which are used to make holes. Different kind of material need different types of drill bits depending on strength and hole cross section. Drill bits are attached to chuck of drilling machine and with rotation, it remove material to create holes in that material.
You may have doubt that Does selection of drilling bits makes any difference, considering primary function is to drill anyway? Using a wrong drill bits not only can hinder production, but also could be more costly.
#1 Drill bits types
Drill bits are made of different type of material depending on its usages. Following are different type of drill bits material
Carbon Steel are mainly used only for drilling wood or a few soft metals. It gets overheated due to frictional heating while drilling, they may lose their temper, resulting in a soft cutting edge. carbon steel drill bits do not hold an edge well and require frequent sharpening.
High-Speed Steel (HSS) is a popular material of making drill bits which are to be used for drilling into soft steels as well as wood and plastic. HSS drill bits are hard and resistant to heat.
High Steel Cobalt (HSCO) is high-speed steel that contain more cobalt. Infusion of 5-8% of cobalt gives upgrade from HSS strength. Which makes HSCO a great option for drilling into harder steel as well as stainless steel grades. In addition to strength more proportion of cobalt makes HSCO more brittle than HSS, so these required to be placed at proper angle to avoid breaking of bits while drilling.
Carbide (Carb) drill is used majorly for production drilling where a high-quality tool holder and equipment is used. It is not used in hand drilling machine because of its brittle nature which is highest among all material drill bits type. These drill bits are designed for the most demanding and hardest materials.
#2 Drill Bit Coatings
Black Oxide coating over drill bits helps reduce friction and increase chip flow. It is an inexpensive coating that also provides heat resistance and lubricity along with protection against corrosion. Suitable for Ferrous materials.
Titanium Nitride or TiN (gold color) is very hard ceramic material used in coating of high-speed(HSS) drill bit. It extends the drill life by at least 3 times. Even if you sharpen drill bits, the coating provides an increased tool life.
Titanium Aluminium Nitride or TiALN (violet color) is similar to TiN but with higher efficiency. Makes drill bits increases life by 5 times or more. Used in high-alloy carbon steels, nickel-based materials, and titanium. Not suitable for Aluminium based tool coating.
Titanium Carbon Nitride or TiCN (blue-gray color) is superior coating to TiN. Used for stainless steel, cast iron, and aluminium. It is harder and more wear-resistant than other coatings. You can identify this coating by blue-gray over drill points.
Diamond coating is often used for cutting tile, stone, and other very hard materials.
#3 Drill bits angle
90° Aggressive angle– This 90 degree drill bits angle is suited for very soft material such plastics and other such. Not used with hard materials. These bits are self-starting and can cut very quickly.
118° Standard angle — Found on most common drill types. Used for drilling in wood, metal, plastic, and most other materials.
135° Self-Centering angle — This type will begin drilling faster, especially in stainless steel materials
150° Shallower angle — This 150 degree drill bits angle is suitable for drilling steels and other tougher materials. Drill bits of this angle requires a starter hole for drilling further.
Drill bits with no point angle are used where a blind, flat-bottomed hole is required. In-spite of all these variation most common angles for drills are 118° and 135°.
#4 Drill bits for wood
Twist Drill bits are the most common drill bits used in drilling woods, metal and plastic. They are made from High-Speed Steel or Carbon Steel.
Aparna 1.5-6.5 mm HSS High-speed Steel Drill Bit for wood
- 13 pcs HSS High-speed Steel Drill Bit
- Drill Size 1.5-6.5mm
- Suitable for woods and light metals
#5 Drill bits for concrete
Bosch 2608590090 Masonry Drill Bit Set for concrete
- Size Diameter: 4mm, 5mm, 6mm, 8mm and 10mm
- Material: HSS with brazed carbide tip
- Used with impact or hammer drill machines.
- To be fitted with keyed or keyless 3 way jaw chuck.
#6 Drill bits for metal
Metal Drill Bits are made for faster drilling on all metal surfaces except for aluminium. The bits are fine for DIY-shed-bloke to use occasionally for light to medium jobs.
Bosch HSS-R Metal Drill Bit for metal
- 10 twist drill bits made of high speed steel
- 1-10 mm size
- Low risk of breakage thanks to excellent elasticity
Drill bits are often used with drilling hammer where it function along with chuck. Using proper drilling machine and drill bits result in excellent work finish otherwise you will end up damaging drill bits and material both.
You may look for best drilling machine
Happy Drilling !!