Drill bits are a common type of cutting tool used to create holes with a circular cross-section from the objects through removing excess materials, come in different drill bits sizes for various needs. What are drill bits made of? In this article, let’s explore the different types of drill bit materials.
Drill Bit Material Types & Coating - Types of Drill Bits
1. Carbon Steel Drill Bit
– Low carbon steel: this is the cheapest option for making a drill bit, due to their poor tempers, low carbon steel drill bits are usually used for drilling softwood and some plastics, and require to be sharpened often to extend the lifespan.
– High carbon steel: a better material than low carbon steel, high carbon steel drill bit can keep their shape and effectiveness longer, so it can be used to cut stronger materials, like hardwood and soft metals.
2. High Speed Steel Drill Bit
Compared with carbon steel bits, high-speed steel drill bit is a more popular choice on the market now. HSS is a special type of carbon steel, maintaining structural integrity while bearing high temperature is a marking advantage of the HSS drill bit, what’s more, high speed steel bit has higher wear resistance and hardness, it can also work well at a normal temperature. HSS drill bits are suitable for most of the wood and metal drilling process, including CNC drilling. Titanium nitride and other types of coatings can be applied on the HSS tool to increase lubricity and reduce friction.
3. Titanium Coated Drill Bit
Titanium is not only a popular aerospace and medical material, but also a versatile drill bit coating material, which can make the drill bit last longer. Due to its high corrosion resistance, good fatigue limit, heat limit, relatively light weight, and longer service life, titanium coated drill bit is perfect for repetitive mass production of drilling into steel, iron, wood, plastic and various surfaces, it allows a faster RPM and shorter cycle time. The most common types of titanium coatings are Titanium Nitride (TiN), Titanium Aluminum Nitride (TiAN) and Titanium Carbon Nitride (TiCN). TiAN and TiCN are considered superior to TiN as they can increase the lifespan to a considerable degree. The drawback of drill bit coating is that once the tooling becomes blunt, it can’t be sharpened to avoid the coating material being worn away.
4. Cobalt Drill Bit
Cobalt is another type of coating for the drill, cobalt drill bit is used for cutting materials that HSS bit can’t, such as stainless steel and other difficult materials, it can retain hardness at much higher temperatures than HSS and not affected by extremely high heat. But cobalt is a too brittle coating.
5. Carbide-Tipped Drill Bit
Carbide-Tipped drill bit is very hard, easy to dissipate heat and can hold an edge longer than other type bits. Similar to the cobalt drill bit, it’s very brittle as well and maybe broken up in improper use. Carbide bits are applicable for drilling fiberglass reinforced plastic and nonferrous heavy metals.
6. Diamond Drill Bit
Polycrystalline diamond (PCD) is one of the hardest drill bit material, which can be used on the toughest materials, such as glass and ceramic. Actually, diamond tool generally used to grind away material on a micro level, it can last up 20 times as long as a bare tungsten carbide tool, but it also cost much higher than any other options. And diamond bits react negatively when work with ferrous materials like hot steel.
Drill Bit Material Comparison - What is Best Drill Bit Material?
The material is a major factor for the drill bit selection, because it also affects the price, properties and service life. Are you wondering what is the best drill bit material for metal, wood, titanium, or steel? Here we’ll compare some materials.
1. Cobalt vs Carbide, which drill bit to choose?
– Price: cobalt drill bits are cheaper than carbide bits.
– Properties: carbide bits can resist more temperature than cobalt and HSS.
– Cutting speed: carbide > cobalt
– Application: cobalt bit can drill stainless and hardened steel, carbide bits are widely used for drilling nonferrous heavy metals, cast iron and abrasive materials.
2. Cobalt vs Titanium, which drill bit is better?
– Composition: titanium bits are made of carbon steel or high speed steel with TiN, TiAN or TiCN coating, cobalt bits are HSS bits with cobalt in alloy.
– Application: titanium coated drill bits can make the tool last longer and reduce temperature when cutting plastic and wood, the cobalt bits are intended for stainless steel and hardened alloy steel.