What are the materials used for drilling bits?

Feb 19, 2023

What are the materials used for drilling bits?

The drilling operation is essentially a cutting process, and the prerequisite for completing the cutting process: the hardness of the tool material must be higher than the hardness of the processed material.

The materials of drill bits are generally divided into HSS, HSS with cobalt, powder HSS, and tungsten steel drill bits. The hardness of the above-mentioned drill bit materials gradually increases, and under normal circumstances, the drill bit cannot drill the workpiece or wear, the hardness of the drill bit and the hardness of the workpiece can be converted into HV Wechsler hardness, if the hardness of the drill bit is more than 3 times the hardness of the workpiece, the higher the surface hardness of the drill bit, the better and the longer the life of the drill bit.

Introduction to the characteristics and uses of various types of drill bits

Twist Drill

The twist drill is the most widely used hole-processing tool. The usual diameter range is from 0.25 to 80 mm. It consists mainly of the working part of the drill and the shank. The working part has two spiral grooves, resembling a twist, hence the name. In order to reduce the friction between the guiding part and the hole wall when drilling, the twist drill gradually decreases its diameter in the direction of the shank from the drill tip to the inverted cone shape. The spiral angle of the twist drill mainly affects the size of the cutting edge, the strength of the flap and the chip removal performance, which is usually 25° to 32°.

In order to improve the cutting performance of the twist drill, the cutting part can be resharpened into various shapes according to the nature of the material to be processed. There are two types of twist drills: straight shank and tapered shank. The former is clamped in the drill chuck while the latter is inserted in the tapered hole of the machine tool spindle or tailstock. General twist drills are made of high-speed steel. The twist drill with welded carbide insert or crown is suitable for processing cast iron, hardened steel and non-metallic materials, etc. The integral carbide small twist drill is used for processing instrument parts and printed circuit boards, etc.

Flat Drill

The cutting part of the flat drill is spade-shaped, with a simple structure, low manufacturing cost and easy introduction of cutting fluid into the hole, but the cutting and chip removal performance is poor. There are two types of flat drills: integral type and assembled type. The integral type is mainly used for drilling micro-hole of 0.03~0.5mm in diameter. The assembled flat drill with interchangeable inserts and internal cooling is mainly used for drilling large holes with diameters of 25 to 500 mm.

Deep hole drilling

Deep hole drilling is usually a tool for processing holes with a ratio of hole depth to hole diameter greater than 6. Commonly used are gun drills, BTA deep hole drills, jet drills, DF deep hole drills, etc. The nesting drill is also commonly used for deep-hole machining.

Reaming Drill

Reaming drills have 3-4 teeth and are more rigid than twist drills. They are used to enlarge existing holes and improve machining accuracy and finish.

Countersinks

A countersink is a cutting tool that makes a conical hole in an object. A common use is to make the head of a countersunk bolt or screw, when placed in the hole, flush with or below the surface. Countersinks can also be used to remove burrs left behind during drilling or tapping operations.

Countersinks have more teeth and are used to shape the end of a hole to the desired shape. They are used to machine countersunk holes for various countersunk screws or to flatten the outer face of a hole.

Center Drill

The center drill is used for drilling the center hole of shaft workpieces. It is essentially a combination of a twist drill with a small spiral angle and a countersink, so it is also called a composite center drill.

Application scenarios for different materials drilling bits

For drilling holes in wood materials, woodworking drill bits are used. Woodworking drill bits for cutting sales are large, tool hardness requirements are not high, and the tool material is generally high-speed steel (HSS) in general.

Drilling in general metal materials (alloy steel, non-alloy steel, cast iron, cast steel, non-ferrous metals), drilling materials are generally high-speed steel (advanced tools containing cobalt elements HSS-Co).

Drilling in concrete materials and stone materials, using percussion drills with masonry bits, with a bit material generally hard alloy.

Tile drill bits are used for drilling holes in hard tiles and glass. The tool material is tungsten-carbon alloy. Due to the high hardness and poor toughness of the tool, attention needs to be paid to low speed without impact.

A drill bit is a tool used to drill or blind holes in physical materials and to extend existing holes. Commonly used drills mainly include twist drills, flat drills, center drills, deep hole drills, and socket drills. Although reamers and hole drills cannot drill holes in physical materials, they are usually classified as drill bits.

High quality drilling bits supplier

BESTWIN Tools Co.,Ltd. is a professional hand tool and accessory supplier of high-quality, effective, and reliable drills, hole saws, pneumatic tools, and other tool components worldwide. BESTWIN offers the hardest and most durable drill bits. Suitable for any working conditions and needs. You are welcome to contact BESTWIN anytime to get the latest price quote.

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