How to Choose the Right Twist Drill Bit

October 28, 2021

How to Choose the Right Twist Drill Bit

Drill bits are commonly used in the fabrication industry for boring holes in hard metal surfaces, wood, or other material. It is a versatile tool, the most helpful and flexible tool that exists. Although using the wrong tool not concerning the application can damage either the product or the tool. Various Drill Bits are available, including the cobalt drill bit, carbide drill bits, titanium drill bits, HSS drill bit, twist drill bits etc.

What is a Twist Drill Bit? 

Twist drills, also known as bend bits, are the most broadly utilized out of all drill bit types. These drill bits can cut anything from wood and plastic to hard steel and cement and are the best drill bits for stainless steel, so they are by and large produced using M2 high-velocity steel. At measurements up to around 1/2", twist drills are not just the least expensive of all pieces a carpenter could utilize; they offer the amplest choice of sizes. Even though it is a drill bit for metal, it also functions perfectly for sharp wood cutting. This, by and large, implies that they have not been utilized to cut hard materials like steel. 

How to Select the Right Twist Drill Bit?

A twist drill bit is a metal bar of a particular diameter with two, three, or four spiral flutes. 

  • Two spiral flutes are intended for essential penetrating.
  • Three-and four-woodwind drills are just for expanding already bored holes when required.

The segment part between the two spiral flutes is known as the web, and a point is shaped by inclining the web to the point of 59° from the drill's axis, which is 118° comprehensive. This structures an inclined cutting edge at the edge of the flute, which is known as the lip. A twist drill gives low- efficiency at a certain point when the web leaves a narrow space for swarf or debris and because the point has a low surface speed contrasted with the fringe. Consequently, a decent plan for drilling bigger openings is to initially penetrate 1/4" or less and afterward follow with the drill of the ideal distance across.

When selecting the twist drill bit for your application, always ensure that it has the following Eight basic features to match high efficiency and better performance.

Point Angle

The point is situated on the top of the twist drill bit. The point is estimated between the two fundamental cutting edges at the top. A point is an important feature of a twist drill bit to focus on the material while drilling or cutting. The smaller point allows better focusing on the material. This additionally diminishes the danger of slipping on bent surfaces. 

The bigger the point, the more limited the tapping time. In any case, the higher contact pressure is required, and focusing on the material is harder. 

Cutting Edge

The cutting edge controls the main cutting process control. Regardless of whether the distinctions are tiny, long cutting edges have a higher slicing execution contrasted with short front lines. The twist drill consistently has two fundamental forefronts associated with a cut chisel edge.

Cutting Chisel Edge

The cutting chisel edge is situated in the drill tip and has no cutting impact. Notwithstanding, it is fundamental for developing the contort drill, as it interfaces the two primary cutting edges. 

It is liable for entering the material and applying tension and erosion to the material—these properties are negative for the drilling system and expanded force utilization. 

Point Cuts & Point Thinning

The point thinning lessens the cutting edge at the highest point of the twist drill. The thinning of the point outcomes in a significant decrease of the grating powers in the material and consequently a decrease of the vital feed power. This implies that point thinning is the conclusive factor for focusing on the material. It works on the tapping. 

The different point thinnings are normalized in DIN 1412 shapes. The most widely recognized shapes are the helical point (shape N) and split point (shape C).

Spiral Flute Profile (Groove Profile)

Because of its capacity as a channel framework, the profile of the spiral flute advances chip retention and evacuation—the more extensive the groove profile, the better the chip ingestion and expulsion.  

Wide notch profiles are level; dainty section profiles are profound. The profundity of the notch profile decides the thickness of the drill center. Level furrow profiles permit enormous (thick) center widths. Profound furrow profiles permit little (slight) center widths. 

The Core of the Drill Bit

The core or center thickness is the deciding measure for the reliability of the twist drill. Twist drill bits with a thick core distance have higher dependability and are appropriate for harder materials. They are likewise very appropriate for handheld drills as they are more impervious to vibrations and horizontal powers.

Secondary Cutting Edge and Guiding Chamfers

The two guiding chamfers are situated at the spiral flutes. The pointedly ground chamfers works on the side surfaces of the borehole and back the direction of the bend drill in the drilling. The nature of the borehole walls likewise relies upon the properties of guiding chamfers. 

The secondary cutting edge frames the progress from guide chamfers to groove profile. It releases and cuts chips that have adhered to the material. The length of the aide chamfers and secondary cutting edge generally rely upon the helix point. 

Helix or Spiral Angle

A fundamental component of a twist drill is the helix point (twisting point). It decides the process of chip arrangement. Bigger helix angles give potent removal of delicate, long-chipping materials. Smaller helix points are utilized to remove hard, short-chipping materials.

Turn penetrates with a tiny helix point (10° - 19°) have an extensive spiral. Consequently, bend drills with a huge helix point (27° - 45°) has a slammed (short) twisting. Bend drills with a typical twisting have a helix point of 19° - 40°.




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