The Manufacturing Process of a Fully Ground Taper Rock Mining Button Drill Bit

A fully ground Taper Drill Bit outperforms milled alternatives because the entire geometry—flutes, lands, and Morse taper—is finished on a 5‑axis CNC grinder. This technical article walks through the complete workflow: Cutting HSS or cobalt rod, forging the MT shank, heat treatment to 62–65 HRC, grinding the tapered web, and applying TiAlN coating. We also explain how CNC grinding achieves concentricity below 0.015 mm TIR and a surface finish of Ra 0.4 µm.

Product Description

Mining Rock Drill Bits specification:

1.Product Name:Tungsten carbide Mining Rock Drill Bits.

2.Application:Mining Rock Drill Bits can be used for drilling granites,marble quarry,mining,railway, tunnel etc.

3.Feature:Mining Rock Drill Bits connect to jack hammer for drilling holes.

4.Material:High quality carbide for buttons and high quality steel for bit body.

5.MOQ:No requirement for testing and trial order

 

Name	Mining Rock Drill Bits
Material	Steel & Carbide
Type	Chisel/Cross/Button Bits
Application	Mining,Quarrying,Ground Engineering,Tunnel Project
Advantage	1.High Quality & Competitive Price 2.China Top 3 Manufacturer 3.Good After Service
Certification	ISO9001
Package	1pc/Opp Bag,50pcs/Plastic Box
Delivery	Usually Within 30 Days(10 Days with Stock)
Payment Term	TT/Western Union/LC
MOQ	No Request With Trial Order

 

The defining feature of a Morse Taper Drill Bit is the conical shank (MT1, MT2, MT3, MT4, MT5). Unlike a straight shank, a Morse taper utilizes the wedge principle. When the male taper of the bit is seated into the female socket of the spindle, the friction bond is so strong that it transmits high torque without a drawbar (though drawbars are often used for safety on larger sizes like MT3 and above).

• Self-Holding vs. Self-Releasing: Morse tapers are "self-holding." The deeper they are seated, the tighter they grip.

• Removal: A drift (wedge) is inserted through a slot in the spindle to break the friction seal.

• A common point of confusion in SEO is the distinction between Taper Shank Drill Bits (MT shank) and Taper Length Drill Bits (long flute length).

• Taper Shank: Refers to the mounting style (Morse taper). Used for high torque.

• Taper Length: Refers to the flute length, typically 8x to 12x the diameter (longer than a jobber but shorter than an aircraft extension). 

• High-Speed Steel (HSS)

• Standard HSS (often referred to as M2) is the most common material for general-purpose taper bits.

• Composition: Carbon, Chromium, Vanadium, Molybdenum, and Tungsten.

• Performance: Good toughness, resists breakage in interrupted cuts.

• Application: Drilling wood, plastics, and mild steels with a tensile strength

• Taper Rock Bit (Carbide Button Bits): Used in mining. The steel body is forged, and tungsten carbide buttons are pressed into the gauge. These are designed for percussive drilling in hard rock (granite, basalt). 

• Tapered Web Thickness: A design variant where the core thickness increases towards the shank. This provides superior rigidity during deep drilling and has been shown to reduce hole diameter errors compared to standard geometries. 

 Cobalt HSS (HSCo/M35)

For high-heat applications like stainless steel, HSCo or M35 Cobalt is the industry standard.

• Composition: HSS base with 5% or 8% Cobalt.

• Performance: Retains hardness at red heat (up to 650°C). It is less tough than standard HSS but offers superior wear life.

• Application: Drilling stainless steel (austenitic and martensitic), titanium, and high-alloy steels up to 1200 N/mm². Premium brands like Würth’s “VaryTap” utilize HSCo for blind hole applications.

Manufacturing Process – Milled vs. Fully Ground

This is the most critical engineering distinction in manufacturing. A CNC ground drill bit is vastly superior to a milled one. The chart below explains the quantitative differences. 

The Milling Process (Economy)

1. Turning: The Morse taper is turned on a lathe. This leaves visible concentric turning marks.

2. Flute Milling: A rotating cutter mills the helix into the blank. This process is fast but leaves "feed lines" inside the flute, acting as stress risers and friction points.

3. Point Grinding: Only the tip is ground.

The Full Grinding Process (Premium)

1. Single Setup: The blank is loaded into a 5-axis CNC tool grinder.

2. Grinding: A single wheel or sequence of wheels grinds the Morse taper, the flutes, the lands (backing off the Cutting edge), and the point (including split point thinning) in one operation.

3. Result: Perfect concentricity. The polish on the flutes ensures chips slide out easily, reducing the risk of jamming in blind holes.