Drill Bit Characteristics
– Spiral controls chip removal
– Fast spiral used for high feed rate applications
– Low spiral used for cutting applications prone to clogging
– Point angle determined by material hardness
– Lip angle determines cutting edge support
Drill Bit Length, Shank Types, and Diameter
– Functional length determines hole depth and bit stiffness
– Longer bits may result in inaccurate hole location
– Standard lengths include Stub, Jobber, and Taper
– Straight shanks common for consumer use
– Tapered and hex-shaped shanks for heavy-duty drilling
– Diameter-to-length ratio usually between 1:1 and 1:10
– Higher ratios pose technical challenges
– Geometry selection depends on material properties
– Recommended geometries for commonly drilled materials
– Different materials used for drill bits based on application
Drill Bit Materials and Coatings
– Soft low-carbon steel bits for drilling wood
– High-carbon steel bits more durable, suitable for wood or metal
– High-speed steel (HSS) bits resistant to heat, used for various materials
– Cobalt steel alloys used for drilling stainless steel and hard materials
– Tungsten carbide and other carbides drill virtually all materials
– Black oxide coating provides heat and corrosion resistance
– Titanium nitride (TiN) coating extends cutting life of high-speed steel bits
– Diamond-coated bits used for drilling glass and other materials
– Coatings increase the lifespan of drill bits
– PCD (polycrystalline diamond) bits resist wear and are used for abrasive materials
Different Types of Drill Bits
– Twist drill bit: most commonly produced type, invented by Sir Joseph Whitworth and improved by Steven A. Morse, range in diameter from 0.002 to 3.5in, crucial geometry and sharpening for performance
– Step drill bit: tip ground down to a different diameter, used for counterboring or countersinking
– Unibit: roughly conical bit with a stairstep profile, used for drilling a wide range of hole sizes
– Center Drill Bit: used for creating a conical hole in between centers manufacturing processes
– Spotting Drill Bit: provides a starting point for drilling on unprepared surfaces
– Core Drill Bit: used to enlarge existing holes, ensures clean and centered results
– Countersink Bit: cuts conical holes into manufactured objects, provides a neat and finished appearance
– Indexable Drill Bit: primarily used in CNC and high precision equipment, utilizes replaceable carbide or ceramic inserts for cutting
Drill Bits for Specific Materials and Applications
– Metal spade bit: two-part bit with a tool holder and an insertable tip, capable of cutting to a depth of about 10 times the bit diameter
– Straight fluted bit: used when drilling copper or brass to prevent digging in or grabbing the material
– Trepan (BTA drill bit): cuts an annulus and leaves a center core, used for cutting large diameters and deep holes
– Brad point bit: optimized for drilling in wood, produces clean holes by cutting the periphery first
– Wood spade bit: used for rough boring in wood, suitable for high-speed use with electric hand drills
– Center bit: optimized for drilling in wood with a hand brace, radial cutting edges remove a slice of wood for each rotation
– Auger bit: similar to center bits, available in various sizes, commonly used for hand braces
– Gimlet bit: used in hand brace for drilling small holes in wood, cuts the side of the hole
– Hinge sinker bit: custom drill bit design for particle board or MDF, hinge uses walls of a 35mm diameter hole for support
– Adjustable wood bits: small center pilot bit with adjustable sliding cutting edge, allows drilling a wide variety of hole sizes
Note: The content has been organized based on the provided information. There may be additional ways to group the content depending on the specific context or requirements. Source: https://en.wikipedia.org/wiki/Drill_bit
This article's lead section contains information that is not included elsewhere in the article. (August 2023) |
This article needs additional citations for verification. (July 2021) |
Drill bits are cutting tools used in a drill to remove material to create holes, almost always of circular cross-section. Drill bits come in many sizes and shapes and can create different kinds of holes in many different materials. In order to create holes drill bits are usually attached to a drill, which powers them to cut through the workpiece, typically by rotation. The drill will grasp the upper end of a bit called the shank in the chuck.
Drills come in standardized drill bit sizes. A comprehensive drill bit and tap size chart lists metric and imperial sized drills alongside the required screw tap sizes. There are also certain specialized drill bits that can create holes with a non-circular cross-section.
