Audited Supplier
metric and inch
Customized
DIN, JIS, AISI
Taper-length
Twist Drill Bit
High Speed Steel
Metal Drilling
6mm to 100mm
63-65 HRC
Rolled, Milled and Ground
White, Black
Titanium on Request
stc
Plastic Box
metric and inch
Jiangsu
82075090
Product Description
Twist drills are rotary end-cutting tools having one or more cutting lips and one or more straight or helical flutes for the passage of chips and cutting fluids. Twist drills are made with straight or tapered shanks, but most have straight shanks. All but the smaller sizes are ground with "back taper," reducing the diameter from the point toward the shank, to prevent binding in the hole when the drill is worn.
Straight Shank Drills: Straight shank drills have cylindrical shanks which may be of the same or of a different diameter than the body diameter of the drill and may be made with or without driving flats, tang, or grooves.
Taper Shank Drills: Taper shank drills are preferable to the straight shank type for drilling medium and large size holes. The taper on the shank conforms to one of the tapers in the Morse Series.
Definitions of Twist Drill Terms.-The following definitions are included in the Standard.
Axis: The imaginary straight line which forms the longitudinal center of the drill.
Back Taper: A slight decrease in diameter from point to back in the body of the drill.
Body: The portion of the drill extending from the shank or neck to the outer corners of the cutting lips.
Body Diameter Clearance: That portion of the land that has been cut away so it will not rub against the wall of the hole.
Chisel Edge: The edge at the ends of the web that connects the cutting lips.
Chisel Edge Angle: The angle included between the chisel edge and the cutting lip as viewed from the end of the drill.
Clearance Diameter: The diameter over the cutaway portion of the drill lands.
Drill Diameter: The diameter over the margins of the drill measured at the point.
Flutes: Helical or straight grooves cut or formed in the body of the drill to provide cutting lips, to permit removal of chips, and to allow cutting fluid to reach the cutting lips.
Helix Angle: The angle made by the leading edge of the land with a plane containing the axis of the drill.
Land: The peripheral portion of the drill body between adjacent flutes.
Land Width: The distance between the leading edge and the heel of the land measured at a right angle to the leading edge.
Lips-Two Flute Drill: The cutting edges extending from the chisel edge to the periphery. Lips-Three or Four Flute Drill (Core Drill): The cutting edges extending from the bottom of the chamfer to the periphery.
Lip Relief: The axial relief on the drill point. Lip
Relief Angle: The axial relief angle at the outer corner of the lip. It is measured by projection into a plane tangent to the periphery at the outer corner of the lip. (Lip relief angle is usually measured across the margin of the twist drill.)
Margin: The cylindrical portion of the land which is not cut away to provide clearance.
Neck: The section of reduced diameter between the body and the shank of a drill.
Overall Length: The length from the extreme end of the shank to the outer corners of the cutting lips. It does not include the conical shank end often used on straight shank drills, nor does it include the conical cutting point used on both straight and taper shank drills. (For core drills with an external center on the cutting end it is the same as for two-flute drills. For core drills with an internal center on the cutting end, the overall length is to the extreme ends of the tool.
Point: The cutting end of a drill made up of the ends of the lands, the web, and the lips. In form, it resembles a cone, but departs from a true cone to furnish clearance behind the cutting lips.
Point Angle: The angle included between the lips projected upon a plane parallel to the drill axis and parallel to the cutting lips.
Shank: The part of the drill by which it is held and driven.
Tang: The flattened end of a taper shank, intended to fit into a driving slot in the socket.
Tang Drive: Two opposite parallel driving flats on the end of a straight shank.
Web: The central portion of the body that joins the end of the lands. The end of the web forms the chisel edge on a two-flute drill.
Web Thickness: The thickness of the web at the point unless another specific location is indicated.
Web Thinning: The operation of reducing the web thickness at the point to reduce drilling thrust.
Types of Drill.-Drills may be classified based on the type of shank, number of flutes or hand of cut.
Straight Shank Drills: Those having cylindrical shanks which may be the same or different diameter than the body of the drill. The shank may be with or without driving flats, tang, grooves, or threads.
Taper Shank Drills: Those having conical shanks suitable for direct fitting into tapered holes in machine spindles, driving sleeves, or sockets. Tapered shanks generally have a driving tang.
Two-Flute Drills: The conventional type of drill used for originating holes.
Three-Flute Drills (Core Drills): Drill commonly used for enlarging and finishing drilled, cast or punched holes. They will not produce original holes.
Four-Flute Drills (Core Drills): Used interchangeably with three-flute drills. They are of similar construction except for the number of flutes.
Right-Hand Cut: When viewed from the cutting point, the counterclockwise rotation of a drill in order to cut.
Left-Hand Cut: When viewed from the cutting point, the clockwise rotation of a drill in order to cut.
STC drill bits are made from top quality made in China high speed steel. Our drill bits are made from high speed steel M2 and also M35 (cobalt 5). Sometimes in case on request hss M42 (cobalt 8) and hss pm.
ANSI,DIN, GOST, BS, JIS are most popular standard we can supply.
Special design possible on request.
| Nominal diameter Dh8 mm | Overall length L mm | Shank diameter dh7 mm | Morse taper |
| 12 | 199 | 101 | 2 |
| 13.2 | 199 | 101 | 2 |
| 13.5 | 206 | 108 | 2 |
| 14 | 206 | 108 | 2 |
| 18.25 | 256 | 135 | 3 |
| 18.5 | 256 | 135 | 3 |
| 18.75 | 256 | 135 | 3 |
| 19 | 256 | 135 | 3 |
| 19.25 | 261 | 140 | 3 |
| 19.50 | 261 | 140 | 3 |
| 19.75 | 261 | 140 | 3 |
| 20 | 261 | 140 | 3 |
| 20.25 | 266 | 145 | 3 |
| 20.5 | 266 | 145 | 3 |
| 20.75 | 266 | 145 | 3 |
| 21 | 266 | 145 | 3 |
| 21.25 | 271 | 150 | 3 |
| 21.50 | 271 | 150 | 3 |
| 21.75 | 271 | 150 | 3 |
| 22 | 271 | 150 | 3 |
| 22.25 | 271 | 150 | 3 |
| 22.5 | 276 | 155 | 3 |
| 22.75 | 276 | 155 | 3 |
| 23 | 276 | 155 | 3 |
| 26.75 | 319 | 170 | 4 |
| 27 | 319 | 170 | 4 |
| 27.25 | 319 | 170 | 4 |
| 27.5 | 319 | 170 | 4 |
| 27.75 | 319 | 170 | 4 |
| 28 | 319 | 170 | 4 |
| 28.25 | 324 | 175 | 4 |
| 28.5 | 324 | 175 | 4 |
| 28.75 | 324 | 175 | 4 |
| 29 | 324 | 175 | 4 |
| 29.25 | 324 | 175 | 4 |
| 29.5 | 324 | 175 | 4 |
| 29.75 | 324 | 175 | 4 |
| 30 | 324 | 175 | 4 |
| 30.25 | 329 | 180 | 4 |
| 30.5 | 329 | 180 | 4 |
| 30.75 | 329 | 180 | 4 |
| 31 | 329 | 180 | 4 |
| 31.25 | 329 | 180 | 4 |
| 31.5 | 329 | 180 | 4 |
| 31.75 | 334 | 185 | 4 |
| 40.50 | 392 | 205 | 5 |
| 41 | 392 | 205 | 5 |
| 41.5 | 392 | 205 | 5 |
| 42 | 392 | 205 | 5 |
| 42.5 | 392 | 205 | 5 |
| 43 | 397 | 210 | 5 |
| 43.5 | 397 | 210 | 5 |
| 44 | 397 | 210 | 5 |
| 44.5 | 397 | 210 | 5 |
| 45 | 397 | 210 | 5 |
| 45.5 | 402 | 215 | 5 |
| 46 | 402 | 215 | 5 |
| 46.5 | 402 | 215 | 5 |
| 47 | 402 | 215 | 5 |
| 47.5 | 402 | 215 | 5 |
| 48 | 407 | 220 | 5 |
| 48.5 | 407 | 220 | 5 |
| 49 | 407 | 220 | 5 |
| 49.5 | 407 | 220 | 5 |
| 50 | 407 | 220 | 5 |
