Types Of Drill Bits And Their Uses Pdf

types of drill bits and their uses pdf

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Since their first production in , the popularity of bits using PDC cutters has grown steadily, and they are nearly as common as roller-cone bits in many drilling applications. Also known as high-speed bits, they resemble corkscrews and are some of the most popular bits. They had depths of up to meters and were drilled using bits attached to bamboo poles.

20 Types of Drill Bits (And Their Uses)

Drill bits are cutting tools used 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.

Drill bits come in standard sizes, described in the drill bit sizes article. A comprehensive drill bit and tap size chart lists metric and imperial sized drill bits alongside the required screw tap sizes. There are also certain specialized drill bits that can create holes with a non-circular cross-section. While the term drill may refer to either a drilling machine or a drill bit while in use in a drilling machine, in this article, for clarity, drill bit or bit is used throughout to refer to a bit for use in a drilling machine, and drill refers always to a drilling machine.

Most drill bits for consumer use have straight shanks. For heavy duty drilling in industry, bits with tapered shanks are sometimes used. Other types of shank used include hex-shaped, and various proprietary quick release systems. The diameter-to-length ratio of the drill bit is usually between and Much higher ratios are possible e. The best geometry to use depends upon the properties of the material being drilled.

The following table lists geometries recommended for some commonly drilled materials. Many different materials are used for or on drill bits, depending on the required application. Many hard materials, such as carbides, are much more brittle than steel, and are far more subject to breaking, particularly if the drill is not held at a very constant angle to the workpiece; e. The twist drill bit is the type produced in largest quantity today. It comprises a cutting point at the tip of a cylindrical shaft with helical flutes; the flutes act as an Archimedean screw and lift swarf out of the hole.

The twist drill bit was invented by Steven A. Morse of East Bridgewater, Massachusetts in Nowadays, the drill bit is usually made by rotating the bar while moving it past a grinding wheel to cut the flutes in the same manner as cutting helical gears. Twist drill bits range in diameter from 0. The geometry and sharpening of the cutting edges is crucial to the performance of the bit. Small bits that become blunt are often discarded because sharpening them correctly is difficult and they are cheap to replace.

For larger bits, special grinding jigs are available. A special tool grinder is available for sharpening or reshaping cutting surfaces on twist drill bits in order to optimize the bit for a particular material.

Manufacturers can produce special versions of the twist drill bit, varying the geometry and the materials used, to suit particular machinery and particular materials to be cut.

Twist drill bits are available in the widest choice of tooling materials. However, even for industrial users, most holes are drilled with standard high speed steel bits.

The most common twist drill bit sold in general hardware stores has a point angle of degrees, acceptable for use in wood, metal, plastic, and most other materials, although it does not perform as well as using the optimum angle for each material. In most materials it does not tend to wander or dig in.

A more aggressive angle, such as 90 degrees, is suited for very soft plastics and other materials; it would wear rapidly in hard materials. Such a bit is generally self-starting and can cut very quickly. A shallower angle, such as degrees, is suited for drilling steels and other tougher materials. This style of bit requires a starter hole, but does not bind or suffer premature wear so long as a suitable feed rate is used.

Drill bits with no point angle are used in situations where a blind, flat-bottomed hole is required. These bits are very sensitive to changes in lip angle, and even a slight change can result in an inappropriately fast cutting drill bit that will suffer premature wear.

Long series drill bits are unusually long twist drill bits. However, they are not the best tool for routinely drilling deep holes, as they require frequent withdrawal to clear the flutes of swarf and to prevent breakage of the bit. Instead, gun drill bits are preferred for deep hole drilling. Twist drill bit with Morse taper shank. A step drill bit is a drill bit that has the tip ground down to a different diameter. The transition between this ground diameter and the original diameter is either straight, to form a counterbore, or angled, to form a countersink.

The advantage to this style is that both diameters have the same flute characteristics, which keeps the bit from clogging when drilling in softer materials, such as aluminum; in contrast, a drill bit with a slip-on collar does not have the same benefit. Most of these bits are custom-made for each application, which makes them more expensive. A unibit often called a step drill bit is a roughly conical bit with a stairstep profile. Some bits come to a point and are thus self-starting.

The larger-size bits have blunt tips and are used for hole enlarging. Unibits are commonly used on sheet metal [10] and in general construction.

One drill bit can drill the entire range of holes necessary on a countertop, speeding up installation of fixtures. They are often used on softer materials, such as plywood, particle board, drywall, acrylic, and laminate. They can be used on very thin sheet metal, but metals tend to cause premature bit wear and dulling.

Unibits are ideal for use in electrical work where thin steel, aluminum or plastic boxes and chassis are encountered. The short length of the unibit and ability to vary the diameter of the finished hole is an advantage in chassis or front panel work.

The finished hole can often be made quite smooth and burr-free, especially in plastic. An additional use of unibits is deburring holes left by other bits, as the sharp increase to the next step size allows the cutting edge to scrape burrs off the entry surface of the workpiece.

However, the straight flute is poor at chip ejection, and can cause a burr to be formed on the exit side of the hole, more so than a spiral twist drill bit turning at high speed. The unibit was invented by Harry C. Oakes and patented in Unibit is a trademark of Irwin Industrial Tools. Although it is claimed that the stepped drill was invented by Harry C Noakes it was in fact first produced by Bradley Engineering, Wandsworth, London in the s and named the Bradrad.

It was marketed under this name until the patent was sold to Halls Ltd. Hole saws take the form of a short open cylinder with saw-teeth on the open edge, used for making relatively large holes in thin material.

They remove material only from the edge of the hole, cutting out an intact disc of material, unlike many drills which remove all material in the interior of the hole.

They can be used to make large holes in wood, sheet metal and other materials. Center drill bits , occasionally known as Slocombe drill bits, are used in metalworking to provide a starting hole for a larger-sized drill bit or to make a conical indentation in the end of a workpiece in which to mount a lathe center. In either use, the name seems appropriate, as the bit is either establishing the center of a hole or making a conical hole for a lathe center.

However, the true purpose of a center drill bit is the latter task, while the former task is best done with a spotting drill bit as explained in detail below. Nevertheless, because of the frequent lumping together of both the terminology and the tool use, suppliers may call center drill bits combined-drill-and-countersinks in order to make it unambiguously clear what product is being ordered.

They are numbered from 00 to 10 smallest to largest. Center drill bits are meant to create a conical hole for "between centers" manufacturing processes typically lathe or cylindrical-grinder work. That is, they provide a location for a live, dead, or driven center to locate the part about an axis.

A workpiece machined between centers can be safely removed from one process perhaps turning in a lathe and set up in a later process perhaps a grinding operation with a negligible loss in the co-axiality of features usually total indicator reading TIR less than 0.

Traditional twist drill bits may tend to wander when started on an unprepared surface. Once a bit wanders off course it is difficult to bring it back on center. A center drill bit frequently provides a reasonable starting point as it is short and therefore has a reduced tendency to wander when drilling is started.

While the above is a common use of center drill bits, it is a technically incorrect practice and should not be considered for production use. The correct tool to start a traditionally drilled hole a hole drilled by a high-speed steel HSS twist drill bit is a spotting drill bit or a spot drill bit , as they are referenced in the U.

The included angle of the spotting drill bit should be the same as, or greater than, the conventional drill bit so that the drill bit will then start without undue stress on the bit's corners, which would cause premature failure of the bit and a loss of hole quality. Most modern solid-carbide bits should not be used in conjunction with a spot drill bit or a center drill bit, as solid-carbide bits are specifically designed to start their own hole.

Usually, spot drilling will cause premature failure of the solid-carbide bit and a certain loss of hole quality. If it is deemed necessary to chamfer a hole with a spot or center drill bit when a solid-carbide drill bit is used, it is best practice to do so after the hole is drilled.

When drilling with a hand-held drill the flexibility of the bit is not the primary source of inaccuracy—it is the user's hands. Therefore, for such operations, a center punch is often used to spot the hole center prior to drilling a pilot hole. A bit used to enlarge an existing hole is called a core drill bit. The existing hole may be the result of a core from a casting or a stamped punched hole. The name comes from its first use, for drilling out the hole left by a foundry core , a cylinder placed in a mould for a casting that leaves an irregular hole in the product.

This core drill bit is solid. These core drill bits are similar in appearance to reamers as they have no cutting point or means of starting a hole. They have 3 or 4 flutes which enhances the finish of the hole and ensures the bit cuts evenly. Core drill bits differ from reamers in the amount of material they are intended to remove. A reamer is only intended to enlarge a hole a slight amount which, depending on the reamers size, may be anything from 0.

A core drill bit may be used to double the size of a hole. Using an ordinary two-flute twist drill bit to enlarge the hole resulting from a casting core will not produce a clean result, the result will possibly be out of round, off center and generally of poor finish. The two fluted drill bit also has a tendency to grab on any protuberance such as flash which may occur in the product.

A hollow cylindrical bit which will cut a hole with an annular cross-section and leave the inner cylinder of material the "core" intact, often removing it, is also called a core drill bit or annular cutter. Unlike other drills, the purpose is often to retrieve the core rather than simply to make a hole.

A diamond core drill bit is intended to cut an annular hole in the workpiece.

20 Types of Drill Bits (And Their Uses)

With dozens of drill bit types and thousands of sizes to choose from we'll explain the differences and help you choose the right drill bit for your application. On our web site we have divided these into two categories:. We have only organized them in this fashion to make selection easier. General Description: Twist drill bits are the most common type of drill bit and are used for everyday drilling in all types of material. They are also the most confusing due to the sheer number of size, tip, and material specifications. Length Designations: The length of a twist drill has much to do with its rigidity - a shorter bit will be stronger and less likely to wander or break but may not have the reach needed for all jobs. Twist drill bits for use in automated machinery have an actual length specification e.

For so many reasons we need to make a hole in various materials and there are many ways, you will find to make a hole. Holes are made using a mechanical drill fitted with the appropriate drill bit but we must use the correct drill for the target material. Below is a good selection of different drills for different materials. So, your target should be the making of a hole with the least trouble and without damaging the material. Choosing the correct drilling solution is the key to succeeding in making a clean hole for your screw or bolt. You may need to drill holes of different shapes, size and on different types of materials.

The first thing in any drilling assembly is the bit. This chapter will help the DD gain the knowledge necessary to make intelligent recommendations regarding bit selection. The move toward integrated steerable systems makes it imperative that the DD has some input in the bit selection process because if the steerable BHA is to perform as expected the bit must not only achieve an acceptable penetration rate, but must also last for the desired footage while allowing the DD to directionally control the hole. After the bit is run the driller and the tool pusher and the DD usually grade the dull bit. This makes it easier to evaluate the bits performance and is a valuable tool in making the next bit selection. The second part of this chapter is dedicated to dull bit grading. Objectives of this Chapter.


For a typical drill bit, the angle of the point helps determine what type of material the bit can drill. Twist Bit. A twist bit is the most common type of drill bit for home use. allows you to use a single bit to drill holes with different.


20 Types of Drill Bits (And Their Uses)

Before you can decide which type of drill bit to use for a particular job, you would want to first know their construction and recommended application. With this guide of drill bit types and their applications, you will always use the right drill bit for different applications. Before we get into the drill bit types, we need to understand which materials are used to make the drill bits. The most common materials used in the making of drill bits include the following. Other than the tough materials used in making the drill bits, they will also have special coatings to make them better.

08. Drilling Bits.pdf

Drill bits are cutting tools used 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.

Your Guide to Drill Bits – Free PDF Download

For … Their unique design allows them to channel dust from the hole as they work. Special Purpose Drill Bits In addition to the most common types of bits listed above, there is also a large variety of unique bits that make easy work of certain specialized operations. Drill bit basics The drilling bit industry is changing rapidly in the areas of manufacturing technology and the use of new materials. The first oil wells were drilled in China in the 4th century or earlier. To choose a Standard Drill Bit Sizes Pdf you just need to take advantage of our review, which presents a range of products for any budget and wishes. The Forstner drill is used for boring flat bottomed holes and is ideal for modern kitchen unit hinge holes.

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20 Different Types of Drill Bits & Their Uses 1. 3 Greatly worn tip of cable tool bit. Installer Drill Bit. When you choose a Baker Hughes drill bit, you get the right bit for.


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Your Guide to Drill Bits – Free PDF Download

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Drill bits are a vital element to include in the tool kits of DIY enthusiasts and professionals.

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