Drilling Machine: Definition, Parts, Types, and Operations [PDF]

A drilling machine is one of the important machine tools in the workshop. Although lathe machines can also perform drilling operations, drilling machines are specifically designed for handy operations. When we require a large number of drilling operations, we opt for using a drilling machine. This machine is capable of performing drilling, reaming, and boring operations, and is used to create holes of various sizes on a job by removing metal.

In this article, we will discuss the definition, parts, types, and operations of the drilling machine you should know about. Also at the end of the article, you will be able to download the pdf of the entire article.

What is Drilling Process?

Drilling is a material-removing or cutting process in which the tool uses a drill bit to cut a hole of circular cross-section in solid materials. This is the most common machining process, one estimate is that 75% of all metal cutting material removed comes from the drilling operation.

Read More : 5 Best Drill Machines of 2023

Drilling Machine Definition

A drilling machine is a tool that is used to create cylindrical holes or other shapes in a material such as metal, wood, or plastic. It is a versatile machine that has a rotating drill bit that is designed to penetrate the material and create a hole of a specific size and depth. Drilling machines are commonly used in factories, workshops, construction sites, and other settings where precise and efficient hole-making is required. Overall, drilling machines play a crucial role in a variety of industries and are essential tools for creating accurate and precise holes.

Drilling Machine Parts

A drilling machine consists of the following parts:

• Base
• Column or Pillar
• Arm
• Worktable
• Drill head
• Feed Mechanism
• Spindle
• Drill jigs
• Chuck
• Electric Motor
• Pully or gears

Base

The foundation of a drilling machine plays a vital role as it supports the entire weight of the machine and transfers it to the ground. Typically constructed of cast iron or steel, the base is exceptionally sturdy. Slots are provided on the top of the base to support larger jobs, and a radial column or pillar is located on one side of the base. Depending on the design, the base can be bolted to the ground or supported by two or four legs.

Column or pillar

Typically located on one side of the base, the column or pillar is designed to allow for the arm’s movement in a clockwise or counterclockwise direction. A radial column is commonly used for this purpose. Constructed of cast iron or steel, the column is also incredibly sturdy to support the load of the arm and drill head. A sliding table is affixed to the column, providing the necessary up and down motion required for the task at hand.

Upper arm

The upper arm, situated atop the column, supports both the drill head and the housing for the driving mechanism. It is constructed of the same sturdy material as the base to ensure the entire structure is rigid. In certain drilling machines, a guideway is incorporated to enable the drill head to slide along it.

Worktable

Mounted on the column, the worktable is typically constructed of cast iron and features T-slots on its top surface. Some tables also come equipped with a vice to aid in job holding. The table can be adjusted both up and down and right or left, depending on the job and tool arrangement. The table’s vertical motion can be achieved manually or via an electrical mechanism, with a rack and pinion mechanism commonly used for this purpose. Worktable shapes can be rectangular or circular, depending on the machine’s design.

Drill head

The drill head is mounted on one side of the arm and is comprised of various feed and driving mechanisms. A drill chuck is affixed to the head, allowing for the attachment of drill bits. The drill head can be moved up and down to accommodate the job’s requirements. To transfer power from the motor to the pulley and, subsequently, from the pulley to the drill head, a V-type belt is employed. This belt enables the transfer of mechanical power from the motor to the drill head.

The different types of speed can be generated by the following two methods:

Cone Pully Mechanism

Gear-Train Mechanism

Feed Mechanism

To transfer power from the electric motor to the spindle, a combination of a V-belt and pulley system is employed in the drill machine. The drill head’s up and down motion is facilitated by both manual and automatic feed mechanisms. An electrical motor can be utilized to provide automatic feed, with a rack and pinion system converting rotational movement into straight-line motion. Similarly, for manual feed, a rack and pinion mechanism is also used, allowing the operator to adjust the drill head’s height as required.

Spindle

The drill chuck is held in place by a circular taper shaft, typically made of high carbon chromium steel, stainless steel, or steel alloys. This shaft is responsible for transferring the rotary motion from the drill head to the drill jigs. To facilitate the swapping out of drill chucks, a keyhole is provided on the spindle. The spindle can also move up and down via a rack and pinion mechanism. This allows for greater flexibility in adjusting the drill head’s height to accommodate the job’s requirements.

Chuck

The drill chuck is located on the lower end of the spindle and is responsible for holding the drill jig in place. As with the spindle, a keyhole is provided for easy changing of the drill jigs. Drill chucks used in drill machines are typically self-centering and often utilize a three-jaw chuck. These chucks are commonly made of special alloy steel, chosen for their strength and durability.

Electric Motor

A single-phase AC motor is commonly used in drilling machines, which typically runs at a speed of 600-5000 RPM. However, for high-duty drilling machines, the motor may run at even higher speeds.

Pully or gears

Power transmission in drilling machines is achieved using pulleys or gears, with bevel gears used to transmit power at a 90-degree angle. A single-phase AC motor is typically used, with an RPM of 600-5000 or more for high-duty machines.

How does Power Transmission happen in the Drilling machine?

The drilling machine transmits power from an electric motor using a V-belt and pulley. The spindle speed is adjusted by changing the position of the belt on the pulley stack. The bevel gear is used to transmit power at a 90-degree angle.

Drilling Machine Types

In the market there are various types of Drilling machine available. Following are some of the popular types of drilling machines.

• Sensitive Drilling Machine
• Vertical or Pillar
• Radial Arm
• Gang Type
• Multi-Spindle
• Numerically control
• Special Purpose Drilling Machine

Sensitive Drilling Machine

The sensitive drilling machine has a hand-feed mechanism for controlling the tool’s feed into the workpiece, allowing the operator to feel the drill’s cutting and adjust the down feed pressure accordingly.

Vertical or Pillar Drilling Machine

The Vertical or Pillar Drilling Machine is sturdy and can handle larger drills with its heavy frame. It comes with an adjustable table height and offers power speed and feeds. The drills typically have a standardized taper shank within a taper bore in the spindle end, known as Morse tapers.

Radial Arm Drilling Machine

The radial drill machine is used for heavy and large work, with a power-driven arm for height location and motorized drill head positioning. The workpiece remains stationary on the machine base or worktable, and the machine spindle is moved to the required location.

Gang Type Drilling Machine

In a Gang type Drilling Machine, multiple spindles or stations are mounted on a long table, allowing for simultaneous drilling on multiple workpieces.

Multi-spindle Drilling Machine

Yes, that’s correct. A multi-spindle drilling machine has multiple spindles mounted on a single machine head, allowing multiple holes to be drilled simultaneously in a single workpiece. The spindles can be adjusted to different distances from each other, and the machine can be set up to drill holes in various patterns, such as in a straight line or in a circular pattern. These machines are often used in high-volume production environments where efficiency and speed are crucial.

Numerical Control Drilling Machine

A numerical control drilling machine is capable of automatically changing tooling through a turret or automatic tool changer. It operates using a computer program that controls speeds, feeds, and table position, allowing for precise and efficient drilling operations.

Twist drill nomenclature

It is designed with cones like internal structure, narrow at the top of the web with a gradually increasing thickness to the shank. It is a multi-point cutting tool.

Read More : single-point cutting tool

Properties of Twist Drill

Axis:

The imaginary straight line which forms the longitudinal centerline of the drill.

Back taper

A slight decrease in diameter from front to back in the body of the drill.

Body 

The portion of the drill extending from the sank or next 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 end of the web that connects the cutting lips.

Chisel Edge Angle 

The angle included between the chisel angle and the cutting lips 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 Street grooves cut or formed in the body of the drill to provide cutting lips, to permit removal of chips and to allow cutting Fluids to reach the cutting lips.

Flute Length 

The length from the outer corners of the cutting lips to the extreme back and of the flutes; it includes the sweep of the tool used to generate the flutes and, therefore does not indicate the usable length of the flutes.

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 body between adjacent flutes.

Land Width 

The distance between the leading edge and the hill of the land measured at the right angle to the leading edge.

Lead 

The axial advance of the leading edge of the land in one turn around the circumference.

Lips 

The cutting edge of a two-flute drill extending from the chisel edge 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 onto a plane tangent to the Periphery at the outer corner of the lip.

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 a straight shank drill, nor does it include the conical cutting point used on both straight and taper shank drills.

Point 

The cutting end of the drill made up of the end of the lands and the web; inform it resembles a cone, but departs from a true cone to furnish clearance behind the cutting lips.

Point angle 

The angle included between the cutting lips projected upon a plane parallel to the drill axis and parallel to the two cutting lips.

Shank

The part of the drill by which it is held and driven.

Tang 

The flattened end of a tapered shank intended to fit into a driving slot in a socket.

Tang drive 

Two opposite parallel driving flats on the extreme end of a straight Shank.

Web 

The central portion of the body that joins the land; the extreme end of the web forms the chisel edge is on a two-flute drill.

Drilling Machine Operation

These are the following operations that can be performed in the Drilling machine.

• Plane drilling operation
• Core drilling operation
• Step drilling operation
• Boring operation
• Counter boring operation
• Reaming operation
• Countersinking operation
• Spot facing operation
• Tapping operation
• Trepanning operation

Plane Drilling operation

Drilling operation is used to create circular holes in a workpiece of any size. A drill machine is appropriate for this operation, although a lathe can also be used. The cutting tool used is called a drill bit, which is a multipoint rotary cutting tool that removes material from the workpiece. The drill bit has a conical internal structure that narrows towards the top of the web and gradually increases in thickness towards the shank.

Core Drilling

Sand castings often require cores to displace metal where holes are needed. During the casting process, molten metal flows around the core and solidifies, leaving rough holes. To clean up the hole sidewalls, a heavy-duty drill is typically used.

Step Drilling

More than one diameter can be ground on the drill body which saves an extra operation.

Boring

The boring operation is used when you want to increase the diameter of an existing hole. However, the accuracy of this operation is not as high as the reaming operation. In this operation, a single-point cutting tool is generally used as the boring tool.

Reaming

Reaming is a finishing operation for drilled holes to achieve accurate size and smooth surface. The diameter should be consistent and the hole should be perfectly round. When precision is required, reaming is preferred over drilling. Reaming involves using a reamer, which has multiple cutting edges and removes material from the existing hole to achieve the desired accuracy.

Counter Boring

Counterboring is a machining operation where a second hole is bored concentrically with a smaller diameter hole, but with a larger diameter. This operation is typically done using a tool called a counterbore on a drilling machine. The pilot, a small diameter on the end of the tool, keeps the counterbore aligned with the original hole. Pilots can be replaced with others of different sizes to suit various hole sizes.

Counter Sinking

Countersinking is a process of creating an angled surface at the end of a hole using a countersink tool. The tool is available in various diameters and angles, depending on the application. The angle of the countersink depends on the type of screw or rivet head to be used. For instance, a flathead screw requires an 82-degree included angle, whereas a center hole needs to be 60 degrees. Rivet heads can have included angles ranging from 90 to 145 degrees.

Spot Facing

Spot facing is an operation where a flat, circular surface is machined around a hole to provide a seat for a bolt head, nut or washer. This operation is typically performed on castings. A counterbore can be used for spot facing. The machined surface should be square with the hole.

Tapping

Before tapping holes, they are first drilled to a specific size. To tap holes using a standard drilling machine, a tapping attachment is necessary. The attachment is held in the spindle of the drill press by a tapered arbor that drives a friction-type mechanism. The tap holding chuck precisely centers the tap on the round part of the shank, while floating jaws hold the tap on its square end in a sturdy and stable grip. This prevents the tap from pulling out of the chuck when reversing.

Trepanning

Trepanning is a machining process that involves producing a large hole in a workpiece by creating an annular groove, which leaves a solid cylindrical core in the center. To perform this operation, a cutter is used, which consists of one or more cutting edges placed along the circumference of a circle. Trepanning is typically used when a hole with a diameter of more than 50 mm is required, and hole depths of up to 160 times the diameter can be achieved using this method.

Drilling Machine Advantages

• This machine is needed to mark on the end of components of dresses especially for setting pocket, dart & so on
• It can make the hole permanently for a long
• It can perform a wide variety of operations
• It can produce consistent holes

Drilling Machine Disadvantages

• The use of a machine is limited
• They have limitations in terms of the maximum hole size
• The accuracy of the hole may be affected by the quality of the drill bit
• There may be limitations on the maximum depth of the hole that can be drilled.

Drilling Machine Application

• It is used to make a hole in the fabric for button attaching and to make a reference mark for attaching different small components on the garments. 
• They are used in metalworking industries for drilling holes in metal sheets and plates, bars, etc.
• They are used for drilling holes in engine blocks, cylinders, and other automotive parts.
• They are used to drill holes in concrete, brick, and other building materials.

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Conclusion

In conclusion, a drill machine is an essential tool for professional contractor. It is a versatile piece of equipment that can be used for a wide range of tasks. From drilling holes to driving screws and bolts. When choosing a drill machine, it is important to consider the power, speed, and size of the tool, as well as the type of chuck and battery. With the right drill machine and proper precautions, users can achieve precise and efficient results in their projects.