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.
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.
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.
A drilling machine consists of the following parts:
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.
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.
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.
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.
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:
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.
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.
In a Gang type Drilling Machine, multiple spindles or stations are mounted on a long table, allowing for simultaneous drilling on multiple workpieces.
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.
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.
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.
The imaginary straight line which forms the longitudinal centerline of the drill.
A slight decrease in diameter from front to back in the body of the drill.
The portion of the drill extending from the sank or next to the outer corners of the cutting lips.
That portion of the land that has been cut away so it will not rub against the wall of the hole.
The edge at the end of the web that connects the cutting lips.
The angle included between the chisel angle and the cutting lips as viewed from the end of the drill.
The diameter over the cutaway portion of the drill lands.
The diameter over the margins of the drill measured at the point.
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.
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.
The angle made by the leading edge of the land with a plane containing the axis of the drill.
The peripheral portion of the body between adjacent flutes.
The distance between the leading edge and the hill of the land measured at the right angle to the leading edge.
The axial advance of the leading edge of the land in one turn around the circumference.
The cutting edge of a two-flute drill extending from the chisel edge to the periphery.
The axial relief on the drill point.
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.
The cylindrical portion of the land which is not cut away to provide clearance.
The section of reduced diameter between the body and the shank of a drill.
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.
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.
The angle included between the cutting lips projected upon a plane parallel to the drill axis and parallel to the two cutting lips.
The part of the drill by which it is held and driven.
The flattened end of a tapered shank intended to fit into a driving slot in a socket.
Two opposite parallel driving flats on the extreme end of a straight Shank.
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.
These are the following operations that can be performed in the Drilling machine.
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.
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.
More than one diameter can be ground on the drill body which saves an extra operation.
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 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.
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.
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 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.
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 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.
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