The size of drilling machine

Size of a drilling machine :

The drilling machine size varies with the different types of the machine being considered.

A portable drilling machine is specified by the maximum diameter of the drill that it can hold.

The sensitive and upright drilling machines are specified by the diameter of the largest piece that can be centred under the spindle. This is a case of a 600 mm size upright drilling machine, the spindle placed at a distance is slightly greater than 300 mm from the front face of the column.

The size of the radial drilling machine is specified by the diameter of the column and length of the arm. Other particulars such as maximum drilling radius, minimum drilling radius, spindle speeds and feeds etc. 

To specify a drilling machine fully further particulars such as the maximum size of drill that the machine can operate, table diameter, the maximum spindle travel, numbers of spindle speeds and feeds available.

Care for drilling machine

For the long life of drilling machine care of drilling machine must be required. Following points should be required to take care of the drilling machine while performing the drilling process.

• Lubrication is important because of the heat and friction generated by the moving parts. For lubrication follow the manufacturer’s manual for proper lubrication methods. 
• Clean each machine after use. 
• Clean T-slots, grooves and dirt from belts and pulleys. 
• Remove chips after drilling to avoid damage to moving parts. 
• Wipe all spindles and sleeves free of grit to avoid damaging the precision fit. 
• Put oil on all unpainted surfaces to prevent rust. 
• Operate all machines with care to avoid overworking the electric motor.

Special Care :

Operations under adverse conditions require special care. 

If machines are operated under extremely dusty conditions. Operate at the slowest speeds to avoid rapid abrasive wear on the moving parts and lubricate the machines more often. Under extreme cold conditions, start the machines at a slow speed and allow the parts and lubricants to warm up before increasing the speeds. 

Metal becomes very brittle in extreme cold. so do not strike the machines with hard tools. Extreme heat may cause the motor to overheat. or keep on and off the operations to keep the motor running cool.

Drilling machine safety

Drilling machines are one of the more dangerous hand-operated machines so we have to take care before the accident is necessary. Safety procedures during drilling operations will help eliminate accidents, loss of time, and materials.

It is necessary that no damage is done to the operator, the machine tool and the cutting tool. To ensure this, the following points are to be remembered :

• The work should not be held by hand use a holding device to hold the workpiece. 
• Use proper work holding device to hold the work because in drilling machine work tend to rotate along with the drill so it cause damage to the operator.
• Never make any adjustments while the machine is operating. 
• The shank of the drill should be cleaned before it is fitted this will leads to the breakage of a drill.
• Use a brush to clean away chips, not by your hand.
• Keep all loose clothing away from turning tools. 
• Make sure that the cutting tools are running straight before starting the operation.
• Never place any tools on the drilling tables. 
• Care should be taken to ensure whether the belt and gears are connected properly.
• Keep all guards in place while operating. 
• Ease up on the feed as the drill breaks through the work to avoid damaged tools or workplaces.
• Remove all chuck keys and wrenches before operating. 
• Always wear eye protection while operating any drilling machines.

Explore more information: 

1. What is the drilling process?

How to use drilling machine?

A drilling machine is a piece of equipment specifically designed to cut holes in metal, wood, plastic or other materials.

A drilling machine is very useful for many projects because they are more stable and reliable than power drills.

Before using of drilling machine some points keep in mind. points are below :

• Selecting a drill bit for a drilling machine
• Setting a speed on a drilling machine
• Adjust the height of the table on the drilling machine
• Adjust the depth of the desired hole
• Secure the material
• Wear proper safety gear

After that turn on the machine using the on/off switch, then rotate the control handle to lower the drill bit into the workpiece. 

Slowly advance the spindle downward to drill the hole. 

If the hole is greater than four times the width of the drill bit, it is advisable to briefly pull the drill bit clear of the workpiece. and if the hole is smaller take care while first time pulls the drill bit.

This allows excess shavings and chips to escape before proceeding then return the spindle to the starting position and turn the power off.

Drilling machine operation

The operation of drilling consists of producing a hole in an object by forcing a rotating drill against it. A hole in an object by forcing a rotating drill against it.

Drilling machine has done various operation following below :

1. Drilling 
2. Reaming
3. Boring
4. Counter boring
5. Countersinking
6. Spot facing
7. Tapping
8. Trepanning

• Drilling :

Drilling is an operation of producing a circular hole in solid metal by rotating the drill and feeding it through the job.

Before starting the drilling it is necessary to mark the position of the hole on the workpiece.

• Reaming :

Reaming is an operation of sizing and shaping a hole using a tool called reamer.

Reamer is a multitoothed tool designed for a remove relatively small amount of material from a previously drilling hole.

Initially, the hole is drilled slightly smaller in size.

• Boring :

Boring of a process of aligning, sizing and finishing a cylindrical hole.

In boring single point cutting tool which rotates relative to the stationary workpiece.

Boring is often used to enlarge the drilling holes.

• Counter boring :

Counter boring is the operation of enlarging one of an existing hole concentric with the original hole with a square bottom.

A counter tool is known as counterbore it has a pilot.

The pilot enters the previously drilled holes and aligns the tool so that the counterbored hole is concentric with the existing one.

• Countersinking :

Countersinking is performed after the drilling to provide a space for the head of the fastener, such as a screw, to sit flush with the workpiece surface.

A countersink tool enlarges the top portion of an existing hole to a cone-shaped opening.

Common included angle for a countersink tool is 60 82 90 100 118 200 degrees.  

• Spot facing :

Spot facing is the process of producing a flat machined surface generally around a hole perpendicular to the hole axis.

The flat surface allows the bottom of a screw or bolt to seat squarely with the material.

Spot facing is commonly done on castings where the irregular surface is found.

• Tapping :

Tapping is a thread cutting for producing internal thread.

Tapping uses multi-point cutting tool called taps may be done manually or on drilling machine.

• Trepanning :

Trepanning is the process for making large holes in sheet metal.

A small diameter hole is drilled in center for drilling large diameter hole.

Holes up to diameter of 350 mm can be cut by this operation.

Drilling machine types

Drilling is an operation for making drill or hole by removing metal from a workpiece by the cutting tool is called drill.
A drilling machine is made in many different types and sizes.
Each type is designated to handle a class of work or specific job to the best advantage.

Types of  Drilling Machine :

1. Portable drilling machine
2. Sensitive drilling machine

• Bench mounting
• Flour mounting

3. Upright drilling machine

• Round column section 
• Box column section

4. Radial drilling machine

• Plain
• Semi universal
• Universal

5. Gang drilling machine
6. Multiple spindle drilling machine
7. Automatic drilling machine
8. Deep hole drilling machine

• Vertical
• Horizontal

9. Turret drilling machine

Drilling machine parts

The different parts of a drilling machine are shown in the figure below :

1. Base
2. Column
3. Table
4. Head
5. Spindle, quill and drill head assembly
6. Spindle drive and feed mechanism

• Base :

The base is the part of the machine on which vertical column is mounted.

The top of the base in the round column and has T-slots on it so large workpiece and work holding devices may be set up and bolted on it.

• Column

The column is the vertical member of the machine which supports the table and the head containing all the driving mechanism.

The column should be sufficiently rigid so that it can up the entire cutting pressure of the drill.

• Table :

The table is mounted on the column and is provided with T-slots for clamping the work directly on its face.

The table may be round or rectangular in shape.

For centring work below the spindle the table of drilling machine may have three types of adjustment :

• Vertical adjustment
• Radial adjustment
• Circular adjustment

• Head :

The drill head is mounted on the top of the column and houses the driving and feeding mechanism for the spindle.

In some of the machines the drill head may be adjusted up or down for accommodating different heights of work in addition to table adjustment.

• Spindle and drill head assembly :

The spindle is a vertical shaft which holds the drill.

It receives its motion from the top shaft through bevel gears.

• Spindle drive and feed mechanism

The spindle drive mechanism of a drilling machine incorporates and arrangement for obtaining multiple speed of the spindle similar to a lathe to suit to various conditions.

Multiple speed of the spindle may be obtained as follows : 

• By step cone pulley drive
• By step cone pulley drive with one or more back gears
• By gearing

Checklist for drill press operation

• Select material as determined by design constraints.
• Determine the logical order of fabrication.
• Select requirements for machine tool used in the fabrication process.
• Determine work to be done by the drill press. 
• Select the drill press to be used.
• Center punch the material where it is to be drilled. 
• Determine the method of securing the material to the drill press. 
• Select the drill bit to be used (tapered, carbide, etc. …)
• Secure the drill bit in the chuck, or directly in the spindle if it is a tapered bit. 
• Determine the proper rotation speed for the conditions. 
• Adjust the position of the v-belt to give the selected rpm. 
• Check the setup for proper alignment and security. 
• Ensure the bit is not touching the material. 
• Check to ensure there is no loose-fitting clothing. 
• Ensure safety glasses are on properly.
• Turn on the Drill Press. 
• Using the spindle feed handle, slowly move the bit down to drill the material. 
• Move the handle up and down, to reduce heat and break off long strands of waste material. 
• Use lubrication as required. 
• Shut off drill press to check the progress of work. 
• When complete, ensure material is not too hot, and remove material. 
• Remove drill bit and return to storage.
• Clean up waste from floor and drilling machine.

Drilling machine function

The main function of the drilling machine is to make drill holes in various materials with the use of a drilling tool.

The drill press is a powerful machine tool used for drilling holes in various materials.

The drill press is typically used to drill holes, but not isolated to it. With the right attachment, the drill press can countersink, mortise, sand, route designs, tap threads, ream or bore out existing holes.

For that different types of a drilling machine are available with the use of that drilling operation is done.

What is drilling machine

A drilling machine is one of the most important machine tools in a workshop is a material removing or cutting process in which the tool uses a drill bit to cut into solid materials a hole of circular cross-section.

While performing drilling operation rotating edge of a cutting tool known as the twist drill which exerts a large force on the work clamped on a table.

The Egyptians drilled holes about 3000 years ago by bow drills in 1200 B.C.

There are different types of drilling machine used to perform the drilling operation which is following below. 


Types of  Drilling Machine :

1. Portable drilling machine
2. Sensitive drilling machine
3. Upright drilling machine
4. Radial drilling machine
5. Gang drilling machine
6. Multiple spindle drilling machine
7. Automatic drilling machine
8. Deep hole drilling machine

Drilling machine Operations :

1. Drilling
2. Reaming
3. Boring
4. Counterboring
5. Countersinking
6. Spot facing
7. Tapping
8. Lapping
9. Grinding
10. Trepanning

Types of the drill commonly used are : 

• Flat or spade drill
• Straight fluted drill
• Two-lip twist drill

Parallel shank (short series or "Jobbers" twist drill)
Parallel shank (stub series) twist drill
Parallel shank (long series) twist drill
Taper shank twist drill

• Taper shank core drill
• Oil tube drill
• Centre drill

Drill Size :

Drills from 0.2 to 100 mm are commonly produced in the metric system.

In the British system, drills are manufactured in three different sizes.

1. Number Sizes :

The drill size range from No. 1 to No. 80. 

Number 80 is the smallest having diameter equal to 0.0135 inches and the number 1 is the largest diameter equal to 0.228 inches.

2. Letter sizes :

The drill size range from A to Z.

A being the smallest having diameter equal to 0.234 inches and Z being the largest having diameter equal to 0.413 inches.

3. Fractional sizes :

The drill sizes range from 1/64 inch to 5 inches.

Designation of Drill :

Twist drills are designated in the Indian standard system by the series they belong to, the diameter, the I.S. Number and drilling material.

The drill is made in three types, namely, normal (N), hard (H), soft (S).

Thus a long-series 10 mm dia parallel shank twist drill conforming to I.S. Standard, made from carbon steel, type S and point angle 80 degrees are designated as follows. 

Parallel shank twist drill (Long) 10.00 - IS:599-CS-S-80


Drill Material :

For one piece of construction, high-speed steel or carbon steel are used. 

For two-piece of construction and cutting portion, high-speed steel is used.
For two-piece of construction and shank portion carbon steel with a minimum tensile strength of 70 kg per sq mm.

High-speed drills are more widely used due to its greater cutting efficiency.


Cutting Speed :

The cutting speed in a drilling operation is the peripheral speed of a point on the surface of the drill in contact with the work.

It is usually expressed in meters per minute.

 v = Π d n /1000 m per min

Where d is the diameter of the drill in mm and n is the r.p.m of the drill spindle.

Cutting speed of drill depends on several factors which are following below. 

• The kind of material is being drilled. Softer material the higher the speed.
• The cutting tool material. 

For example - Drill of high-speed steel can be operated at about twice the speed of drill of high carbon steel.

• The efficient use of cutting fluid.
• The quality of the surface finish desired.
• The method of holding the work.
• The size, type, and rigidity of the machine.

Feed :

The feed of a drill is the distance the drill moves into the work at each spindle revolution.

The feed per minute may be defined as the axial distance moved by the drill into the work per minute.

Sm = Sr × n

Sm = Feed per minute in mm.
Sr = Feed per revolution in mm.
n = r.p.m of the drill.

The amount of feed is depending upon :

• Material being cut 
• The rigidity of the job and machine
• Depth of hole
• Type of finish desired
• Power available
• Range of feed available

Depth of cut :

Depth of cut in drilling is equal to one half the diameter of the drill.

Thus if d be the diameter of the drill the depth of cut (t) is expressed as :

t = d / 2 mm