This document discusses the drilling process as a manufacturing technique. It begins with definitions of manufacturing and manufacturing processes in general. It then describes drilling as a process that makes circular holes using a rotating cutting tool called a drill bit. Various types of drilling processes are outlined, including spot drilling, center drilling, deep hole drilling, gun drilling, trepanning, microdrilling, vibration drilling and orbital drilling. The document also discusses drilling in different materials like metals and wood, outlining techniques and challenges for each.

1. DRILLING PROCESS
MANUFACTURING TECHNOLOGY

2. Manufacturing
Manufacturing is the production of products for use or sale using labor and machines, tools, chemical or biological
processing or formulation and is the essence of secondary industry.
Manufacturing Processes
Manufacturing process are the steps through which products are made from raw material. It begins with product des
and material specifications, then the materials are modified through manufacturing processes.
Types of Manufacturing Processes
1. Casting
2. Forming
3. Moulding
4. Machining
5. Joining
6. Additive Manufacturing
7. Labelling and Painting An industrial worker in KINEX Bearings

3. Drilling
Drilling is a process which is used to make circular holes in a solid material. A rotary (multipoint) cutting tool is
used for this process which is called a drill bit. This drill bit is pressed against the surface and rotated at high speed
which removes the chip as the hole is drilled.
Process
• Drilled holes have sharp edge on entrance and burrs on the exit, with
helical feed marks inside the hole.
• Drilling may affect the mechanical properties of the material as the
material may become more susceptible to corrosion and crack
propagation. So, a finish operation should be done.
• The type of chips formed is an indicator of the machinability of the
material, as long chips suggest good machinability of the material.
• Cutting fluid is commonly used to cool the drill bit, increase tool life,
increase speeds and feeds, increase the surface finish, and aid in
ejecting chips.

4. Types of drilling process
Spot drilling
The purpose of spot drilling is to drill a hole that will act as a guide
for the final hole. The hole is drilled only partly in the surface
because this is used only as a guide.
Center drilling
A small 60° countersink, twist drill is used to make centers in a
piece of
work about to be turned.

5. Deep hole drilling
Deep hole drilling is defined as drilling a hole of depth greater than
ten times the diameter of the hole. These types of holes require
additional equipments for straightness and tolerances. Deep hole
drilling can be achieved by following methods.
A deep hole, several meters long, drilled in granite
Gun Drilling
This is used to drill holes of very small diameters, with depth-to-diameter
ratio of 300:1. The drills used are self-centering bits and were developed to
Drill out gun barrels.
Trepanning
It is used for creating large diameter holes and it removes the desired
diameter by cutting out a solid disc. Eg. Tunnel boring machine

6. Microdrilling
Microdrilling refers to drilling of holes less than 0.5mm. It has its
own challenges because coolant fed drills cannot be used and high
spindle speeds are required.
Vibration drilling
In this type of drilling, the main principle is to generate axial
vibrations along with feed movement of the drill, so that the chips
easily breakup and can be easily removed.
Orbital drilling
Also known as circle interpolating, is based on rotating a cutting
tool around its own axis and simultaneously about a centre axis
which is off-set from the axis of the cutting tool.

7. Material
Drilling in metals
• For the easy removal of the chips, the drill bit has fluting around
it. Sometimes, cutting fluid is used to increase the tool’s life and
for lubrication. It is introduced via holes through the drill shank.
• While cutting aluminium, the cutting fluid ensures a smooth and
accurate hole.
• But in other soft metals, like brass the drill can grab the work
piece and leads to chatter. So, a face of 1-2mm is ground on the
cutting edge to create an obtuse angle of 91- 93 degrees, which
in turn prevents chatter.
• In CNC machine tools, a process called peck drilling is used
which involves plunging the drill partway through the workpiece
and then retracting it to the surface. It is done to reduce the
chip building.
• A magnetic base drilling machine allows drilling in a horizontal
position and even on a ceiling. It is used when it is not possible
to bring the material to the CNC machine. These machines are
widely used in construction, fabrication, marine, and oil & gas
industries.

8. Drilling in wood
• It is easier to drill in wood because they are soft, and cutting
fluids are not needed.
• The main challenge in wood drilling is to keep entry and exit
holes clean, and to avoid burning.
• The problem of burning can be solved by using sharp drill bits
and the appropriate cutting speed.
• For boring clean holes, there are several types of drill bits, like
forstner bits, brad-point bits and hole saws.
• Chipping on exit can be minimized by using a piece of wood as
backing behind the work piece, and the same technique is
sometimes used to keep the hole entry neat.

9. References
• Manufacturing, wikipedia: https://en.wikipedia.org/wiki/Manufacturing
• List of manufacturing processes, wikipedia:
https://en.wikipedia.org/wiki/List_of_manufacturing_processes
• Manufacturing processes, engineering articles: http://www.engineeringarticles.org/manufacturing-
process-meaning-and-types/
• Drilling, wikipedia: https://en.wikipedia.org/wiki/Drilling

10. THANK YOU