CNC machines used for manufacturing

1. 2017
MECHANICS OF MATERIAL LAB
ASSIGNMENT
SUBMITTED BY: SUHAIL AHMED
BSAMT02161001
SEMESTER#03
BS AIRCRAFT MAINTENANCE
TECHNOLOGY
LAB ASSIGNMENT: MACHINES
SUBMITTED TO: MR DAWOOD
BUKHARI
DATE: 14 April 2017

2. Machine: A machine is a tool containing one or more parts that uses energy to
perform an intended action. Machines are usually powered by chemical, thermal,
or electrical means, and are often motorized. Historically, a power tool also
required moving parts to classify as a machine.
Two Types:
Conventional Machines
Non-conventional machines
Conventional machines:
Conventional machines are those which usually usean automatic operation
and less amount of worker is required for use machine
Non-conventional machine:
Non-Conventionalmachines ae thosewhich are usually manually operated
and required large amount of workers to operate the machine.
Lathe machine: A lathe is a tool that rotates the workpieceon its axis to
performvarious operations such as cutting, sanding, knurling, drilling,
or deformation, facing, turning, with tools that are applied to the workpieceto
create an object with symmetry aboutan rotation. Lathes are used
in woodturning, metalworking, metal spinning, thermal spraying, parts
reclamation, and glass-working.
Working Principle: Thelathe is a machine tool which holds the workpiecebetween
two rigid and strong supports called centers or in a chuck or face plate which
revolves. The cutting tool is rigidly held and supported in a tool post which is fed
against the revolving work. The normal cutting operations are performed with the
cutting tool fed either parallel or at right angles to the axis of the work. Thecutting
tool may also be fed at an angle relative to the axis of work for machining tapers
and angles.

3. Construction: Themain parts of the lathe arethe bed, headstock, quick changing
gear box, carriage and tailstock.

4. Surface Grinding: Surface grinding is used to produce a smooth finish on flat
surfaces. Itis a widely used abrasivemachining process in which a spinning wheel
covered in rough particles (grinding wheel) cuts chips of metallic or nonmetallic
substance from a workpiece, making a face of it flat or smooth.
The benefits of surfacegrinding are:
• You can grind very hard or abrasivematerials
• High degree of dimensional accuracy
• Produces surfacetextures of very high finish
• Tooling is less expensive
• Work holding is easier becauseof magnetic chuck
• Can be done automatically
Types:
Horizontal-spindle (peripheral) surface grinding machine:
The periphery (flat edge) of the wheel is in contact with the workpiece, producing
the flat surface. Peripheral grinding is used in high-precision work on simple flat
surfaces, tapers or angled surfaces, slots, flat surfaces next to shoulders, recessed
surfaces, and profiles.

5. Vertical-spindle surface grinding machine:
The face of a wheel (cup, cylinder, disc, or segmental wheel) is used on the flat
surface. Wheel-face grinding is often used for fast material removal, but some
machines can accomplish high-precision work. The workpiece is held on a
reciprocating table, which can be varied according to the task, or a rotary-table
machine, with continuousor indexed rotation. Indexingallowsloading or unloading
one station while grinding operations are being performed on another.
WorkingPrinciple:Surfacegrindingisthemostcommonof thegrinding operations.
It is a finishing process that uses a rotating abrasive wheel to smooth the flat
surface of metallic or nonmetallic materials to give them a more refined look by
removingthe oxide layer and impurities on workpiecesurfaces.Thiswill also attain
a desired surface for a functional purpose. Factors to consider in surfacegrinding
are the material of the grinding wheel and the material of the piece being worked
on.

6. Typical workpiece materials include cast iron and mild steel. These two materials
don't tend to clog the grinding wheel while being processed. Other materials are
aluminum, stainless steel, brass and some plastics. When grinding at high
temperatures, the material tends to become weakened and is more inclined to
corrode. This can also result in a loss of magnetism in materials where this is
applicable.
Milling Machine: are tools designed to machine metal, wood, and other solid
materials. Often automated, milling machines can be positioned in either vertical
or horizontalorientation to carve out materials based on a pre-existing
design. Milling machines are capable of dynamic movement, both of the tool and
the workpiece, and many milling machines can performmulti-axis machining.
Because of variations in orientation, operation and application, milling machines
have varying functions and different operating principles. Milling machines can be
outfitted with a number of tool heads to accomplish different machining needs.
Some of these tool heads include cutters, rounding mills, fluted mills and ball end
mills. Some milling machines have rotating tool ends that can change depending
on the needed task.
Working Principle: Theworkpieceis holding on the worktableof the machine. The
table movement controls the feed of workpiece against the rotating cutter. The
cutter is mounted on a spindle or arbor and revolves at high speed. Except for
rotation the cutter has no other motion. As
the workpiece advances, the cutter teeth
remove the metal from the surface of
workpiece and the desired shape is
produced.

7. Drilling machine:
A device, usually motordriven, fitted with an end cutting tool that is rotated with s
ufficient power either to create a holeor to enlarge an existing hole in a solid mat
erial. Also known as driller.
A machine for making holes with removal of chips. Drilling machines are used for
drilling, boring, countersinking, reaming,and tapping. Several types are used in me
talworking: vertical drilling machines, horizontal drilling machines, center drilling
machines, gang drilling machines, multiple spindle drilling machines, and special-
purpose drilling machines.
Working principle: The rotating edge of the drill exerts a large force on the
workpiece and the hole is generated. The removal of metal in a drilling operation
is by shearing and extrusion.
Construction: The machine has only a hand feed mechanism for feeding the tool
into the workpiece. This enables the operator to feel how the drill is cutting and
accordingly he can controlthe down feed pressure. Sensitive drill presses are
manufactured in bench or floor models, i.e., the base of machine may be mounted
on a bench or floor. The main operating parts of a sensitivemachine/drill press
are Base, Column, Table, and Drill Head.

8. Power Hacksaw: Power hacksaws areused to cut large sizes (sections) of metals
such as steel. Cutting diameters of more than 10/15mm is very hard work with a
normal hand held hacksaw. Therefore power hacksaws have been developed to
carry out the difficult and time consuming work.
The heavy ‘arm’ moves backwards and forwards,cutting on the backwards stroke.
Working principle: Power hacksaws have electric motors that power the blade
through a pulley system. Some have ratchet systems. The pulley system shown
below shows how rotary power is transferred from the motor and changed to
reciprocating motion, allow the blade to cut through the material.
Most power hacksaws havetwo pulley wheels. If the belt is placed on the smaller
pulley wheel the speed of cut will be fast. Changing the belt so that it runs round
the larger pulley wheel will reduce the speed.

9. Grinding Machine: Grinding is the most common type of material cutting and
surfacegeneration process.Mostlygrindingprocessisusedto shapeand to provide
better finishing parts of metals. Grinding process uses one abrasive tool to make
controlled contact with workpiece surface. Normally grinding wheel is used as
abrasive tool in process of grinding. Grinding wheel will have grains of abrasive
materials and these grains of abrasive material will be termed as grit.
Working principle: A grinder is manually operated and normally has two wheels of
different grain sizes that are fixed on a floor stand or work bench; to perform
roughing and finishing operations. Itis mainly used to shapetool bits; and repair or
makevarioustools. A belt grinderincludes a machining processto grind metals and
other materials, with the help of coated abrasives. Belt grinding is a versatile
process that involves several kinds of applications such as stock removal and
finishing. Size of abrasivematerials plays a very important role in grinding process
as larger sizegrains willremovematerial faster fromworkpiecesurfacebutwillnot
providebetter surfacefinish,whereassmallergrain sizewill removematerial slowly
from workpiece surface but will provide better surface finish.