Conventional Machines used in Metal Removal Process and its Operations

 1 Introduction

A machine is a mechanical structure that uses power or hand to shape or form parts made of metal or other materials. The required shape products are produced by using operations like facing, tuning, boring, grinding, shearing, and other forms of deformation. Machines use the different type of tools and dies that does the operations. like turning, cutting, shaping, forming, etc.

2 Conventional Machines used in Metal Removal Process

In conventional machining, there must be direct contact between the tool and the work material. For instance, a fast-rotating cutter made of tool steel is necessary to cut a mild steel workpiece. This method requires physical contact of the cutting tool and workpiece material that needs to be cut.

Based on the manufacturing process, different types of machines are used in the manufacturing industries. The widely used metal removal process machines in the manufacturing industries are lathe machine, drilling machine, milling machine, shaping machine, planning machine, slotting machine, boring machine, grinding machine, and broaching machine

3 Operations

The most widely used conventional machines in the manufacturing industries are lathe, drilling, and milling machines. The operations carried in these machines are discussed below.

i) Lathe machine

a Facing – It is the operation of making the ends of a job flat when the job is usually held in a chuck, and the tool is fed perpendicular to the axis of job rotation.

b Boring –It is the operation of enlarging the hole in a workpiece. The workpiece having its initial hole/bore made either by drilling or by putting a core during casting or the bore made during forging. The tool used for boring is a single- point tool.

d Drilling– Drilling is the operation of making a hole in the end face of the job held in a chuck. The tool used is a drill bit held in a drill chuck, which is mounted in the tailstock in much the same way as the dead centre. The tool used for drilling hole is a multi-point tool.

e Knurling– Knurling is the operation of making roughened surface on a smooth surface of cylindrical jobs using hardened steel knurled in place of a usual lathe tool. The knurled surface of the job helps in holding the job tight by hand.

f Grooving or undercutting – It is the operation of reducing the diameter of a job for a very short length. The reduced surface produced is called groove or undercut. The tool used for grooving is a single- point tool.

g Parting off– It is the operation of separating (or cutting off) usually the finished (or machined) component from the workpiece blank. It is a very common operation on a lathe. The tool used for parting off is a single- point tool.

h Turning–Turning is the operation of removing the excess material from the outer diameter of the workpiece to reducing its diameter.

i Chamfering – It is the operation of turning a slope at the extreme end of the workpiece 

ii) Drilling machine

a Drilling – Drilling is the operation of making a hole in the workpiece.

b Reaming–Reaming is the operation of finishing the drilled hole to very close tolerances,   using a tool called of reamer

   Drilling                         Reaming

c Boring–Boring is the operation of enlarging the diameter of the hole using a drill.

d Counter boring–Counter boring is the operation of enlarging the diameter of a predrilled hole up to only a small depth using a counter boring tool bit.

e Counter sinking–Counter sinking is the operation of making a conical shape hole on the top of a drilled, so that counter sunk head screws can be fitted without their heads projecting out of the job surface.

f Spot facing– Involves removing the small amount of metal from the top of the hole (usually a raised seat made for placing washer, etc.).

g Special operation – Tapping, lapping and grinding operations are also dove on a drilling machine.

Tapping

 iii) Milling machine

a Plain milling or slab milling or peripheral milling– In which a flat surface is produced by a rotating cutter with its axis parallel to the surface being machined.

b Face milling– In which a flat surface is produced at right angle to the axis of the cutter

c Side milling– In which a flat vertical surface is produced on the side of a workpiece using a side milling cutter.

d Straddle milling – In which flat vertical surfaces on both sides of a workpiece are produced using two side milling cutters mounted on the same arbor. Distance between the two cutters is adjusted by using suitable spacing collars Straddle milling is commonly used for making square or hexagonal surfaces

e Gang milling – In which several plain milling cutters of same or different diameters and width, may be used at the same time for the  production of several different parallel horizontal surfaces on the workpiece

f End milling -In which narrow slots, grooves or keyways are produced using an end mill cutter on a vertical milling machine.

h Angular milling – In which angular surfaces such as angular grooves on V-blocks are produced using an angle milling cutter.

i Form milling – In which irregular contours are made using form cutters

j T-slot milling– In which first a plane slot is cut on the work surface using side and face milling cutter. Then the T-slot is cut feeding the T-slot cutter from one end of the plain slot.

k Dovetail milling – In which dovetail surfaces are made using a dovetail cutter

l Saw milling – Is the operation of production of narrow slot and grooves using a saw milling cutter. The process can be used for complete parting off also

4 Conclusions

In the metal removal process, the most widely used conventional machines are lathe, drilling, and milling machines. The operations that can be performed in these machines to produce components are defined with suitable diagrams in this blog.