Unit 2: Shaping & Planning

 

Manufacturing Process II

Unit: 2 Shaping & Planning

According to WBSCTE revised syllabus of 2022

2.1 Basic concept on shaping and planning operations.
2.2 Classification of shaping machines and planning machines.
2.3 Basic parts and their functions of standard shaper & standard double
housing planner.
2.4 Specification of shaping machines and planning machines.
2.5 Shaping machine operations: Machining horizontal surface, machining vertical
surface, machining angular surface, cutting slots, grooves and keyways, machining
irregular surface, machining splines.
2.6 Cutting parameters and machining time calculation in respect of shaping horizontal
surface (simple numerical).

Shaping

What is Shaping operation?

A shaping process is a machining operation, in which, a single point cutting tool is used to remove materials layer by layer from the surface of the work piece, such that the reciprocating motion is provided to the tool and feed motion is provided to the work piece.

Some Important Information about Shaping

• The name of the machine tool, in which Shaping Process can be done is SHAPER.
• Reciprocating motion means a to-and-fro motion which have a forward stroke and a return stroke.
• Material is removed (metal cutting occurs) in the forward stroke.
• No material is removed in return stroke, it is called Idle Stroke.
• A SHAPER machine tool is generally used to produce Flat Surfaces on a work piece and these surfaces can be horizontal / vertical / inclined.
• One forward stroke + one return stroke of the tool is called one complete stroke.
• Stroke means longitudinal movement of the tool or, cutting direction.
• Feed motion of the work piece occurs in Lateral Direction.
• Reciprocating motion of the tool is the Longitudinal Reciprocating Motion, it is the cutting motion.
• Reciprocating motion of the tool can be obtained by Mechanically or Hydraulically.
• Mechanical Reciprocating motion / Cutting motion can be obtained by Quick-Return Mechanism.

Types of Shaper

1. According to the reciprocating motion to the ram:

a) Crank type shaper, b) Hydraulic shaper

2. According to the position and travel of the ram:

a) Horizontal shaper, b) Vertical shaper, c) Travelling Shaper

3. According to the type of design to the table:
a) Standard shaper, b) Universal shaper,

a) Standard shaper, b) Universal shaper,

4. Based on cutting stroke:

a) Push cut type, b) Draw cut type

Parts Of Shaper Machine

1. Base
2. Column or, Pillar
3. Ram
4. Tool Head
5. Clapper Box
6. Cross Rail
7. Table
8. Saddle
9. Tool Holding Device
10. Work Holding Device

Base:

• It is a heavy and robust cast iron body. The base supports the column or pillar which supports all the working parts such as ram, work-table, drive mechanism, etc.

Column or Pillar:

• The column is a ribbed casting of cellular construction. The ram slideways are provided on the top of the column while the table slideways are machined on the front. The crank and slotted link mechanism that drives the ram is contained within the column. The driving motor, variable speed gearbox, levers, handles, and other controls of shaper are also contained in the column.

Ram:

• Ram is a rigidly braced casting and is located on the top of the column. The ram slides back and forth in dovetail or square ways to transmit power to the cutter. The starting point and the length of the stroke can be adjusted using stroke positioning mechanism and the down feed mechanism.

Tool head:

• It is the device which holds the tool. The tool head slides in a dovetail at the front of the ram utilizing T-bolt sand is fastened to the ram on a circular plate so that it can be rotated for making angular cuts. It can swivel from 0° to 90° in a vertical plane. The tool head can be raised or lowered by hand feed for vertical cuts on the workpiece by its hand crank for precise depth adjustments.

Clapper Box:

• The clapper box is needed because the cutter drags over the work on the return stroke. The clapper box is hinged so that the cutting too] will not dig in. Often this clapper box is automatically raised by mechanical, air, or hydraulic action.

Cross Rail:

• The Cross Rail is a heavy casting attached to the column at its front on the vertical guideways. It carries the horizontal table slideways. The cross rail can be raised or lowered using an elevating screw in order to compensate for different thicknesses of work.

Table:

• It is made of cast iron and has box type construction. It holds and supports the work during the operation and slides along the cross rail to provide feed to the work. T-slots are provided on its top and sides for securing the work to it. The table is moved left and right, usually by hand, to position the work under the cutter when setting up. Then, either by hand or more often automatically, the table is moved sideways to feed the work under the cutter at the end or beginning of each stroke.

Saddle:

• The saddle moves up and down (Y-axis), usually manually, to set the rough position of the depth of cut. The final depth can be set by the hand crank on the tool head.

Tool Holding Device:

• Tool holders are the same as the ones used on at engine lathe, though often larger. The cutter is sharpened with rake and clearance angles similar to lathe tools though the angles are smaller because the work surface is usually flat. These cutters are fastened into the tool holder.

Work Holding Device:

• Work holding is frequently done in a vice. The vice is specially designed for use in shapers and has long ways which allow the jaws to open up to 14″ or more, therefore quite large workpieces can be held. The vise may also have a swivel base so that cuts may be made at an angle. Work that cannot be held in the vice (due to size or shape) is clamped directly to the shaper table in much the same way as parts are secured on milling machine tables.

Specification of a Shaper

The size of a shaper is specified by –

1) The Maximum Length of Stroke or Cut (175 to 900 mm)
2) The type of Drive (Belt Drive or Motor Drive),
3) Floor Space required,
4) Weight of the machine,
5) Cutting to Return Stroke ratio,
6) number and amount of feed,
7) Power Input

Working Principle of Shaper

• A single point cutting tool is held in the tool holder, which is mounted on the ram.
• The work piece is rigidly held in a vice or clamped directly on the table.
• The table may be supported at the outer end.
• The ram reciprocates and thus cutting tool held in tool holder moves forward and backward over the work piece.
• In a standard shaper, cutting of material takes place during the forward stroke of the ram. The backward stroke remains idle and no cutting takes
place during this stroke.
• The feed is given to the work piece and depth of cut is adjusted by moving the tool downward towards the work piece.
• The time taken during the idle stroke is less as compared to forward cutting stroke and this is obtained by quick return mechanism.

Shaping Machine Operations

• Machining Horizontal Surface,
• Machining Vertical Surface,
• Machining Angular Surface,
• Cutting Slots,
• Grooves & Keyways,
• Machining Irregular Surface,
• Machining Splines

Cutting Parameters in Shaping

1. Cutting Speed/ Cutting Velocity (V) (m/min)
2. Feed/ Feed Motion (f) (mm/rev)
3. Depth of Cut (t) (mm)
4. Rotational Speed of the work piece / Spindle Speed (N) (RPM, rpm, revolution per min)

Machining Time Calculation in Shaping

Where,

tm = machining time(min)
B = width of the work piece (mm)
f = Feed Motion (mm/Stroke)
N= Strokes per min (SPM)
L = Length of the work piece

Planning

What is Planning operation?

• A planning process is a machining operation, in which, a single point cutting tool is used to
remove materials layer by layer from the surface of the work piece, such that the RECIPROCATING MOTION is provided to the work piece (work table) and FEED MOTION is provided by the lateral movement of the cutting tool.The machine tool in which planning operation can be performed is called a Planer.

Types of Planner

• Double Housing Planer Machine
• Open Side Planer Machine

• Pit Planer Machine
• Edge Planer Machine and
• Divided Table Planer Machine

Double Housing Planer Machine

Open Side Planer Machine

Pit Planer Machine

Edge Planer Machine

Divided Table Planer Machine

Some Important Information about Planning

• The machine tool in which planning operation can be performed is called a Planer.
• Planer is used to produce horizontal/vertical/inclined flat surfaces like a Shaper.
• Planer is used for Large & Heavy work pieces and machine multiple small work pieces at a time.
• The motion of the work table can be achieved by a rack and pinion drive with a (variable speed) electric motor.
• The reciprocating motion of the work table of a Planer can be achieved by mechanisms like Reversible Motor Drive/Open & Cross Belt Drive/Hydraulic Drive.

Planer Machine Parts

• Bed
• Column or Housing
• Table
• Cross Rail
• Tool Head
• Driving
• Feed Mechanism

• Bed:

a. The bed of a planer having cross ribs similar to box-like casting. It is heavy in weight and very large in size also it supports the column and moving parts of the machine.
b. The bed is made generally longer than the length of the table, almost twice the length. So that the full length of the table may across it. To support the table guideways may be provided on a very large machine.
c. The guideways should be horizontal andparallel to each other. The guideways are lubricated properly and to ensure a continuous and adequate supply of lubricants in modern machines, oil under pressure is pumped into the different parts of the guideways.

• Column or Housing:

a. The housings also called columns like vertical structures placed on each side of the bed and are attached to the sides of the bed. They are heavily mechanized to continue severe forces due to cutting.
b. Cross rail may be made to slide up and down for accommodating different heights of work to the front face of each housing is accurately machined to provide precision ways.
c. Two side-tool head also slide upon it. Planer housing encloses the Cross-rail elevating screw, vertical and cross feed screws for tool heads, counterbalancing weight for the Cross-rail.
d. The planer screws can be operated by hand or power.

• Table:

a. The table of the planer supports the workpiece and reciprocates along with the ways of the bed. The planer table is a heavy rectangular casting that has T-slots provided on the entire length of the table so that the work and work holding devices attached to
it.
b. In the end, a hollow space is left which acts as a carrier for collecting chips. Works can also rest upon the troughs of the planer.
c. The table is made up of one single casting but it is divided by the table of planer there
are two separate tables mounted upon the bed ways.
d. Hydraulic bumpers are attached to the end of the bed to stop the table from overrunning that will give the cushioning effect. If the table overruns, a large cutting tool bolted along the underside of the table which will take a deep cut on a replaceable block absorbing the kinetic energy of the moving table.

Cross Rail:

a. The Cross rail is a casting that connects the two housings. Cross rail provides rigidity to the machine. It occupies the face of the housing and can be clamped at the position by manual, hydraulic devices.
b. The Cross rail when clamped should remain absolutely parallel to the top
surface of the table, i.e. It must be horizontal irrespective of its position.
c. Two tool heads are mounted which are called railhead. It has screws for vertical and cross feed of the tool heads and a screw for elevating the rail. The planer screws can be operated by hand or power.

Tool Head:

a. Tool head is a component assembled to saddle, which has the tool post in it. The
tool post is attached to the head so that on to and from of the table the cutting tool force is raised.
b. The cutting edge of the tool will be saved as of being damage and permits then automatic supply to function with no intrusion.
c. It has Saddle, Swivel base, Vertical Slide, Apron, Clapper box, Clapper block, Tool post, Down feed screw, Apron, clamping bolt, Apron swiveling pin, Mechanism for cross and down-feed of the tool.

Driving and Feed Mechanism:

a. The feed mechanism of the tool head is by the hand of power in a crosswise or in a vertical direction. The drive mechanism is located under the table and The motor drive is at one side of the planer.
b. The size of the planer is specified by the maximum length of the stroke and it is also specified by the largest rectangular size that can be machined.

Planer Machine Working Principle

• The worktable can be move and the tool head of the machine is in a stationary position. The workpiece is fixed on the work table and
• The single point cutting tool is attached to the tool head and now we switch on the machine that means power supply to the machine and the worktable moves forward.
• Hence it cuts the material and it is called cutting stroke. The worktable moves downward there is no cutting of material so this is called the return stroke. The process will be continued unless you change the power supply or others.

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