Design Of Single Point Cutting Tool Nptel

A Planer machine is another machine tool after Lathe, Milling, Drilling, and Shaper Machine in Manufacturing.

Today we will study the Definition, Parts, Working Principle, Mechanism, Operation, Types, and Specification of Planer Machine.

So let's dive in.

Note: You can download PDF easily at the end of the article.

Planer Machine Definition:

A planer is a machine tool primarily designed to produce planes and flat surfaces by a single-point cutting tool.

A planer machine is just like a shaper machine but, it is very large and massive and it is capable of machining heavy jobs which can't be done by the shaper.

The main difference between planer and shaper is that In a planer, the work is loaded over the table and reciprocates past the stationary cutting tool and the feed is given by the lateral movement of the tool but In shaper, the ram holding the tool reciprocates over the stationary work loaded over the table and feed is given by the crosswise movement of the table.

Planer Machine Main Parts:

A planer machine consists of the following parts:

BED
Table or Planten
Housing or Column
Cross rail
Tool head
Driving and
Feed Mechanism

Planer Machine Main Parts — Planer Machine Parts

Now lets study one by one,

Bed:

It is a box-like a cast iron casting with cross ribs.

It is very large and heavy in weight.

The bed supports the column and all the moving parts of the machine.

The length of the bed is twice the length of the table, so that table maybe slide on it. The bed is provided with accurately machined v-type or flat type guideways for smooth sliding of the table.

The bed houses the driving mechanism for the table.

Table:

The table is a rectangular cast iron casting having accurately machined top surface to locate the work accurately.

T- slots are provided on the entire length of the table to hold the work properly and holes are drilled on its surface in regular intervals for supporting the poppets and stop pins.

At each end of the table, a hallowed space is provided to collect the chips and a groove is cut on its side for clamping planer reversing dogs at different positions.

The planer may have a single table or two separate tables mounted on guideways and reciprocates separately or together. Hydraulic bumpers are fitted at the end of the bed to stop the table from overrunning and giving cushioning effect.

Housing or Column:

Housing is a rigid box-like vertical structure fastened on each side of the bed. They are also called as uprights.

These are heavily ribbed to take heavy load during cutting action. The front face of each housing is provided with precision ways for sliding the cross rail up and down and also having two side tool heads slide upon it.

The column houses the cross rail elevating screw, vertical and cross feed screws for tool heads. These screws may be operated by power or hand.

Cross Rail:

It is a rigid cast-iron box-like casting that connects the two housings.

It provides additional rigidity to the machine. The cross rail may be moved up and down on the face of the housing by means of elevating screw and can be clamped at any position and it is parallel to the top surface to the table.

The front face of the cross rail provided with accurately machined guideways for cross-feeding the tool head saddle by means of a screw.

Tool Head:

The planner tool head is similar to that of the shaper in construction and operation.

Tool heads are mounted on a cross rail by a saddle, which moves crosswise to give crossfeed. The swivel base is pivoted on the saddles and it is graduated to 60 degrees on each side, so that which can be tilted at any desired angle for machining angular surfaces by rotating down feed screw.

The apron is fixed on the face of the vertical slide which may be swiveled up to 20 degrees on each side for giving the tool clearance while machining vertical surfaces.

The clipper block is hinged to the clipper box to hold the tool post in which cutting tool is held firmly.

The clipper block lifts the tool head upward during return stroke to prevent the cutting edge of the tool from dragging on the work. The tool heads can be moved up and down by moving the cross rail up and down.

How Planer Machine Works?

Initially, the tool head of the machine is in a stationary position and the worktable can be move.

The tool single point cutting tool is fixed in the tool head and the workpiece is fixed on the work table.

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.

Planer Machine Mechanism:

There is two important planer mechanism:

Table drive mechanism
Feeding mechanism

The different table drive mechanisms are:

Open and cross belt drive
Reversible motor drive (move to 37 slides)
Hydraulic drive

Here I have explained only Open and cross belt drive mechanism.

Open and Crossbelt Drive Mechanism:

This mechanism is used in a small size planer.

The principle operation of the open and cross belt drive is illustrated in the figure.

The countershaft mounted on housing is driven by the motor on which fast and lose pulleys are fixed. By shifting the belt from loose to fast pulley the machine is started or by shifting the belt from fast to loose pulley the machine can be stopped. The small diameter pulley drivers the crossed belt and large diameter pulley drivers the open belt.

The crossed belt further connects to the larger diameter pulleys 3(loose pulley)and 4(fast pulley) which are keyed to the main shaft of the table and the open belt connects the smaller diameter pulleys 1 (loose pulley) and 2(fast pulley) on the main shaft.

When the counter shaft rotates the motion will be transmitted to the main shaft of the table through fast pulleys of the cross or open belt and no motion will be transmitted when the belt is on loose pulley. The motion of the main shaft is transmitted through gear 5, 6 and 7 to the bull gear 8. The bull gear meshes with a rack at the underside of the table, which converts the rotary motion to linear motion thereby table starts reciprocating.

The crossed belt is used for driving the table during a cutting stroke, which gives greater power and less speed by having the greater power and the speed is reduced as the belt connects smaller pulley on the countershaft to the larger pulley (3) on the main shaft of the table.

At the end of the forward cutting stroke. The trip dog mounted on the side of the planer table operates a belt shifter through a lever arrangement, thereby shifting the crossed belt from fast pulley(1) to loose pulley(2).

The motion is now transmitted from the larger pulley on the countershaft to the fast pulley on the main shaft and no motion is transmitted by crossed belt to the main shaft.

When the shaft receives the motion from an open belt, the direction of rotation of the shaft reversed and table starts moving to perform return stroke with a high speed as the open belt connects the larger diameter pulley on the countershaft with the smaller diameter pulley on the main shaft and thus obtaining the quick return motion.

At the end of the return stroke, second trip dog will hit against the belt shifter lever causing the cross belt to shift from loose pulley (4) lever causing the cross belt to shift from loose pulley (4) to fast pulley (3) and open belt to shift from fast pulley (2) to loose pulley (1) to repeat the cycle of cutting stroke and return stroke. The length and position of the stroke may be adjusted by shifting the dog position.

Planer Machine Operation:

The common operation that can be performed in the planer machine are:

Planing Flat horizontal surfaces
Planing Flat vertical surfaces
Planing angular surfaces and machining dovetails
Planing curved surfaces
Planing slots and grooves

Planer Machine Types:

Following are the different types of planers machines generally used:

Double housing Planer Machine
Open side Planer Machine
Pit Planer Machine
Edge or Plate Planer machine
Divided table Planer Machine

Double Housing Planer Machine:

This planer is widely used in most of the workshops.

It consists of a long heavy base with accurately machined guideways on which a table reciprocates.

The bed length is slightly greater than twice the length of the table. Near the middle of the bed, two vertical housings are mounted.

One on each side and these are connected at the top by a cross member as shown in the figure below:

The horizontal cross rail carrying two tool heads slides over the vertical faces of the two housings. These tool heads are moved by hand or power in the crosswise or vertical direction to give the feed.

In addition to these, there are two other tool heads mounted on the vertical face of the housing, which can be moved in a vertical and horizontal direction to give the feed. Mechanical or hydraulic devices may be used to drive the planer table.

Salient features of Double housing Planer Machine:

Following are the salient features of Double housing planer:

These are high speed, heavy-duty and rigid machines.
They ensure a high degree of surface finish.
Work is mounted on a table which reciprocates while the tool is held on the machine frame and fed into the work
Planer can accommodate the work as large as 3000mm*3000mm*18.25mm
It is capable to make deep cuts and apply heavy feeds to finish the work in a short time.
The tool is stationery and work is moving.
Multiple tooling permits machining of more than one surface at a time.
Tools used are heavier, stronger and larger.
Cutting and return speeds are uniform throughout the stroke.
A wide range of cutting and return speeds are available.
Planer consumes heavy power up to 150 horsepower.
It requires a large floor area.

Open side Planer Machine:

It has only one housing on one side of the base on which a cross rail on a table as shown in the figure.

Three tool heads can be mounted on the machine. In this machine, a single housing has to take up the entire load, Therefor it should be rigid and robust to resist the forces.

The cross rail can slide vertically along the guideways of the housing and it carries to tool heads which can be moved horizontally and vertically another tool head is fitted on the housing and it can also be moved horizontally and vertically.

Pit Planer Machine:

A pit planer as shown in the figure.

It has a massive construction in which the table is kept in a pit and it is stationary. The column carrying the cross rail reciprocates on a horizontal rail mounted on both sides of the table as you can see in the figure.

The table of the planer is made a level with the floor, so that very heavy work can be loaded very easily. The cross rail carries two tool heads and these can be moved horizontally and vertically to give the cut.

The driving screw is used for driving the column by means of a motor.

Edge Planer Machine:

This planer is also known as plate planer and it is used for squaring and bevelling the edges of steel plates used for different pressure vessels and in ship buildings works.

The table carries the work that remains stationary. The work can be clamped by air-operated clamps. The tool-head mounted on a carriage moves along two horizontal guide ways on a base front end as shown in the figure.

Edge Planer Machine: — Edge Planer Mchine

The operator can stand on a platform of a carriage and moves along with it. The carriage holding the tool reciprocates past the edge of the plate.

Divided table Planer Machine:

A simple divide table planer as shown in the figure.

It consists of two tables on the bed that can reciprocate separately or together. This design saves the idle time while setting work.

This planer is mainly suitable for mass production work where identical machining is to be done, by loading the work on one of the tables, while the other reciprocates past the cutting tool for finishing the work.

After finishing the work the table is stopped and the finished job is removed by shifting the table to the end and reloading the work on this table while the first table holding the job now reciprocates past the tool.

For heavy and large jobs, both the tables are clamped together and are given the reciprocating movement under the tool for machining.

Planer Machine Specification:

A Planer may be specified by the following dimensions:

Distance between two housings
Height from top of the table to the cross rail in its upmost position.
The maximum length of table travel

The open size planer is specified by the largest job that can be machined on its table.

In addition to these basic dimensions, other particulars are:

Number of feeds available
Number of speeds available
Length of bed.
Length of table
Power input
Floor space required
Method of a driving table, geared or hydraulic
Net weight of the machine

Advantages of Planer Machine:

There are some advantages of Planer Machine and those are:

Greater accuracy
Good surface finish
The major advantages are at a time more than one tool can perform on the workpiece
Low maintenance requires comparatively other machine tools

Disadvantages of Planer Machine:

These are some disadvantages of Planer Machine:

The machine price is high
The power consumption is quite more
Skilled worker required
Only tool single point is used. We can not use other than a single-point cutting tool

Application of Planer Machine:

These are the applications of Planer Machine:

Planer machine used for providing flat surfaces on the workpiece
It is also used for cutting angular surfaces

Summary:

What is Planer Machine?

A planer is a machine tool primarily designed to produce planes and flat surfaces by a single-point cutting tool. A planer machine is just like a shaper machine but, it is very large and massive and it is capable of machining heavy jobs which can't be done by the shaper.

What is the difference between a shaper machine and a planer machine?

What are Parts or Component of the Planer Machine?

It consists of the following parts:
1. BED
2. Table or Planten
3. Housing or Column
4. Cross rail
5. Tool head
6. Driving and
7. Feed Mechanism.

What operation can be performed on Planer Machine?

The following Operation that can be performed on Planer Machine:
1. Planing Flat horizontal surfaces
2. Flat vertical surfaces
3. Planing angular surfaces and machining dovetails
4. Curved surfaces
5. Planing slots and grooves.

What are the types of Planer Machine?

There are five different types of Planer Machine:
1. Double housing Planer Machine
2. Open side Planer Machine
3. Pit Planer Machine
4. Edge or Plate Planer machine
5. Divided table Planer Machine

So this is all about the Planer Machine I hope you like my article, Now I want to hear from you, feel free to comment down below your thoughts, I would love to answer those queries.

Till then see you in another article. Cheers!

Reference:

https://en.wikipedia.org/wiki/Machine_tool
https://nptel.ac.in/content/storage2/courses/112105127/pdf/LM-20.pdf