UNIT-I SLOTTING MACHINES

Slotting machine

Slotting machine is also called as Slotter

Line diagram of slotter CROSS SLIDE SADDLE

Slotters

Slotter A Machine which produces flat surfaces A Ram holding the Tool reciprocates Ram reciprocates in vertical direction Work is fed perpendicular to the tool

Slotter - working principle TOOL B A Cutting Tool repeatedly travels along line A B Work is fed a small distance each time Feed of work & line of tool motion are in same plane but perpendicular

WORKING PRINCIPLE – contd. The tool line eventually reaches position C D Combination of two movements results in the flat plane ABCD being machined B A D C

WORKING PRINCIPLE – contd. Work is supported on a rotary table. Table can have longitudinal and rotary movements Straight and rotary cuts can be produced.

CLASSIFICATION According to design and purpose the slotters are classified into two types Puncher Slotter Precision tool room Slotter Puncher slotter: Intended for removing large amount of metal from heavy works. heavy and rigid machine Ram driven by rack and spiral pinion mechanism used for machining large castings and forgings

Production slotter

Precision tool room slotter: Used for tool room work, where accuracy important Lighter in construction Fitted with quick return mechanism Operates at high speeds and designed for light cuts Gives accurate finish Suitable for small to medium size work pieces

Difference between vertical shaper and Slotter in vertical shaper the tool holding ram can tilt by about 100 with respect to vertical axis In slotter ram cannot tilt at all. In all other aspects vertical shaper and slotter are similar

Slotting machine Introduction Having known the Working Principle we will now look at : The Constructional Details of a slotting Machine Function of each part Specifications of a slotter M305.30

Slotting machine -construction RAM COLUMN TOOL HEAD T-SLOTS CIRCULAR TABLE CROSS SLIDE SADDLE BASE M305.30

Slotting machine M305.30

Line diagram of slotter

Main parts of a slotter 1. Base 5. Cross slide 2. Column 6. Saddle 3. Ram 7. Tool head 4. Table

Parts - functions 1. Base Bottom most part Supports other parts of the machine Acts as a reservoir of lubricating oil Made of Cast Iron Contd..

Base Rigidly built to take up cutting forces Top of bed is accurately finished Guide ways are provided for saddle Guide ways are perpendicular to column face

Column Vertically mounted on the base Houses Driving Mechanism of Ram Has guide ways on which Ram slides Made of Cast Iron Also houses feeding mechanism COLUMN

Ram Reciprocating vertically up and down of a slotter Mounted on guide ways of column It carries Tool Head / cutting tool Connected to Driving Mechanism An arrangement is provided on the body of ram to change length of stroke R A M M305.30

Table It holds the work piece. A circular casting with T-slots on its top Movement of table can be linear or rotary Table is graduated in degrees so indexing can be done Slotter vice may be fitted in the T-slots Work may be fixed in the vice Operated manually or by power TABLE

Saddle It is mounted on guide ways of bed It can be moved towards or away from bed Using saddle longitudinal feed is given Top is accurately finished to provide guide ways for cross slide These guide ways are perpendicular to the guide on the base Operated either manually or by power

Cross slide Circular work-table is mounted on the top. Mounted on guide ways of saddle Moves parallel to the face of the column Using cross slide cross feed is given Operated either manually or by power

Tool head It is attached to the bottom end of Ram Carries Tool post on it Tool is fixed in position No swiveling along verticle axis or horizontal axis

Specifications of Slotting machine Max. length of Ram Stroke Diameter of work table in mm. Type of Drive Maximum table travel. Power input Floor Space required

Specification

Slotter driving mechanism A Slotting machine produces flat surfaces The Ram holding the Tool reciprocates vertically up and down Cuts the material only in down stroke There should be some mechanism to move the ram in reciprocating motion It is called as slotter driving mechanism The mechanism commonly used is slotted disc mechanism

Slotted disc mechanism

Quick return mechanism (QRM) A Mechanism makes the ram to move slowly during cutting stroke. During return stroke ram moves at a faster rate. To reduce the idle time,It Should return quickly . The mechanism adopted is known as QRM

Methods to obtain Q.R.M. in slotter 1. Whitworth Q.R.M. Mechanism 2. Variable speed reversible motor drive mechanism 3. Hydraulic drive Mechanism The mechanisms for QRM in slotter are similar to QRM in shaper

Feed in Slotter In Slotter feed is given by table Feed movement is intermittent Feed is given at the beginning of the cutting stroke Feed may be given either manually or by power Table will have three types of feed movements a. longitudinal b. cross and c. circular feeds. Contd…

Types of feed in Slotter Longitudinal feed: Table is fed perpendicular to the column Table moves towards or away from the column Cross feed: Table is fed parallel to the face of the column Circular feed: table is rotated with respect to verticle axis

Feed mechanism of a Slotter Feed shaft

Feed mechanism of a Slotter Uses a ratchet and pawl mechanism Feed shaft engaged with cross, longitudinal / rotary feed screws has the ratchet mounted on it. Ratchet is moved by small amount in one direction only with the help of a connecting rod, lever. The roller moves in the cam groove cut on the face of the bull gear of slotting machine.

Operations on slotter 1. Machining flat surfaces 2. Machining Circular Surfaces 3. Machining internal surfaces 4. Machining grooves or key ways

Setup for Machining Work is properly held in a vice Table is raised to a gap of 25 to 30 mm between tool & work The length & position of stroke are adjusted The length of stroke should be nearly 20 mm longer than the work Contd…

Setup for Machining The approach & over run should be 10 & 5 mm respectively. Depth of cut is adjusted by rotating down the feed screw of tool head Feed is adjusted about half the width of cutting edge of tool

Machining Flat Surfaces Fix the work properly on the table Adjust the length of stroke Set the required cutting speed Give required feed of the table Tool is held in the tool head of ram Ram reciprocates up and down

Machining Flat Surfaces Feed has to be given at the beginning of cutting stroke Both internal and external surfaces can be machined Give suitable depth of cut for rough cuts Finishing the job by giving less depth of cut

Machining flat surfaces

Machining circular surfaces Tool is set radially on the work Work piece is placed centrally on the rotary table Feed is given by the rotary table feed screw Feed screw rotates the table through an arc Adjust the length of stroke Set the required cutting speed Finishing the job by giving less depth of cut

Machining internal surfaces Fix up a tool in tool post Cross, longitudinal and rotary feed are combined Any contoured surface can be machined Mostly done manually Good skill is required from operator

Machining grooves or key ways Slotter is specially intended for cutting internal grooves External or internal gear teeth can be machined Fix up the job between two centers Cut first a key way Move / Rotate work by the required amount Indexing can be done by using graduations on rotary table

Cutting Key ways Fix up the job between two centres Cut first spline similar to a key way Move / Rotate work by the required amount Use index plate for this purpose

Cutting Key ways