Slotting machines are one of the key reciprocating machine tools known to man. It is also known as a slotter. It is a heavy-duty vertical shaper; that is, it carries a vertical ram that moves in a reciprocating manner for cutting slots in the job. Its difference with the shaper lies in the horizontal structuration of the ram in the latter (shaper).
The job that is mounted on the worktable of the slotting machine is given a slow longitudinal, cross, and rotary feed.
It is used for performing many operations other than slotting, which is its unique machining quality. These operations include machining regular or irregular surfaces, cylindrical surfaces, gear cutting, grooving, and others.
Main Parts of Slotter
The main parts of a basic slotter are described below:
It is commonly known as the bed of a slotting machine. It supports the column, the worktable, and the ram drive mechanism, among many other fittings.
The top of the base is provided with a number of fine-machined guideways for the sliding of the saddle. These guideways run perpendicular to the column of the slotter.
It is also known as the pillar of the machine. It carries the ram drive mechanism. Its front end is very precisely machined into guideways for the reciprocating vertical movement of the ram.
As shown, it is mounted on the base and can slide over its guideways. It moves longitudinally (towards or away from the column) to provide longitudinal feed to the job either by mechanical or manual control.
On the saddle are machined guideways for the cross-slide. These guideways are perpendicular to the guideways of the base.
It is mounted on the saddle’s guideways and may slide towards the face of the machine to supply cross-feed to the job.
It slides vertically, reciprocating on the guideways of the column. It carries the toolhead to which the slotting tool is fixed.
It must be borne in mind that out of the two strokes of the ram, it is only the downward stroke that performs the cutting: the upward stroke of the ram in a slotter is an idle stroke.
Slotter tools have a thicker cross-section because the cutting pressure acts along the whole length of the cutter in the vertical plane. The figure below shows the tool angles in a vertical plane for a slotter cutter.
These are forged tools that are designed to have top rake but not side rake yet side and front clearance. Tools for slotting are thinner at the edge. In the schematic shown above, the round nose tools are used for contoured surfaces and flat nose tools for flat surfaces.
Types of a Slotting Machine
There are many types of a slotter. They are discussed below:
- Puncher slotter
- Precision slotter
- Production slotter
- Key slotter
It is a heavy-duty slotter that is used to remove metal in large quantities from the forging or castings. It is bigger, for instance, up to 1.8 to 2 m.
The ram driving mechanism consists of a spiral pinion entangled with the rack teeth that are cut on the underside of the ram.
The variable speed provides the driving force to the pinion reverse electrical motor akin to that in a planer. Likewise, the drive to the table is also provided by the electrical gears.
It is used for precision cuts; it is a light slotter that operates at high speeds. It uses special jogs for handling a number of identical works required in mass production. It is fitted with a Withwork quick return system.
It is heavier and sturdier in construction and is usually used for tapered jobs.
It is a unique slotter that is custom-designed for machining keys in pulleys, cams, gears, and so forth. The figure below shows a key slotter schematic that does the slotting operation of pulley A on tapered bars B with tool F.
Operations of Slotter
It is used for performing many operations other than slotting, which is its unique machining quality. These operations include machining regular or irregular surfaces, cylindrical surfaces, gear cutting, grooving, and others. The figure below shows a cylindrical job that is subject to key-way cutting.
I am the author of Mechanical Mentor. Graduated in mechanical engineering from University of Engineering and Technology (UET), I currently hold a senior position in one of the largest manufacturers of home appliances in the country: Pak Elektron Limited (PEL).