What is Slotting Machine?- Definition, Parts, And Types

What is Slotting Machine?

Slotting machines are reciprocating machines primarily employed to produce horizontal, vertical, or flat surfaces. Their main applications include cutting planes, shaping surfaces, and creating keyways. These machines are particularly well-suited for single-piece or small batch production runs.

A slotter machine is a type of machine tool designed to remove unwanted material from a workpiece by cutting splines, grooves, and other features. The distinguishing characteristic of a slotter is that its ram, to which the cutting tool is attached, moves in a reciprocating vertical motion. This contrasts with a shaper machine, where the ram moves horizontally.

Slotting machines share many similarities with vertical shaper machines, to the extent that slotters can be regarded as a variant of vertical shapers. The slotting machine is a longstanding tool, historically attributed to the inventor Brunel. It typically uses a single-point cutting tool made of high-speed steel.

These machines are versatile, capable of cutting grooves, keys, and slots of varying shapes, as well as producing both regular and irregular surfaces. They are effective for both internal and external machining tasks, including cutting gears and complex profiles. Overall, slotting machines are ideal for operations where vertical tool movement is essential and provides a distinct advantage.

Working Principle of Slotting Machine

The operation of a slotting machine closely resembles that of a shaper machine; however, the primary distinction lies in their orientation. The shaper machine operates with a horizontal motion, whereas the slotting machine functions vertically.

In the slotting machine, the ram is connected to a crank, which, in turn, is linked to a set of gears. When the speed of these gears is increased or decreased, the rotational speed of the crank correspondingly changes. This motion causes the ram to move vertically, alternating between upward and downward strokes.

To begin the machining process, the workpiece is secured to the worktable. The ram is then manually positioned close to the workpiece, and the worktable is adjusted to align with the ram before being firmly clamped. Once power is supplied, the crank rotates at a speed determined by the gear settings, driving the ram’s vertical movement.

The cutting action occurs during the downward stroke of the ram, while no cutting takes place during its upward, or return, stroke. For cutting the workpiece into multiple sections, the operator manually advances the workpiece along the table as needed, allowing the machine to perform the cuts accordingly.

Parts of Slotting Machine

A slotter machine consists of the following different parts:

• Base
• Column
• Saddle
• Cross-slide
• Rotating or Circular table
• Ram and tool head
• Ram drive
• Feed drive mechanism

• Base: The base is constructed with rigidity to withstand all cutting forces as well as the overall weight of the machine. The top surface of the bed is precisely finished to provide guideways for mounting the saddle. These guideways are oriented perpendicular to the face of the column. Typically, the base is made from cast iron.
• Saddle: The saddle rests on these guideways and can be moved either toward or away from the column. This movement can be controlled manually or powered, allowing for longitudinal feeding.
• Cross-Slide: Mounted on the guideways of the saddle, the cross-slide moves parallel to the column’s face, enabling precise adjustments in that direction.
• Ram and Tool Head: The ram slides along guideways located on the front vertical face of the column. It features a slot to adjust the stroke position. At the lower end of the tool head attached to the ram, the cutting tool is secured.
• Ram Drive: This mechanism converts the motor’s rotary motion into the ram’s vertical reciprocating motion. It also allows for different speeds: a slower feed during the cutting (forward) stroke and a faster return stroke, reducing idle time.
• Column: The column is the rigid vertical part integrated with the base on the right side. It houses the ram’s driving mechanism, which moves along its front vertical face, as well as the feeding mechanism for the table.
• Circular Table (Rotating Table): Positioned on the cross-slide, the circular table can rotate to enable circular feeding of the workpiece. It can hold workpieces using clamps, fixtures, or a vice. The table’s rotation can be powered or manual. On some machines, the table is graduated in degrees to allow indexing.
• Feed Drive: This system controls the longitudinal and cross feed of the table, either by power or manually. It also manages the table’s circular or rotary feed around a vertical axis. Intermittent feeding is applied at the start of each cutting or forward stroke of the ram.

Types of Slotting Machine

Different types of slotting machines are:

• Puncher Slotting machine
• Toolroom Sloting machine
• Production Sloting machine
• Keyseater Slotting machine

1. Puncher Slotting Machine

The puncher slotter is a robust and heavy-duty machine specifically engineered to remove a significant portion of metal from castings and forgings. Its stroke length is notably extensive, ranging between 1,800 and 2,000 millimeters.

Typically, the ram of the puncher slotter is driven by the engagement of a spiral pinion with a rack featuring cut teeth located on the underside of the ram. This pinion is powered by a reversible electric motor with adjustable speed, a mechanism that closely resembles that of a planer. The machine’s feed is regulated by electric gears, allowing for precise control.

2. Toolroom Slotting Machine

This machine is lightweight and designed to operate at high speeds. It is intended for highly precise machining, allowing for light cutting and delivering accurate finishes.

Its capability to function at elevated speeds, combined with specialized jigs, enables it to perform a range of tasks efficiently in a production setting.

3. Production Slotting Machine

The production slotter is a robust machine designed for heavy-duty tasks, featuring a substantial cast base and frame, typically constructed in two parts. It is primarily employed for general production purposes.

The ram’s reciprocating motion is driven by a slotted disc connected to a rod. Additionally, a flywheel is incorporated to ensure smooth operation by preventing abrupt stops at the end of each stroke.

4. Key seater Slotting machine

The key seater slotter, also known as a key seating machine, is a specialized type of slotter specifically designed for cutting keyways.

This machine resembles a vertical shaper, with the main difference being the direction from which the cutting tool engages the workpiece. In a key seater, the tool approaches the workpiece from the bottom and performs the cutting action during the downward stroke. Conversely, in a vertical shaper, the tool enters from the top and cuts downward.

Mechanism of Slotting Machine

• Hydraulic Drive
• Variable Speed Motor Drive

Hydraulic Drive:

A speed motor drives a hydraulic pump that supplies oil at a constant pressure through the system. A regulating valve alternately directs this pressurized oil to either side of the piston. Simultaneously, oil from the opposite side of the piston is released back to the reservoir.

The piston, connected to the piston rod and ram, is propelled forward by the oil pressure, causing the ram to advance and carry the attached tool. The alternating flow of oil to each side of the piston is controlled by travel dogs and pilot valves.

When the ram completes its forward and return strokes, a trip dog pilot activates the valve, which in turn adjusts the regulating valve.

This causes the oil supply to switch sides, reversing the ram’s direction. The stroke length of the ram is determined by the position of the trip dogs, which can be adjusted to vary the stroke as needed.

Variable Speed Motor Drive:

In this type of slotter, the speed is achieved by various gears present in the gearbox and the shaft rotates with the help of an electric motor. Originally, it is used in modern large slotting machines.

Specification of Slotting Machines

The specifications of Slotting Machines depend on several factors some of these are:

• Power Input
• Type of drive
• Maximum table drive
• Number of feeds
• Table feed
• Floor space required
• The maximum length of ram stroke
• Number of speeds
• The diameter of the Work Table in MM
• kW of motor

Application of Slotting Machine

The main applications of slotting machines are

• This tool is utilized for cutting keys, slots, metal sheets, and grooves of various shapes, as well as for shaping both regular and irregular forms. It finds application across many manufacturing settings and is especially valuable in workshops where vertical tool movement is essential for producing diverse metal components.
• It is suitable for performing light cuts, creating splines, machining inside keyways, shaping the straight edges of internal spur gears, working on the curved faces of circular sections, internal oil grooves, and similar features.
• It also serves to machine internal recesses on circular, concave, and convex surfaces.
• Additionally, this tool is employed in the machining of both internal and external gears.
• It facilitates the enlargement and finishing of noncircular holes that are defined by multiple flat surfaces.
• It is capable of creating internal grooves and slots with rectangular shapes that include curved sections.
• The tool is effective in internal machining of blind geometric holes, such as those resembling hexagonal sockets.
• Finally, it is used for machining internal flat surfaces.

Advantages of Slotting Machines

The advantages of Slotting Machines are:

• This is a light machine.
• Low-cost machine.
• Low Maintenance.
• Accurate surface finish.
• The tool uses here is a single-point cutting tool.
• Machine efficiency is more.

Disadvantages of Slotting Machines

The disadvantages of Slotter Machines are:

• Skilled worker requires to operate.
• Rigid in construction.

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