Used Slotting Machines for Sale — 307

A slotter or slotting machine is basically a heavy duty shaping machine in which the cutting tool moves vertically. The ram is mounted on an independent bearing, the upper part of which is pivoted to shift the ram in any angular position. The job is generally supported on a round table that has a rotary feed in addition to the usual table movements in cross-directions. Thus the work table can be given transverse, longitudinal or rotary movement. A slotting machine works on the same principle as an ordinary shaper except that the ram which carries the tool moves in the vertical direction at right angles to the work piece. Slotters are commonly used for internal machining of blind holes, key ways, recesses and also for the cutting of internal and external teeth on large gears.

Shaping vs. Slotting

The chief difference between a shaper and a slotter is the direction of the cutting action. The cutting tool moves vertically up and down while performing the cutting operation as against the horizontal to and fro motion in a shaper. Also the depth of cut is adjusted by moving the cutting tool horizontally in a slotter machine whereas vertical movement of the tool in a shaper is responsible for determining the depth of cut. Slotting machines are characterized by longer stroke length than shaping machines. They are also less strong and rigid comparatively. And slotting machines are used mostly for machining internal surfaces while shapers are predominantly used for machining flat surfaces.

Specification of a Slotter

Slotters are generally specified in terms of the maximum length of a stroke. A little consideration will show that the size of the job that can be machined will be less than this size by an amount equal to the top and bottom clearances of the tool. The ram stroke of a slotter for sale ranges from 300 to 1800 mm. Longitudinal & transverse feeds range from 0.05 to 2.5 mm/stroke. There is also a possibility of tilting the ram up to 15 degrees on both the sides from vertical permitting the machining of dies with relief. Ram speeds usually vary from 2 to 40m/min. The other common specifications of a slotting machine are: Work table diameter (mm), Transverse movement of the table (mm), Longitudinal movement of the table (mm), Motor Power (KW), Maximum distance between tool post to bed (mm) and Maximum distance between ram guide and work table (mm).

Slotting Drive

In a slotting machine, the cutting action is performed during downward stroke. The mechanism of slotter should be designed in such a way that the ram should move slowly during the cutting stroke and should move fast during the return stroke, thereby the idle time of the machine is reduced. This mechanism is known as Quick return Mechanism. This can be achieved by three means:

• Crank & Slotted Link - Slotted disc mechanism
• Driving wheels & Trunnion - Slotted link and gear mechanism
• Hydraulic Power - Hydraulic mechanism

Cutting speed depends on Stroke length, Number of strokes and Quick return ratio which is the ratio of the duration of forward stroke to the return stroke. Quick return ratio usually varies between 2:1 and the practical limit is 3:2. Some of the advantages of a hydraulically powered slotter over the other mechanisms are:

1. Greater flexibility of speed
2. Smoother in operation
3. Ability to slip in case of overload, thereby eliminating tool and machine damage
4. Possibility of changing speeds and feeds during operation
5. Providing a constant speed all over the stroke.

Types of Slotters

The slotting machines can fall into any of the following three types:

• Puncher Slotter
• Production Slotter
• Tool room Slotter

The puncher slotters are heavy duty machines equipped with powerful motor. As the length of the stroke is very large in these kind of slotter machines, they are commonly used for removing large amount of material from large castings or forgings. Production slotters are used for general production work which does not involve greater precision & accuracy. The third type of slotting machine is lighter and operable at higher speeds. It is of the precision type and used for very accurate machining. If you are looking for a used slotting machine for sale, you can easily find these different types of slotters on TradeMachines,

Application of Slotters

The usual and possible machining applications of slotting machines and slotting machines tools are:

• Internal flat surfaces
• Enlargement and finishing of non-circular holes bounded by a number of flat surfaces
• Blind geometrical holes like hexagonal socket
• Internal grooves and slots of rectangular and curved sections.
• Internal keyways and splines, straight tooth of internal spur gears, internal curved surface of circular section, internal oil grooves etc. which are not possible in shaping machines.

Productivity and process capability of slotting machines are very poor and hence employed mostly for piece production involving maintenance and repair work in small industries. But, slotters are also used in high volume operations like steel rolling mills, paper mills, power plants, ship building, textile factories, tool rooms, and repair shops.

Slotting Machine Manufacturers

Some of the world renowned slotting machine manufacturers are: CAMS, PADE, PARVEAU MAB, HELLER MAQUINA HERRAMIENTA, WMH, MARTIN, GUILLIET and FRÖMAG.