Slotting machine operation

There is a different operation performed on the slotting machine because this operation is more economical for certain types of work. 

Let us see the different operation performed on the slotter machine :

  • Machining internal and external flat surfaces.
  • Internal recess of circular, semi-circular, concave and convex surfaces.
  • Machining internal and external circular surfaces.
  • Internal machining of blind holes.
  • For shaping internal and external forms or profiles.
  • Machining vertical, angular or inclined surfaces.
  • Machining irregular surface which is difficult to produce.
  • For machining dies and punches.
  • To cut slots, grooves, splines and keyways for both internal and external surfaces.
  • Machining internal and external gear teeth. 

Slotting machine parts

In this article you can see some different parts of a slotting machine which are following below :
  • Base 
  • Column 
  • Saddle 
  • Cross-slide 
  • Rotating table 
  • Ram and tool head assembly 
  • Ram drive mechanism 
  • Feed mechanism 
Now we can see parts in details :

Slotting machine
Base or bed :

The base is rigidly built to take up all the cutting forces and the entire load of the machine. 

It is the key parts of the machine that made from cast iron. 

The top of the bed is accurately finished to provide guideways on which the saddle is mounted. The guideways are perpendicular to the column face. 

Column : 

The column is the vertical member which is made up of cast iron. 

The column is assembled with the base and houses driving mechanism of the ram and feeding mechanism. 

The vertical front face of the column is accurately finished for providing ways in which the ram reciprocates up and down. 

Saddle :

The saddle is mounted upon the guideways and may be moved towards or away from the column either by power or manual control to supply longitudinal feed to the work. 

The top face of the saddle is accurately finished to provide guidance for the cross-slide. These guideways are perpendicular to the guideways on the base. 

Cross-slide : 

The cross slide is mounted upon the guideways of the saddle and maybe moved parallel to the base of the column.

The movement of the slide may be controlled either by hand or power to supply crossfeed. 

The circular worktable is mounted on the top of the cross-slide.  

Handwheels :

It is provided for rotating the table for the longitudinal and cross traverse.

Rotary table : 

The rotary table is a circular table which is mounted on the top of the cross slide. 

The table may be rotated by rotating a worm which meshes with a worm gear connected to the underside of the table. 

The rotation of the table may be affected either by hand or power. 

The rotary table enables a circular or contoured surface to be generated on the work piece. 

Ram and tool head assembly : 

The run is a reciprocating member of the machine mounted on the guideways of the column. 

It supports the tools at its bottom end on a tool head. 

A Slot is cut on the body of the ram for changing the position of the stock. 

In some mechanism, a special type of tool holders is provided to relieve the tool during the return stroke. 

Ram drive mechanism : 

A slotter removes metal during downward cutting stroke only whereas during upward return stroke no metal is removed. 

The usual types of ram drive mechanisms are :
  • Whitworth quick return mechanism
  • Variable speed reversible motor drive mechanism
  • Hydraulic drive mechanism 

Types of slotting machine

There are mainly two types of slotting machine :
  • Puncher slotter
  • Precision slotter 
Puncher slotter :

It is a heavy, rigid machine designed for removal of a large amount of metal from large forging or casting. 

The length of puncher slotter is large it may be as long as 1800 to 2000 mm. 

In this machine puncher slotter, ram is usually driven by a spiral pinion meshing with the rack teeth cut on the underside of ram. The pinion is driven by a variable speed reversible electric motor similar to that of a planer. 

In this machine, feed is also controlled by electrical gear. 

Precision slotter :

It is a lighter machine and is operated at high speeds.

This machine is designed to take light cuts giving an accurate finish. 

By using special jigs, the machine can handle a number of identical works on a production basis. 

This machine is also used for general-purpose work and is usually fitted with a whitworth quick return mechanism. 

Advantages and disadvantages of friction welding

Friction welding works on the basic principle of friction is used to generate heat at the interference surface this heat is used to join two workpieces by applying external pressure at the surface of the workpiece. The joint is created in this welding is due to thermomechanical treatment. The main advantage of friction welding is the ease with which the joining can take place. Now, let us have a deep insight into the pros and cons of friction welding. 

Advantages of friction welding :

  • Oxides and contaminants present would easily be removed during the initial rubbing so that edge cleaning is not a problem.
  • Since the joining takes place by diffusion rather than by actual melting, even dissimilar metals can be joined. 
  • The heat generated is small and below the melting temperature, there will be no distortion and warping.
  • The quality of weld achieved is very high.
  • High welding speed.
  • Economical in other welding operation.
  • No skilled operator is required to work on the friction welding machine since it is completely automatic in operation.
  • No possibility of porosity and slag inclusion.
  • It is an environmentally friendly process since there is no fumes, gases or smoke is generated.
  • No flux, filler metal or gas is required to perform this process.
  • No special power supply is required.
  • Wide variety of metal can be weld by this process.

Disadvantages of friction welding : 

  • This process used for only round bars of the same cross-section. 
  • Limited to angular and flat butt joints. 
  • Set-up cost is very high. 
  • Preparation of workpiece is difficult. 
  • Non-forgeable materiel can not be weld.
  • It can only be used for smaller parts of machines, big parts are not compatible with it. 

Advantages and disadvantages of projection welding

Projection welding is also called as resistance welding produces coalescence of welding material, the heat generated from electric resistance to current through the workpiece hold together with pressure applied to electrodes. Let us have a deep insight into the pros and cons of projection welding in this article. 

Advantages of projection welding :

  • It is possible to weld more than one spot at a given time. The number of welds depends on the number of projections that can come under the tip of the electrode. Up to about 6 welds per cycle can be made which substantially reduces the cost of manufacture.
  • The welds may be placed closer than possible in spot welding.
  • Because of the large-sized electrodes used, their life is much longer than that of the spot welding electrode. The larger contact area makes for very limited deformation of the welding tip.
  • They can help in holding the workpieces together in proper alignment during the welding process.
  • Proper heat balance can be easily obtained in projection welding by making the projections in thicker plates while welding sheets of different thickness. 
  • For welding dissimilar metals, the projections are to be made on the material having higher electrical conductivity to provide proper heat balance.
  • The uniformity and appearance of the weld are much better compared to spot welding.

Disadvantages of projection welding :

  • Prior operation of embossing is required before welding.
  • Electrodes are often to be specially made for a particular operation. This can only be justified when production rates and volumes are large. 

Atomic hydrogen welding

Introduction :

Atomic hydrogen welding is an arc welding process. In this process the arc used in between two tungsten electrodes in a shielding atmosphere of hydrogen. This process was invented by Irving Langmuir in the course of his studies of atomic hydrogen. When Hydrogen is in its atomic state, is a strong reducing gas which prevents oxidation of weld metal and rapid burning of electrodes. Any oxygen present in the surrounding combines with hydrogen forming water which is converted into steam.

Equipment set up :

Set up of this operation consist of hydrogen cylinder, an AC welding machine and the welding torch to accommodate to tungsten electrons, with provision for changing the distance between them. The normal voltage range of the power supply is between 50 to 75 volt with the current varying from 15 to 150 A. This measure is good enough for an electrode size of 1 to 5 mm.

Atomic hydrogen welding

The path of electron travel between the two electrodes is not a straight path as in other arc welding process. Instead, they travel in the form of a fan. This is because the hydrogen atoms formed by the arc causes a downward force because of with electron flow slightly deviates. This fan shape can be changed by altering the distance between the electrodes and the current level. The DC machines could also be used in atomic hydrogen welding, but because of the electron flow is only in one direction, the wear of electron is particularly high and as a result, only AC power supply is used.

When hydrogen atoms recombine near the workpiece surface, they generate a temperature of the order of the 300 0C. Because of this heat, the molten metal becomes highly fluid and therefore, atomic hydrogen welding is used for the flat position only. Filler metal when needed is melted intermittently in the arc fan for fusing with the base metal.

Working principle :

Atomic hydrogen welding the atomic hydrogen welding is an inert gas welding arc welding process done with non-consumable electrodes. The main difference between tungsten inert gas welding and this process is that in atomic hydrogen welding, the arc is obtained between the two tungsten electrodes rather than between the tungsten electrode and the workpiece. This shielding gas used here is hydrogen, which is reactive in nature compared to argon. The hydrogen molecule (H2), when passing through the electric arc, get this dissociated into two hydrogen atoms (H+). The hydrogen atoms are highly reactive. They form hydrogen molecule and combine with oxygen if present to form water vapour enters release intense heat for the necessary melting of the joint. Because of its type reactivity, the atomic hydrogen is able to break the oxide on the base metal and thus allow the formation of a clean weld. 

Application :

When properly performed, atomic hydrogen welding gives an extremely clean weld with excellent quality. It is generally used for welding of tool Steels containing tungsten, Nickel and Molybdenum as also for hard surfacing and repairing of moulds, dies and tools. Though it can be used for any job, its high cost prohibits its general usage.

Oxy hydrogen welding

Working principle :

In oxy-hydrogen welding, hydrogen combines with oxygen to generate steam and attains a flame temperature of around 28000C. But the weld pool is not protected from the atmosphere when the oxygen for combustion is completely provided by the torch itself. So, Oxygen is an amount slightly less than that required for complete combustion is provided by the torch, whereas atmospheric oxygen accounts for the burning of the remaining hydrogen. This gives rise to a protective preheating flame that surrounds the main flame. But this reduces the flame temperature to some extent. Because of the lower flame temperature, oxy-hydrogen welding is a generally slow process. It is normally used to weld thin sheets of steels and alloys with low melting temperatures.

Oxy hydrogen welding

Key features :

  • Operation is convenient & safe
Oxy hydrogen generator produces oxygen and hydrogen gas that you required and also no gas cylinder is required. There is no risk of explosion.

  • Environmental friendly 
In this process, fuel comes from water and there is water vapour after finishing this process so this process is environmentally friendly.

  • Welding features 

Welding work is fast, precision, smooth and beautiful welding spot. The oxyhydrogen flame is concentrated up to 2800 0C so it can heat the welding spot to melting point very quickly.
  • Energy-saving and low cost 
This process is done with very low electricity and pure water. The cost of electricity and water is reduced by more than 40% compared with LPG and other welding processes.