The die is most important part in die casting machine which will be discussed here in detail. Dies for all the machines are similar in construction as there is little difference in the method of holding and operating them. Generally it is made into two halves so that the casting can be easily removed from it after solidification. One part [...]
In this article we will discuss about the process and moulds of centrifugal casting. Process of Centrifugal Casting: i. True Centrifugal Casting: In this process, the castings are made in a hollow, cylindrical mould rotated about an axis common to both casting and mould; the axis may be horizontal, vertical or inclined. Usually the mould is rotated in horizontal plane. [...]
In this article we will discuss about:- 1. Meaning of Shell Moulding 2. Patterns and Materials for Making Shell Mould 3. Process 4. Merits 5. Demerits. Meaning of Shell Moulding: Shell moulding is a recent invention in casting techniques for mass production and smooth finish. It was originated in Germany during Second World War. For some time, it was called [...]
The following points highlight the five main types of resistance welding. The types are: 1. Spot Welding 2. Projection Welding 3. Seam Welding 4. Butt Welding 5. Percussion Welding. Type # 1. Spot Welding: This is probably the simplest form of resistance welding and best suited for ordinary sheet steel. For obtaining good welds having strength, and to avoid the [...]
In oxyacetylene welding, the two gases used for producing flame are oxygen and acetylene. Oxygen is used to support and intensify combustion. It is generally prepared in factories by liquefying air and then separating it into its component parts by rectification. From factories, it can be obtained under high pressure in cylinders which are fitted with pressure regulators to get [...]
The following points highlight the equipments used for oxyacetylene welding. The equipments are: 1. Welding Torch 2. Pressure Regulator 3. Hose and Fittings 4. Cylinders 5. Goggles 6. Spark Lighter 7. Apron 8. Gloves 9. Welding Rods 10. Fluxes. Equipment # 1. Welding Torch: It is a tool for mixing the two gases in the desired volumes and burning the [...]
The current and voltage requirements during arc welding process vary considerably. In arc welding, short circuits keep on taking place frequently. For example, whenever the operator touches the electrode to the work in order to strike an arc, short circuit is created. Similarly when the molten globules of weld metal cross the arc, electric short circuits (around 20 nos. per [...]
In this article we will discuss about:- 1. Purpose of Electro-Discharge Machining (EDM) 2. Machining Accuracy in EDM Process 3. Automation 4. Orbiting Control Facility 5. Advantages 6. Disadvantages 7. Applications. Purpose of Electro-Discharge Machining (EDM): In electrical machining processes, electrical energy is used directly to cut the material to final shape and size. Efforts are made to utilise whole [...]
In this article we will discuss about:- 1. Meaning of Wire-Cut EDM 2. Features of Wire-Cut EDM 3. Spark Machining. Meaning of Wire-Cut EDM: The wire-cut EDM uses a very thin wire 0.02 to 0.3 mm in diameter as an electrode and machines a workpiece with electrical discharge like a bandsaw by moving either the workpiece or wire. Erosion of [...]
The typical ECM machine consists of a table for mounting the workpiece. The tool is mounted on a quill fixed on a ram. Vertical box frame structure has excellent rigidity required and is best suited for precision work. Vertical C-frame structure has less rigidity but offers greater accessibility to the workpiece and tooling. The machine base, worktable and all other [...]