Manufacturing is the technique that converts the raw materials into finished goods through some continuous processes which involve special knowledge, manpower, equipment and machinery. Modern day manufacturing is not possible without having a good knowledge of these processes. A complete man-machine setup with the division of labour is involved in these processes. Almost any raw material can be converted into finished goods by means of these significant manufacturing processes. Modern day manufacturing is not possible without these processes –
- Machining and
- Imaging and Coating
- Additive manufacturing
Different Types of Casting Processes Explained
Casting is a process of manufacturing in which molten metal is poured into the mould having the cavity of the desired shape. After the metal solidifies the total solid metal is taken out of the mould. This solid part is called the cast part or the casting. The final product is machined if necessary otherwise used as it is. With casting, you can make any finished goods of any shape. Different casting processes involve sand casting, die casting, centrifugal casting and lost wax casting. Each of the casting processes has their merits and limitation. Let’s discuss the different casting techniques.
Materials of any melting point can be cast in the sand casting process. It is very cheap but to get desired finishing extra care should be taken. A typical sand casting process involves a furnace to melt the metal, the pattern and the sand mould. Generally, green sand with some natural binders is used to make the sand mould. Any kind of porosity in the sand should be removed. Proper ramming of the sand is necessary. The sand and the binder ratio should be accurate. Different types of sands are available for casting. Suitable sand selection is also a very important task in the process.
Advantages of Sand Casting
- It is very cost efficient
- Metals or alloys of any melting point can be used.
- Any shape can be obtained.
- Very less wear and tear of the pattern. The pattern used is also of very low cost as it is mainly made of wood.
- Ferrous parts can be easily manufactured. Materials of the high melting point can be used.
Disadvantages of Sand Casting
- Extra machining work is required in this process. After the metal solidifies some extra metal needs to be cut by machining process because of the runner and the riser shapes.
- Surface finish is not always up to the mark.
- Dimensional accuracy is difficult to achieve. The parts in which the dimensional accuracy is not that important can be easily manufactured by sand casting.
- Materials may have low mechanical strength due to some faults in the casting technique as the process is totally manual.
Die casting is another casting method that involves permanent die. The die or permanent reusable moulds are used in die casting. As a result, the finished product is geometrically accurate in shape and dimension. It involves high pressure inside the casting chamber so the castings are accurate in size and shape. Mainly non-ferrous metal parts are manufactured in die casting method. Electrical equipment, motor parts, telecommunication materials, automobile parts and many other assembly parts are frequently manufactured using die casting.
Advantages of Die Casting
- Manufacturers can get complex shapes with close tolerances.
- It is suitable for rapid mass production. All the parts will have same dimensions and sizes.
- Very less surface preparation is needed for making the castings.
- The uniform design is one of the great features of die casting.
- High mechanical strength is obtained by die casting
Disadvantages of Die Casting
- It is not suitable for small-scale production. To make the process cost-effective, the mass production of the materials is needed.
- High initial cost of the materials and setup is observed.
- There are some limitations of the dimensions of the finished goods. So goods having any dimensions and shapes are not suitable to manufacture in die casting.
- Materials having lower melting points are only suitable for die casting.
Centrifugal casting is another precision casting process. In centrifugal casting, the molten material/metal is poured into the spinning chamber. The chamber orientation can be vertical or horizontal. It depends on the size and shape of the product needed by the manufacturer. If the material is tubular then the horizontally rotating chamber is used. When ring-shaped materials are needed as the finished goods vertical chambers are used. Centrifugal castings are used for that parts that can symmetrically rotate on the same axis. For more knowledge about Centrifugal casting please visit the link:
Advantages of Centrifugal Casting
- Excellent surface finish for the round shafts, tubes, cylinder and ring-shaped materials.
- Excellent mechanical strength due to the fine-grained structure of the materials.
- High production rates.
- Hollow interiors in the products like tubes and rings can be done easily without the application of the core.
- Lighter impurities.
Disadvantages of Centrifugal Casting
- Not all metals are suitable for centrifugal casting.
- The initial setup cost can be higher.
Lost Wax Method or investment casting
In investment or lost wax casting the molten metal is poured into the mould that is made of wax. It is also called the lost wax method. The wax patterns are prepared by injection moulding. The outer part is made of a harder shell. When the molten metal is poured, the wax is melted and drained away. The metal sample solidifies and finished good is obtained. Aerospace industries, computer parts manufacturers, food and beverage makers as well as jewellers are using lost wax methods.
- Superb intricate designs can be obtained.
- Excellent surface finish is obtained and no parting line is present.
- High accuracy can be obtained for the complicated designs.
- Very less machining is required for the finished goods.
- It is a very costly process.
- The parts that can be cast should be of very low weight.
These are some of the major casting processes involved in modern-day manufacturing process. For more knowledge have a look at the casting classifications.