Lectures notes On Manufacturing Science and Technology Prepared by Dr. Punyapriya Mishra Dr. Pragyan Paramita Mohanty Assistant Professor Department of Mechanical Engineering VSSUT, Burla
SUB:- MANUFACTURING SCIENCE & TECHNOLOGY-I Semester - 3rd (Mechanical Engineering)
Module-I Introduction Improved civilization is due to improved quality of products, proper selection of design as well as manufacturing process from raw materials to finished goods. Classification of manufacturing processes:(a) (b) (c) (d) Casting Forming Fabrication Material Removal Metal Casting Process:Metal Casting is one of the oldest materials shaping methods known. Casting means pouring molten metal into a mould with a cavity of the shape to be made, and allowing it to solidify. When solidified, the desired metal object is taken out from the mould either by breaking the mould or taking the mould apart. The solidified object is called the casting. The process is also called foundry. Advantages: Any intricate shape can be produced. Possible to cast both ferrous and non ferrous materials Tools are very simple and expensive Useful for small lot production Weight reduction in design No directional property Limitations: Accuracy and surface finish are not very good for final application Difficult to remove defects due to presence of moisture Application:Cylindrical bocks, wheels, housings, pipes, bells, pistons, piston rings, machine tool beds etc. Casting terms:Flask- It holds the sand mould intact. It is made up of wood for temporary application and metal for long term use. Drag- Lower moulding flask Cope – Upper moulding flask Cheek – Intermediate moulding flask used in three piece moulding. Pattern - Replica of final object to be made with some modifications. Mould cavity is made with the help of pattern.
Parting line – Dividing line between two moulding flasks. Bottom board – Board used to start mould making (wood) Facing sand - Small amount of carboneous material sprinkled on the inner surface of the mould cavity to give better surface finish to casting. Moulding sand – Freshly prepared refractory material used for making the mould cavity. (Mixture of silica, clay & moisture) Backing sand – used and burnt sand Core – Used for making hollow cavities in the casting Pouring basin – Funnel shaped cavity on the top of the mould into which molten metal is poured Sprue – Passage from pouring basin to the mould cavity. It controls the flow of molten metal into the mould. Figure 1 Cross-section of a sand mould ready for pouring Runner – Passage ways in the parting plane through which molten metal flow is regulated before they reach the mould cavity Gate – Actual entry point through which molten metal enters the mould cavity Chaplet – Used to support the core to take of its own weight to overcome the metallostatic force. Chill – Metallic objects to increase cooling rate of casting Riser – Reservoir of molten metal in the casting so that hot metal can flow back into the mould cavity when there is a reduction in volume of metal due to solidification. Sand mould making procedure:The first step in making mould is to place the pattern on the moulding board. The drag is placed on the board (figure 2 (a)). Dry facing sand is sprinkled over the board and pattern to provide a non sticky