Plastic Moulding Presented By Bidve M A A
Plastic Moulding Presented By, Bidve M. A.
• A plastic can be defined as any nonmetallic material that can be moulded into any desired shape. • Plastics are synthetically produced non metallic compounds. • They can be moulded into various forms and hardened for commercial use.
Properties of Plastics These are versatile(Easily form in any shape) They are relatively inexpensive. They have high strength to weight ratio. Good insulation properties, thermal as well as electrical. • Good corrosion resistance. • Lightweight and flexible. • Better resistance to moisture. • •
Thermoplastic It is defined as a material which soften on application of heat and can be set into desired shape on cooling. They can be remelted again and again on successive application of heat. These plastics are processed by injection moulding, blow moulding, extrusion moulding, etc.
Examples • Polyethylene: Packaging, electrical insulation, milk & water bottles. • Polypropylene: Carpet fibers, automotive bumpers, microwave containers. • PVC: Electrical cable, floor and wall covering, credit card. • Polystyrene: Disposable spoons, soft packaging material.
Examples • PMMA Polymethyl methacrylate (Acrylics): Paints • Polyamide(Nylon): Textiles & Fabrics, gears, bushing and washers, bearings. • PET Polyethylene terephthalate: Bottles for acidic foods like juices, food trays. • PTFE Polytetrafluoroethylene: Non stick coating, raincoats, dental floss.
Thermosetting • It is defined as a material which become soft on application of heat and become hard by chemical change are known as thermosetting plastics. • They can not be softened again by application of heat. • Compression moulding and transfer moulding are methods to process these plastics.
Example • Polyurethanes: Mattress, cushion, insulations, toys. • Silicon: Surgical gloves, oxygen masks • Melamine, Epoxie resins and polysters.
Plastic Moulding • There are no of methods are used for processing of plastics. 1. Type of plastics 2. Softening temperature. 3. Geometry 4. Size of finished product.
Plastic Moulding Methods • • • Compression Moulding. Injection Moulding. Blow Moulding. Vaccum Forming. Extrusion. Calendering.
Compression Moulding • It is similar to closed die forging, Thermosetting Plastics are formed by this process. • In this process premeasured quantity of plastics is put in a heated mould and compressed under suitable temperature and pressure.
Injection Moulding • Injection moulding machines were made in 1930. These can be used to mass produce toys, kitchen utensils, bottle caps, cell phone. • In this process melted plastic is forced into a mould cavity. • This process is used in mass production.
Blow Moulding • A little bit hot soft plastic is squeezed into the end of a mould. • Compressed air is used to blow a big bubble until it fills up the whole mould. • Bottles, toys, money boxes are made
Extrusion Moulding • The process consist of feeding the powered plastic from the hopper into the heated chamber. • A rotating screw carries this material forward and forces it out through the heated orifice of the die. • The orifice carries the shape corresponding to the shape of the final product.
Vaccum Forming • It is also known as thermo forming. • A sheet of plastic is clamped in a frame and heated until it is stretchy. Then it is suck into a mould. • Inside body of refrigerator, Hand basin
Calendaring • It is important method for making of films and sheets. • Calendaring is the finishing process applied to textiles and paper. • Rolls of the material are pressed between several pairs of heated rollers to give a shiny surface.
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