Plastic is any synthetic or semi-synthetic organic polymer. While plastics may be made from just about any organic polymer, most industrial plastic is made from petrochemicals. Thermoplastics and thermo setting polymers are the two types of plastic.
Plastics Processing Methods
Plastic processing technology consists of those factors that affect the outcome in the plastic processing procedures. Plastic processing is the method of transforming the plastic material and/or plastic waste into useful products like toys, bottles, stationery etc. There exists a large array of different processes and techniques used for processing the plastic. Some of them are injection, compression, extrusion or polystyrene expansion etc.
There exist a large array of machines and/or equipments that are used in the plastic processing technology. Some of those are autoclaves, blow molding machines, die cutting machines, extruding machines, injection molding equipment, mold cleaning equipment, plastic compounding equipment, plastic cutters, plastic cutting machines, plastic mold heaters, plastic shredders, spin casting equipment and thermoforming machines.
Few machines equipments used in plastic processing technology
- Blow Molding Machines are used for making products like bottles, containers, packaging items, automotive parts etc.pressure is used to form hollow objects, such as the soda pop bottle or two-gallon milk bottle, in a direct or indirect method. In the direct blow-molding method, a partially shaped, heated plastic form is inserted into a mold. Air is blown into the form, forcing it to expand to the shape of the mold. In the indirect method, a plastic sheet or special shape is heated then clamped between a die and a cover. Air is forced between the plastic and the cover and presses the material into the shape of the die.
- Plastic Injection Molding Machines have been widely used to manufacture a variety of plastic products. Usually plastic injection molding machines are used to manufacture disposable razors, automotive engine components etc.It is the second most widely used process to form plastics. The plastic compound, heated to a semifluid state, is squirted into a mold under great pressure and hardens quickly. The mold then opens and the part is released. This process can be repeated as many times as necessary and is particularly suited to mass production methods. Injection molding is used for a wide variety of plastic products, from small cups and toys to large objects weighing 30 pounds or more.
- Thermo Formers or Vacuum Formers have been extensively used for the manufacturing of products like plastic cups, bed liners, plastic plates, plastics covering, plastic trays, plastics bed pans, plastic bathroom products, plastic containers etc.
- Trim Presses have been immensely used in various applications i.e. for making plastic products.
- Plastic Extrusion Machines or Plastic Extruders are generally prevalent in the manufacturing of products like plastic hoses, plastic sheet, plastic tubing, plastic tape, medical tubing, PVC pipe, plastic straws, flexible tubing, rubber tubing, plastic bags and many more.The main process used to form plastics. A heated plastic compound is forced continuously through a forming die made in the desired shape (like squeezing toothpaste from a tube, it produces a long, usually narrow, continuous product). The formed plastic cools under blown air or in a water bath and hardens on a moving belt. Rods, tubes, pipes, Slinkys, and sheet and thin film (such as food wraps) are extruded then coiled or cut to desired lengths.Plastic fibers also are made by an extrusion process. Liquid resin is squeezed through thousands of tiny holes called spinnerets to produce the fine threads from which plastic fabrics are woven.
- Plastic Granulators are specially used to cut & shred plastics. Its example being recycling plastic, recycle plastic parts, plastic regrind, plastic size reduction, etc.
Types of Plastic
There exist about 50 different types of plastics. Broadly plastics can be classified into two types namely Thermosetting and Thermoplastic. The Thermosetting Plastics are those that cannot be soften again, after being exposed to heat and pressure. On the action of heat and pressure, the molecular chain of thermosetting plastics become cross-linked, due to what it forbids the slippage when pressure& heat are reapplied.
The thermoplastic are those that can be soften again and again & remade by the action of heat and pressure. On the action of heat and pressure, the molecular chain of thermoplastics undergoes change and the polymers slide past each other, that results in the property of plasticity. Some of the different thermoplastic and thermosetting plastics are mentioned below.
- Vinyl Plastics :- Vinyl plastics belong to the thermoplastic group. Vinyl plastics are the sub-polymers of vinyl derivatives. These are used in laminated safety glasses, flexible tubing, molded products etc.
- Polyurethane Plastics :- Polyurethane plastics belong to the group that can be thermosetting or thermoplastic. Polyurethane is the only plastic which can be made in both rigid and flexible foams. The flexible polyurethane foam is used in mattresses, carpets, furniture etc. The rigid polyurethane foam is used in chair shells, mirror frames and many more. Due to the property of high elasticity, some polyurethane plastics are used in decorative and protective coatings. The high elasticity makes these polyurethane plastics resistant to a chemical attack.
- Polyacrylics Plastics :- Polyacrylics belong to the group of thermoplastics. Polyacrylics are transparent and decorative. Polyacrylics plastics can be shaped in any form like the windshields for airplane.
Apart from these, plastics have been also divided into seven different types by the plastic industry. These seven types of plastics are :-
- Polyethylene Terephthalate (PETE) :- PETE is one the most recycled plastic. It finds usage in various bottles like that of soda and cooking oil, etc.
- High Density Polyethylene (HDPE) :- HDPE is generally used in detergent bottles and in milk jugs.
- Polyvinyl Chloride (PVC) :- PVC is commonly used in plastic pipes, furniture, water bottles, liquid detergent jars etc.
- Low Density Polyethylene (LDPE) :- LDPE finds its usage in dry cleaning bags, food storage containers etc.
- Polypropylene (PP) :- PP is commonly used in bottle caps and drinking straws.
- Polystyrene (PS) :- PS is used in cups, plastic tableware etc.