Thermosets and Thermoplasctics. A brief description of these two classes will be discussed here.
- Thermosets are the kind of plastics which are not recyclable. They undergo a kind of chemical change at the time of heating. As a result they can be shaped once because of this permanent chemical change. This process is known as heat hardening. They are also known as thermosetting plastics. Examples : Epoxy Resin, Melamine formaldehyde , polyester resin , Urea formaldehyde.
- Thermoplastics are the recyclable types. While heating they undergo a temporary chemical change. After the heat is removed they retain their original shape. The process is known as heat softening. Examples : Polyamide (Nylon), Polymethyl methacrylate, polypropelene, polystyrene, Low density Polythene (LDPE), High density Polythene (HDPE).
Different Manufacturing Processes for Plastics
- thermal forming
- solid-phase forming
The injection molding, Blow molding, Extrusion as well as calendering uses thermoplastics for fabrication. High Pressure Lamination, Compression Molding and reaction injection method uses thermosets
Advantages and Disadvantages of using Plastics
- Plastic is very light in weight.
- It has high strength to weight ratio.
- Complex parts can be easily manufactured.
- Plastics can be of variety of colors or can be clear.
- It is free from corrosion.
- It can work as a electrical as well as thermal insulator.
- It can damp the vibration.
- Creeping can be problem.
- It cannot withstand extreme heat. So it is thermally unstable.
- It can be UV light sensitive.
- The stiffness is relatively low in comparison to other tough materials.
- It has a low strength.
- Reworking or repairing of plastic is very tough.
- Recycling of plastic is a hard job.
Please Read :
- A complete guide to casting patterns
- Sand Casting
- Die Casting
- Centrifugal casting
- Basic Steps of Sand casting
- Different types of pattern materials
- Complete guide of pattern allowances in casting process
- Different types of casting defects
- Properties of various natural and synthetic molding sands
- Different types of molding sand