Question

Carry out the equipment and operating procedures between injection molding of thermoplastics and injection molding of thermosets(full detailed answer)

Answer 1

Solution:

Injection Molding: It is a type of manufacturing process used for producing various parts by injecting molten material into a mold. This process can be used for various materials like metals, polymers, ceramics etc. This process mainly consists of two sections. Clamp and the injection unit. Clamping section is similar to the compaction press mostly a hydraulic cylinder is used and the injection unit mainly includes reciprocating screw, barrel etc.

The main difference between the thermosets and thermoplastics are heat resistance and chemical resistance. The other differences in the equipment and operating procedures are shown below:

Injection Molding of thermoplastics: In the production of thermoplastics the main process is the plastic material is melted and injected into a mold under high pressure to create the product and after it is cooled and removed from the mold. The injection tools used for this process are manufacturing according to a specific process. The cost of the mold depends on the number of cavities and complexity shapes of mold. When the mold is prepared then the plastic melt is injected through an injection molding machine. For this process, a reciprocation screw injection molding machine is used, the granular material i.e the plastic resin is fed from the hopper of the machine and the further processing steps takes place inside the molding machine. These plastics are mainly created by melting pellets and cooling them i.e the final part can also be recycled. The mold used for thermoplastics is easily available. These thermoplastics products are used for consumer plastics because they don't have contact with high temperatures. The advantages of thermoplastic injection molding are good accuracy, better surface finish, good processing speed and the disadvantages are high cost and flaws may produced in the final product.

Injection Molding of thermosets: In the production of thermosets the cold material is injected into a hot mold and by curing process, the final product is produced.The equipment for injection molding of thermosets are in-line screw assemblies fitted to horizontal or vertical clamp machines. The equipment of thermoplastic can be converted into thermoset by changing the nozzle, screw and barrel. The equipment used for thermosets are similar to the equipment of thermoplastics but the difference is they reciprocate screw injection unit and the barrel length is short to avoid the premature curing and solidification of the polymer. These molds used for thermosets are rare. These products are cannot be recycled. These products are mainly used at high temperatures because these are having high temperature resistance. The advantages of this process are high strength products, good dimensional accuracy and better heat resistance products and the disadvantages are the molds are very rarely available.