23-09-2016, 10:29 AM
1455800362-InjectionMolding.pptx (Size: 1.12 MB / Downloads: 4)
Introduction
Injection Molding is a is a fast, high-volume closed mold process that generally involve forcing or injecting a fluid plastic material into a customized mold
The part and mold often can be designed so that no subsequent trimming or machining operation is required
There are 2 basic categories of plastic injection molding: thermoplastic and thermoset
Thermoplastic material is melted and forced through an orifice or “gate” into a relatively cool mold
Thermoset injection molding, a reacting material is forced into a generally warm mold
History
John and Isaiah Hyatt received a patent in 1872 for a plunger type injection molding machine for molding plasticized cellulose nitrate
In 1952 there was invention of reciprocating screw plasticizing unit by W.H. Willert
Conventional injection molding machines uses hydraulic setup.
Current trend is electric injection molding machines with advantage of greater precision and controllability
Key elements of the machine
Hopper: Stores the plastic material and dispenses as required
Clamping unit: Clamps the Mold, applies the required pressure
Control unit: Used to set the different process parameters like, temperature, cycle time, etc.
Mold: Customized unit to produce the required components
Plasticizing unit: Convert solid granules into liquid form and pushes into the mold
Hydraulic lines and motor: Used to push the material into the mold cavity