Gas injection moulding (GSI) technology is the process of injection of nitrogen gas under high pressure through the nozzle or mould wall into the molten polymer within the injection mould. This process cores out sections of the part, and leaves hollow areas.
GSI moulding is a relatively new process with good compatibility with the conventional injection moulding process. It is applied for the production of two main classes of components: thin, shell structures with hollow reinforcing ribs, such as TV cabinets; and fully 3-dimensional hollow objects, such as tubular components, handles etc.
Sri Dayaa Manufacturing Sdn Bhd’s auto gas assisted injection (AGSI) offers a lot of benefits to the manufacturing of polymer products, such as reduced moulded-in part stress, less warpage, reduced or no sink, and greater design freedom.
Advantages of Gas-Assist Injection Moulding
Why is the level of interest in gas-assist injection moulding so high? The primary reasons are that the “promised” advantages of this process are being delivered. Some of the potential benefits of gas-assist injection moulding are:
- Reduced moulded-in part stress
- Low shrinkage and warpage
- Reduced/eliminated sink
- Greater design freedom
- increased parts integration possibilities
- Improved surface appearance vs. foam (i.e., reduced/eliminated finishing)
- Hollow sections that provide easier part filling, longer material flow length, higher stiffness-to-weight ratio
- Reduced cycle time vs. solid sections
- Lower clamp tonnage requirements
- Lower injection pressures
- Reduced tooling costs as a result of replacing hot runner systems with gas channels
- More lightweight parts
Most thermoplastic materials are capable of being used in gas-assist injection moulding. Crystalline materials such as:
- polybutylene terephthalate (PBT)
This materials may have some advantage because they have a sharp melting point and are low in viscosity, allowing easy gas penetration. Material selection should be based on meeting application performance requirements such as stiffness, strength, performance at use temperature, and chemical resistance.
References : Hanser.de