Gas assist injection molding is a subset of the plastic injection molding family. Gas assist, like structural foam molding, produces a lower-cost, lighter product than typical injection molding. Gas assist molding has become a key role in medical device manufacture because to its adaptability and cost advantages. Here are some things you should know about gas assist injection molding before deciding on a molding method for your project.
What exactly is gas assisted injection molding?
Gas help injection molding is a plastic injection molding technique that uses physical inert gas to fully pack out a product. After the injected resin, the gas is pumped into the mold, resulting in a hollow object that is light and affordable to produce. Nitrogen is the favored gas due to its availability and low cost. Gas assist molding is particularly beneficial in applications with thick geometries and intricate patterns. Internal gas assist injection molding and exterior gas assist injection molding are the two forms of gas assist injection molding.
- Internal gas assist
Internal gas assist introduces gas into the component shape, pushing the molten resin to expand outward and pack the mold. A hollow channel is left in the centre of the portion. Gas injection happens when the cavity is only partially filled with resin for particular sections. Following the addition of the gas, the remaining resin is injected. The gas aids the resin in filling the portion prior to packing it out. Internal gas assist molding is designed to produce lighter, hollow pieces with thick portions.
- External gas assist
When gas injection happens on one side of the part’s exterior, it is referred to as external gas assist. The high-pressure gas forces the uncured resin away from the tool, cramming it into the opposing side. Because the gas is in charge of packing the resin into the tool, the injection pressure may be reduced. Even gas distribution reduces component warping and internal stress, resulting in higher quality. External gas help makes it simple to pack out thick geometries that would otherwise have sink marks or warping from conventional molding.
Advantages of gas assisted injection molding
Several benefits exist between gas assist injection molding and standard plastic injection molding. Because the gas pressure pushes the plastic resin evenly across the mold cavities, it improves the appearance of molded items. It also speeds up the holding portion of the molding process, resulting in a shorter cycle time. Furthermore, the gas minimizes the amount of press tonnage necessary to fill up the item, lowering tooling and production costs. Gas assist enables engineers to make bigger, thicker, and more sophisticated moldable components that would not be achievable using standard processes. Due to their thick cylindrical designs, handles are some of the most typically manufactured gas assist parts, while others include doors, cabinets, and covers.
Gas assist injection molding design considerations
When developing gas assist molded components for manufacture, there are a few things to keep in mind. The part design must be modified to include controls for where, when, and how gas is introduced on the plastic surfaces. Gas zones and modified thicknesses are required in regions where gas is applied. Internal gas assist necessitates design changes such as overspills and gas pins. Overspill pins aid in the removal of excess resin, while gas pins serve as conduits for gas injection. To enter the gas at the precise timing and pressure during the molding process, specialized gas control equipment must be programmed. The operation of the gas pressing against the plastic causes a wavy unattractive marking on one side, which is a typical issue with external gas aid. Engineers should thus only utilize external gas help on items when the final assembly conceals the nonaesthetic side.
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