Gas Assist Injection Molding is a type of injection molding that uses both plastic and gas to fill an injection mold. The main benefit of this manufacturing process is its ability to form hollow parts quickly. It is advantageous for different applications due to a variety of reasons. These include but are not limited to producing parts that are smooth and extremely cleanable while offering increased strength and rigidity, weight reduction, design flexibility, and improved surface finish.
Additionally, gas assist molding usually has a shorter cycle time than solid molding, which can lower production costs. In order to take advantage of the benefits that come with this process, it is important to be mindful of gas entry and exit locations, select the geometries that will work optimally with the design, and avoid sharp corners that could result in weak spots.
Keep in mind that gas assists injection molding and blow molding techniques are different from each other. Gas assist molded parts to have thicker walls and smaller hollow cores. This design reduces the weight of the part by around 10%.
Blow molded parts have thinner walls and larger hollow cores. This design can reduce the weight of the part by up to 80%. In general, gas assist molded parts are sturdier than blow-molded parts, but not as sturdy as traditional injection molded parts. Seeking help from a gas assist injection molding specialist is the best way to ensure that your tubular structure designs are manufacturable and sturdy.
Types of Parts
Gas assist injection molding can be used to produce two types of parts: contained-channel parts and open-channel parts. Contained-channel parts include tubes, armrests, handles, and frames. Some parts are a mixture of these two types.
Tubes, armrests, handles, and frames are all examples of contained-channel components. These items are made out of a thicker section or channel that the gas must pass through. The components are often easier to process because the gas has a well-defined path through which it can travel and there are no thin-walled sections that need to be kept gas-free.
Open-channel items, such as access covers, panels, shelves, and chassis, have a few defining characteristics. Most notably, the components have very thin walls with gas channels running through them. This makes the production of these parts more difficult, as the gas can seep into the thinner portions of the component (a process known as fingering).
What Makes it Different?
Gas assist injection molding is a technology that allows for various parts with complex designs and differing wall thicknesses to be easily molded as a single part. With traditional injection molding, packing pressure is applied by forcing more molten plastic through the feed gates of the material.
Internal pressure significantly increases when gate freeze-off occurs during the injection molding process. Gate freeze-off happens when the gate cools and prevents molten plastic from flowing into the mold cavity. The time it takes to reach this stage is known as ‘freeze time.
As pressure is applied, the component will begin to cool down. The areas of the component farthest from the gates will freeze first, and pressure will no longer be able to be applied to them. However, as packing pressure is applied, more resin is driven into the region closest to the gates.
The pressure difference between the resin densities in the portion can create tension and warping as the part cools and shrinks at varying speeds. Gas assist injection molding can be introduced to solve this main problem of traditional injection molding by reducing the internal cavity pressure.
The gas assists injection molding technique helps to reduce common traditional injection molding defects such as flow lines, discoloration, distortion, and warping. This results in better dimensional control and improved quality of the produced part.
Additionally, gas assist injection molding is cost-effective. Thicker components can save up to 30% on material utilization by not needing to pack the material which results in a hollow core. This reduction in production costs can be directly translated to cost savings.
The components produced with gas assist injection molding are lighter in weight than those made with conventional injection molding. The primary reason for this is that the procedure uses less space and material, resulting in a stronger product that isn’t too heavy. However, parts can still have thick walls for increased strength.
This molding technique has also a faster cycle time since there is no molten core, the material in the mold cavity hardens faster and the component may be ejected sooner.
Gas assist injection molding is a manufacturing process that creates smooth surfaces on plastic products. This makes it easier to obtain the required design with very few alterations or subsequent operations. As a result, the plastic product can be ready for market distribution as soon as it has been ejected from the machine.
One of the most interesting developments in the injection molding industry in recent years is the possibility of using gas assist injection molding. It is a new way to manufacture plastic parts that changed the game for many industries. Gas assist injection molding has been chosen by companies to manufacture plastic parts because of the benefits it has over other traditional injection molding processes.