 Basic concept diagram of gas-assisted injection molding | |
| Process type | Injection molding process |
|---|---|
Gas-assisted injection molding is a molding process where an inert gas is injected into the melted plastic pushing it further into the mold and resulting in hollow parts. [1]
The basic concept of the gas-assisted molding process is quite similar to the regular injection molding process. In gas-assisted molding, the plastic material is injected into the mold cavities like the regular injection molding process but only up to 70%~80% of the mold volume. The melted plastic in contact with the mold walls begins to solidify, then nitrogen gas is injected into the mold through strategically designed and placed gas inlets, providing pressure that pushes the plastic into the mold extremities. The path of the bubble is controlled by taking the path of least resistance through the hottest, least viscous plastic, which keeps it centered from the colder walls of the mold. Finally the molded part is ejected like the regular injection molding process. [2]
This process forms hollow parts that are cheaper than traditionally injection molded equivalents. Molded parts also cool faster in this process. There is also usually less shrinkage as the thicker wall sections are hollow. [3]
Some of the benefits of this process are: [4]
This molding technique is very difficult to apply to multi-cavity molds, especially if the cavity sizes are dissimilar. Clear or transparent plastic materials are an inappropriate option for this technique as the cosmetic-appearance can deteriorate. [5]
Injection molding is a manufacturing process for producing parts by injecting molten material into a mould, or mold. Injection moulding can be performed with a host of materials mainly including metals, glasses, elastomers, confections, and most commonly thermoplastic and thermosetting polymers. Material for the part is fed into a heated barrel, mixed, and injected into a mould cavity, where it cools and hardens to the configuration of the cavity. After a product is designed, usually by an industrial designer or an engineer, moulds are made by a mould-maker from metal, usually either steel or aluminium, and precision-machined to form the features of the desired part. Injection moulding is widely used for manufacturing a variety of parts, from the smallest components to entire body panels of cars. Advances in 3D printing technology, using photopolymers that do not melt during the injection moulding of some lower-temperature thermoplastics, can be used for some simple injection moulds.
Blow molding is a manufacturing process for forming hollow plastic parts. It is also used for forming glass bottles or other hollow shapes.
Rotational molding involves a heated mold which is filled with a charge or shot weight of the material. It is then slowly rotated, causing the softened material to disperse and stick to the walls of the mold forming a hollow part. In order to form an even thickness throughout the part, the mold rotates at all times during the heating phase, and then continues to rotate during the cooling phase to avoid sagging or deformation. The process was applied to plastics in the 1950s but in the early years was little used because it was a slow process restricted to a small number of plastics. Over time, improvements in process control and developments with plastic powders have resulted in increased use.
A hot runner system is an assembly of heated components used in plastic injection molds that inject molten plastic into the cavities of the mold.
The heat deflection temperature or heat distortion temperature(HDT, HDTUL, or DTUL) is the temperature at which a polymer or plastic sample deforms under a specified load. This property of a given plastic material is applied in many aspects of product design, engineering and manufacture of products using thermoplastic components.
In-mould labelling is the use of paper or plastic labels during the manufacturing of containers by blow molding, injection molding, or thermoforming processes. The label serves as the integral part of the final product, which is then delivered as pre-decorated item. Combining the decoration process with the moulding process cuts the total cost, but can increase the manufacturing time. The technology was first developed by Owens-Illinois in cooperation with Procter & Gamble to supply pre-labelled bottles that could be filled on the product filling line. This was first applied to Head & Shoulders shampoo bottles.
Plastics extrusion is a high-volume manufacturing process in which raw plastic is melted and formed into a continuous profile. Extrusion produces items such as pipe/tubing, weatherstripping, fencing, deck railings, window frames, plastic films and sheeting, thermoplastic coatings, and wire insulation.
Fusible core injection molding, also known as lost core injection molding, is a specialized plastic injection molding process used to mold internal cavities or undercuts that are not possible to mold with demoldable cores. Strictly speaking the term "fusible core injection molding" refers to the use of a fusible alloy as the core material; when the core material is made from a soluble plastic the process is known as soluble core injection molding. This process is often used for automotive parts, such as intake manifolds and brake housings, however it is also used for aerospace parts, plumbing parts, bicycle wheels, and footwear.
Injection molding of liquid silicone rubber (LSR) is a process to produce pliable, durable parts in high volume.
An injection molding machine, also known as an injection press, is a machine for manufacturing plastic products by the injection molding process. It consists of two main parts, an injection unit and a clamping unit.
Low pressure molding (LPM) with polyamide and polyolefin (hot-melt) materials is a process typically used to encapsulate and environmentally protect electronic components. The purpose is to protect electronics against moisture, dust dirt and vibration. Low pressure molding is also used for sealing connectors and molding grommets and strain reliefs.
Plastic forming machines, or plastic molding machines, were developed on the basis of rubber machinery and metal die-casting machines. After the inception of the polymer injection molding process in the 1870s, plastic-forming machines were rapidly developed up until the 1930s. With the gradual commercialization of plastic molding equipment, injection molding and extrusion molding became the most common industrialized processes. Blow molding is the third-largest plastic molding method after the injection molding and extrusion blow molding methods.
Thin wall injection molding is a specialized form of conventional injection molding that focuses on mass-producing plastic parts that are thin and light so that material cost savings can be made and cycle times can be as short as possible. Shorter cycle times means higher productivity and lower costs per part.
Conformal cooling channel is a cooling passageway which follows the shape or profile of the mould core or cavity to perform rapid uniform cooling process for injection moulding or blow moulding processes.
Injection mold construction is the process of creating molds that are used to perform injection molding operations using an injection molding machine. These are generally used to produce plastic parts using a core and a cavity.
Injection molding has been one of the most popular ways for fabricating plastic parts for a very long time. They are used in automotive interior parts, electronic housings, housewares, medical equipment, compact discs, and even doghouses. Below are certain rule based standard guidelines which can be referred to while designing parts for injection molding considering manufacturability in mind.
Multi-material injection molding (MMM) is the process of molding two or more different materials into one plastic part at one time. As is the case in traditional injection molding, multi material injection molding uses materials that are at or near their melting point so that the semi-liquidous (viscous) material can fill voids and cavities within a pre-machined mold, thus taking on the desired shape of designed tooling. In general, advantages of MMM over other production techniques include, but are not limited to, creating parts that have an elastic modulus that varies with location on the part, creating a single-structure part with different regional materials, and also creating a single part with multiple independent polymer colors. Applications range from simple household items like a toothbrush to more heavy duty construction of items like power tools.
Transfer molding is a manufacturing process in which casting material is forced into a mold. Transfer molding is different from compression molding in that the mold is enclosed rather than open to the fill plunger resulting in higher dimensional tolerances and less environmental impact. Compared to injection molding, transfer molding uses higher pressures to uniformly fill the mold cavity. This allows thicker reinforcing fiber matrices to be more completely saturated by resin. Furthermore, unlike injection molding the transfer mold casting material may start the process as a solid. This can reduce equipment costs and time dependency. The transfer process may have a slower fill rate than an equivalent injection molding process.
Micro injection molding is a molding process for the manufacture of plastics components for shot weights of 1 to 0.1 grams with tolerances in the range of 10 to 100 microns. This molding process permits the manufacture of complicated small geometries with maximum possible accuracy and precision.
Cube mold technology is a molding process for the manufacture of plastics components. This molding process allows to manufacture circular parts. This technology was introduced by Foboha and Arburg.
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