Injection Molding

The injection molding process involves the use of a mold to produce parts by injecting melted material into it. This method can be used with various materials including glasses, elastomers, confections, and thermoplastics or thermosetting polymers. The material is heated, blended and then injected into the mold where it solidifies into the shape of the mold cavity. The mold is usually made of metal, such as steel or aluminum, and is crafted with precision to match the desired design of the part. Injection molding is commonly used for producing various parts, from tiny components to entire car body panels. In recent times, 3D printing technology using photopolymers has made it possible to create simple injection molds for low-temperature thermoplastics. The design of parts intended for injection molding must be carefully considered, taking into account factors such as the material used, desired shape, mold material, and molding machine properties to maximize the versatility of this method.

Multi-Shot Injection Molding

Multi-Shot Injection Molding is a method of creating multiple layers by consecutively injecting heated materials into a mold. The process involves inserting the materials in a specific sequence, which results in a layering effect between the materials and stronger inter-layer bonds compared to when the layers are applied to a cooled part, such as in over molding. This technique is often preferred when producing parts with varying mold geometries between different material layers.

Blow Molding

The process of blow molding involves creating hollow plastic parts by inflating a heated plastic tube to conform to a mold. The process starts with the raw material, in the form of pellets or granules, being melted and formed into a hollow tube, known as the parison. This parison is then clamped between two mold halves and inflated with pressurized air until it fills the mold and takes the desired shape, usually at pressures of 25 to 150 psi, lower than the pressure used in injection molding. Finally, the mold halves are opened and the finished part is removed. Blow molding is commonly used to create thin-walled, plastic, hollow parts such as bottles, containers, and storage tanks in a variety of shapes and sizes, from small items like water, soap, shampoo, and milk bottles, to larger items like plastic drums and tubs.

Compression Molding

Compression molding is a process of shaping preheated polymer by placing it into a heated mold cavity, which is then closed and compressed to ensure that the material touches all parts of the mold. This method is capable of producing parts with various lengths, thicknesses, and intricate designs, with a high level of strength. Thermoset composites are the most commonly used material in compression molding. This technique is favored by many industries due to its use of advanced composites, which are known to be stronger, stiffer, lighter, and more resistant to corrosion than metal parts. It is also easy to convert a metal part design into a compression molding design, and it allows for more complex geometries compared to typical laminated composites. In addition, compression molding offers longer fibers than plastic injection molding, resulting in stronger and stiffer materials. Hence, compression molding is considered as a balance between plastic injection molding and laminated compound fabrication, providing a cost-effective solution for manufacturers in many industries with its ability to create complex parts and reduce part cost and production time.

Rotational Molding

Rotational Molding, also known as RotoMolding, is a plastics molding technology which is ideal for making hollow articles. It is a casting technic but unlike most other plastics processes there is no pressure involved. Molds for the process are relatively inexpensive as they do not have to withstand pressure and therefore relatively short production runs can be made very economical-ly. RotoMolding is used to make a very diverse range of products. The process offers the product designer exceptional freedom as just about any shape can be produced. There is almost no limit to the size of moldings and there are literally thousands of applications. The concept of rotational molding is very simple. A plastic material, normally in powder form is placed into a hollow mold, usually made from cast aluminum or fabricated from sheet steel. The mold is closed and rotated slowly on two axis. The mold is then heated in an oven whilst rotating and the polymer gradually melts and ‘lays-up' on the inside of the mold. Once the polymer powder has fully melted the mold is moved to a cooling station and cooled usually with air and sometimes a fine mist of wa-ter. As the mold cools the part solidifies. When the material has finally cooled sufficiently to re-lease away from the mold surface the process is stopped and the product is taken out of the mold.

Vacuum Forming

Vacuum Forming is a simplified form of thermoforming where plastic material is molded into a desired shape by heating it, stretching it over a single-surface mold, and applying vacuum pressure to form the material against the mold. This process is used for creating permanent objects like road signs and protective covers. The mold used in this process usually has a minimum of 3° draft angle to make it easier to remove the formed plastic from the mold. Vacuum forming is capable of forming relatively deep parts if the plastic material is stretched before being brought into contact with the mold. Thermoplastics like high impact polystyrene are commonly used in vacuum forming because they are easy to mold, hygienic, and can maintain their shape even when exposed to warm water. Transparent materials like acrylic are also used in vacuum forming for applications in the aerospace industry. This process is often used in low-level technology classes as a simple way to mold.

Rubber Molding