Processing methods and molding processes of plastic molded parts
We realize with you custom injection molded parts made of plastic and complex plastic assemblies. Our experienced team will be happy to accompany you from the first design approaches and support you in the development of innovative products.
Our wide range of products includes a variety of plastic injection molded parts - from the smallest precision parts to functional housings and complex multi-component injection molded parts (2K / 3K processes, insert technology and outsert technology). Our goal is to meet the needs and requirements of our customers with our tailor-made solutions, even for small and medium-sized quantities at attractive conditions.
Information on various plastic processing methods
1. Archetype process
Thermoplastics and duroplastics are used in the primary molding process to produce plastic molded parts. The shapeless substances and granules or melts are processed into solid bodies.
Injection
Injection molding is an efficient and proven method of plastic production. Here, the plastic is injected under high pressure into the cavity of a mold, where it cools and hardens. The result is a high-precision molded part with a variety of material properties, such as flexibility, durability, and heat resistance. Injection molding also allows customization to specific design requirements such as color, texture and finish, creating unique and distinctive products.
As a discontinuous primary shaping process, injection molding offers numerous advantages over other manufacturing processes. It enables high production rates, consistent part dimensions and quality, and the manufacture of complex shapes with high precision. In addition, the process offers great flexibility in material selection to meet the needs of a variety of industries.
Although injection molding requires investment in equipment and tooling, the advantages of the process such as high production rates and consistent quality are cost effective for many industries. It is a tried and tested process that has been used in plastics manufacturing for decades and is essential for many applications.
plastic extrusion
The extrusion process is used in many industries to produce semi-finished products such as pipes, sheets, foils, profiles and textile fibers. It is a continuous process in which the raw materials are fed into a hopper in the form of powder or granules. They are then melted and compressed in the extruder barrel under high pressure and temperature. Using an auger, the liquid plastic is then continuously forced through a nozzle where it is formed into a durable semi-finished product. The process offers many advantages, including high production rates, consistent quality and high precision in the manufacture of semi-finished products. It is also possible to customize various material properties such as hardness, flexibility and color to meet the needs of the application.
Blow Molding / Extrusion Blow Molding
The preform is then transferred to the ready blow mold. The blow pin dips in there and the actual blow molding takes place by introducing compressed air through the blow pin. The preform is finally adapted to the inner contours of this mold by means of internal pressure. This process is called blow molding (forming). After the cooling time has elapsed, the tool opens and the finished article is demoulded. A typical identifying feature for extrusion blow molded plastic parts is a seam on the underside. The most commonly processed plastics for extrusion blow molding are the polyolefins polyethylene (PE) and polypropylene (PP).
Injection stretch blow molding of plastic
A special form of blow molding is what is known as injection stretch blow molding or stretch blow molding. PET bottles are created in such a process. The rather small PET blanks are first produced using the injection molding process and then expanded to their final volume by stretch blow molding. The PET preform is heated and mechanically stretched in the longitudinal direction by a ram, while circumferential stretching is carried out simultaneously with blast air at a pressure of up to 20 bar. Due to the low temperatures, high deformation forces are required. Hollow bodies that have been produced using the injection stretching process have a significantly higher strength and are suitable, among other things, for carbonated drinks. However, such moldings are limited in terms of shape
2. Multi-component injection molding / multi-component injection molding
With multi-component injection molding, multi-colored molded parts can be realized or molded parts can be combined with hard-soft combinations. Both two-component molded parts and three-component molded parts can be created with just one tool. The most common manufacturing processes for combining two melts are the overmolding process and the sandwich molding process.
Multi-component injection molding using the overmolding process
In the overmolding process, a previously manufactured injection molded part is sprayed over with a second melt in a subsequent process step. The selected thermoplastics are injected against or on top of each other. In this case, for molded parts in which a firm connection of the components is desired, they should have adhesion to one another. (e.g. PP/PE or PC/ABS). However, there are also multi-component molded parts in which the individual parts should remain movable with one another, eg toys and joints.
Multi-component injection molding using the sandwich molding process
The sandwich molding process (also known as co-injection process) usually produces parts in which the internal component is not visible because it is completely encased by the outer material. Reasons for using sandwich molding processes are, on the one hand, the reduction of costs by using a cheaper filling material or recycled material as the invisible core of a product, and, on the other hand, higher mechanical strength combined with high surface quality.
In this process, the individual components are injected directly one after the other into the injection mold (the cavity). The melt that flows in first lies continuously against the wall of the mold, where it is pushed by the second melt. The second injected melt forms the core or the interior of the finished injection molded part. The reason for this is the so-called swelling flow phenomenon, which ensures that the components completely envelop each other perfectly, as well as the laminar flow of the melts.
