The first, hard material comes into the mould from the right. At the same time, the  soft material is injected in the middle of the mould. The mould opens and the finished part is ejected on the left. The semi-finished part on the right is transported  to the left cavity by the handling system. In Figure 2.29 the top view of the moving half is presented. For this type of mould  the shifting takes place in the moving half.

In Figure 2.30 the whole mould—moving half and fixed half—is presented.

2.2 Rotary Table Technology 

A common technology for multi-component injection moulds is the mould with  rotary table. With this technique the semi-finished part is not shifted but stays  in the mould.

 In contrast, one half, in our example the moving half, rotates by 90°  on the injection moulding machine between the first and the second injection  processes. Depending on the size, complexity, and shape of the plastic part, the rotation can be big or small. For a large 2-C part the moving half rotates by  180°. The injection mould then has two cavities, one for the soft and one  for the hard material. For smaller 2-C parts there can be for example eight cavities in an injection  mould, four soft and four hard. The moving half rotates by only 45° between  the injection of the hard and soft material. 

Our example is a cover from a hard inner material with a circumferential seal from  a soft material on the outside. The tool is a 4-component injection mould with two  cavities each. In Figure 2.31 the front and back sides of the cover are displayed. Both materials  are injected via a hot runner with needle valve. This technology is described in  detail in Section 3.9.11.

In the moving half four identical cavities are incorporated in the four inserts. Two  different inserts are installed in the fixed half. The first two inserts have the  contour for semi-finished parts. The insert is formed so it covers the area where  the sealing is injected in the second step of the process. In both other inserts on  the fixed half the area of the sealing remains uncovered. In turn, the edges of the  semi-finished part are sealed with the insert. Thus, the soft material only comes in  contact with the semi-finished part where it is desired. In Figure 2.32 the differences between the two fixed halves are shown. For this  mould the materials are defined through different fixed halves. They have the sealing for both the semi-finished part and between the semi-finished part and the  seal.

Our injection mould example has an integrated rotary plate in the moving half. The  clamping plate remains screwed tight to the machine and the cavity plate is rotated  90° upwards and back via a small gear. Both mould halves must fit together exactly in both positions, 0° and 90°. The flat guiding units, which are mounted on  the side of the mould, assume this task. On the moving half there are eight fixtures  (four for every position) and four guiding rails are attached to the fixed half. In Figure 2.33 the entire moving half of our example injection mould is shown. It is  evident that all four cavities are the same.