The mark 9 clip

The Mark 9 clip is a new design. It weighs 4 g compared with 6 g for the Mark 8, and the design allows better alignment of stress. Thus the Mark 9 makes better use of material. 

This redesign of the clip to give the Mark 9 version is a good example of the modification of a basic design to take account of the processing and behaviour in service of the selected plastics material. 

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The Mark 9 clip has a centrally positioned stiffening rib, which aligns the stress correctly in service, and, in production, provides a good flow channel for the molten polymer during injection moulding. The stress now develops principally in the web section (B in Figure 5.2), and this can be calculated for various service conditions. 

Figure 5.2 shows the general outline and principal dimensions of the Mark 9 clip. 

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