Mould Carrying system

Cannon provides different mould-carrying systems, each customised to meet the customer s needs. The most common solutions are conveyors and turning tables. In the last part of this section some innovative concepts, which provide a more compact layout, a minimised investment requirement and a maximum degree of flexibility in a changing manufacturing scenario, are presented. 

Developed in the early 1980s as a revolutionary tool for the production of foamed refrigerator doors, the well-known concept of the rotary polymerisation system is now being proposed as a compact and simple mould-carrying system for the production of automotive seats (see Figure 3.12). 

The anionic polymerization of caprolactam (CL) is a fairly old polymerization technique by which molten caprolactam is polymerized in a mould by means of an accelerator and a basic catalyst at a temperature lower than the melting point of the polymer to be formed. With a correct choice of polymerization system and by optimization of the polymerization conditions the polymerization can be completed in about 3 minutes so that the reaction can be carried out in a specially adapted RIM machine. 

The system is composed of two shuttle-bed clamps served by one metering unit, which dispenses the pre-heated heavy layer in the mould. Pre-heating is carried out using a special infra-red heater, which incorporates easily adjustable, special low thermal-inertia resistances. When a vacuum is applied to the mould, the material adheres to the lower mould half, taking on its shape and embossed design. 

The most numerous researches have been carried out upon water-membrane systems, for which a summarising paper by Carson (1) has outlined the main methods of measurement. To prevent lateral diffusion of water through the edges of the specimen, or between it and its supports, various devices have been adopted. The edges have been moulded in wax, or compressed with a mixture of beeswax and resin. Shellac, petrolatum, and rubber have been used for the same purpose or the cell may be mercury sealed. Films of lacquers and paints may be made by painting the lacquer on suitable surfaces, such as amalgamated tin-plate (2), and then peeling off the dried membrane. 

If this is the case, it would be necessary to remove all the water present in order to force the equilibrium completely toward diimine formation and the establishment of permanent cross-links. Experimental evidence for this proposition is that a full state of cure is not attained if the long heating process is carried out in the mould, i.e., in a virtually closed system. Hydrolysis is also demonstrated by the fact that much of the diamine present in a vulcanizate can be extracted by treatment with water. 

For many years the Society of the Plastics Industry, Inc. (SPI) in the United States has romoted a voluntary coding system for the identification of the resins used in rigid plastic containers. The system comprising a number 1 to 7 and several letters is generally moulded into the bottom of a container. For example, the number 1 and the letters PETE indicates that the container is made of polyethylene terephthalate while the number 2 and the letters HDPE signify that the container is comprised of high density polyethylene. Thirty-nine U.S. states have mandated that plastic bottles 16 ounces or more and other rigid plastic containers of 8 ounces or more must carry the SPI resin code. 

The whole HR system is divided into temperature control zones temperature measurement and control are carried out with the aid of automatic regulators separated from the mould. 

Mould operations may run into problems if trained staff are not available. Start-up of the HR system, change of plastic, stopping and, if necessary, cleaning of hot runners cannot be done without some knowledge and observance of certain principles. For the same reason, repairs and maintenance should be carried out by trained staff only. Damage to moulds caused by unskilled servicing generally leads to serious financial losses. 

---