Transfer moulding finish

Figure 10.12 Press-and-blow process (a) gob feeding, (b) parison pressing, (c) parison mould opening and plunger release, (d) transfer to finishing mould, (e) sagging, (f) blowing, (g) annealing and HEC.

Grade Selection Criteria Fire resistance. Process characteristics for injection moulding, extrusion, film production, transfer moulding, blow moulding and transfer moulding. Surface finish. Food contact approvals. 

In-mould labelling (IML) used for injection-moulded products and blow-moulded bottles is an alternative to self-adhesive or heat-transfer decoration, eliminating a finishing step. 

The described process is simple. The aim was to provide the first evidence for such a reactive surface modification injection moulding process. A transfer to a production system requires an optimisation of the modifier adding process. The principle of the surface modification injection moulding process can also be transferred to extrusion processes for the manufacture of semi-finished and profile products. 

In the blow and blow process the gob is dropped into an open blank or parison mould. The neck is formed by top blow and then the parison or blank is blown from the base (Figure 6.2). The blank shape supported by the transfer ring is then transferred to the finishing mould where it is blown into the final shape. This blow and blow process is the major process employed—usually with IS (i.e. independent or individual section) machinery Other machines include Roirant R7, S10 and Lynch 44. IS machines may have 4, 5, 6, 8, 10 or 12 stations. For small containers double, triple or quadruple gobbing may be employed. The last can give speeds of over 400 containers per minute. 

Alternatively a press and blow process may be used for wide-mouthed (and now certain narrow-necked) containers. The first stage is a gob feed into a mould which is followed by a plunger descending or ascending to form both the neck finish (at end) and the parison shape. As in the blow and blow process, the blank is then transferred to a finishing mould where it is blown into the final shape (Figure 6.3). 

The finished dry rubber and latex based rubber products can be vulcanized by several techniques depending on the type of rubber compound (dry rubber compound/latex compound), size of the finished product, and its shape and structure. Moulded rubber products are vulcanized by press curing using compression, transfer, or injection moulding presses. The vulcanization techniques other than moulding may be grouped into batch and continuous methods. The batch methods include the use of autoclaves, hot air/gas oven, and hot liquid/ water bath. Rubber products may be vulcanized at room temperature by cold curing either by immersion of rubber products in a carbon disulphide solution of sulphur chloride (SjCy, or by exposure to its vapour. 

The dimensional accuracy of investment casting will vary depending upon pattern contraction, mould expansion and contraction, and contraction of the cast metal. In general, a tolerance of 0.13 mm per 25 mm can be achieved on relatively small castings. A surface finish comparable with that of machining can be achieved by the transfer of the excellent finish of the pattern to the surface of the mould cavity by the investment technique. 

Mould release agents and processing additives are engineered to improve the production process and product quality. They facilitate optimum demoulding of the contents from the mould and the release agent should not transfer from the mould surface to the moulded part. Parts that are easily removed from the mould exhibit an attractive mirror-like finish and with less mould maintenance and wear, less cleaning of the part is required. 

Holding Ring. A bead (q.v.) in the finish of a glass bottle for use when the parison is transferred to the blow mould sometimes known as the back ring or TRANSFER RING. 

To maximise the mechanical properties of short fibre-reinforced thermoplastic composites, it is necessary to achieve effective stress transfer between fibre and polymer matrix and appropriate fibre alignment in the finished component relative to the direction of applied stress. The former requirement is governed primarily by the method of compounding, whilst fibre orientation is very dependent on moulding conditions [76]. 

Under this heading of manipulation is included any process whereby the solid plastics material, usually in powder or nib form, is converted to the finished end product. It embraces moulding by compression, transfer, injection or extrusion, blow moulding, rotational moulding, and any process whereby a layer of comminuted plastics material is heat-sintered into a finished unit. In all of them the product designer has to work very closely with the manufacturer not only of the plastics material, but also with the mould maker and to an ever-increasing extent with the maker of the moulding machine. 

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