DOUGH MOULDING

To obtain a strong busbar mounting system, suitable to withstand the electrodynamic forces arising out of a system fault, modern practice is to make use of thermosetting plastics, such as DMC (Dough Moulding Compounds)... 

The dough moulding compounds were originally developed in an attempt to combine the mechanical properties of polyester-glass laminates with the speed of cure of conventional moulding powder. In spite of their somewhat high cost they have now established themselves in a number of applications where a mechanieally strong electrical insulant is required. 

An imprecise term used sometimes in the sense of masterbatch, sometimes with the meaning of a blend of compounding ingredients for subsequent addition to the elastomer on a mill or in an internal mixer. Premix moulding is the same as dough moulding. 

Dough Moulding Compound Dynamic Mechanical Thermal Analysis Direct Resin Injection and Venting Differential Scanning Calorimeter Differential Thermal Analysis Elongation at Break... 

Acrylonitrile-butadiene-styrene (ABS) Dough moulding compound Polyamide (PA)... 

The fabrication techniques for thermosetting resins are complicated because they are normally used with fabric reinforcement, but some filled epoxies containing molybdenum disulphide are available as two-component systems for casting or as solid bar for machining. Dough moulding compounds are used for rapid production of components. 

Transfer molding is used for the manufacture of small components and is particularly useful with multi-cavity tools and where small inserts are to be moulded in. Materials used are polyester and epoxide dough moulding compounds, although a new liquid resin injection technique is reported. 

Dough Moulding Compound (DMC)—A mixture of chopped fibres, fillers and thermosetting resin, used in hot press moulding and injection moulding. 

As indicated earlier, the materials may be either in the form of compounds or resins and fibres separately. Sheet moulding compound (SMC), dough moulding compound (DMC) and bulk moulding compound (BMC) use polyester resin plus filler, catalyst, pigment, low profile additive, etc. 

Two cab parts are moulded in dough moulding compound (DMC) - the fascia glove compartment lid and door handles. The roof and extension panels were cold-press moulded. Thus, three distinct GRP processes are used in the construction of the cab SMC, DMC, and CPM, but predominantly the former. 

The dough moulding compound consists of an unsaturated polyester resin system mixed with Norwegian talc (Dolomite) and glass fibre of short staple-length (3-12 mm). The resin system has been specially developed for this purpose, as already mentioned. The mixing process itself is in two stages. 

The following account of how the newly developed headlamps were evaluated is taken from The development of a dough moulding compound for headlamp reflectors , in the Lucas publication Plastics Headlamps . 

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