Press-moulded compounds

Distitron 330/25 An unaccelerated, orthophthalic resin offering good wettability, suitable for RTM manufacture. Also has application in cold-press moulding and in the manufacture of hot-press moulding compounds. ... 

An unaccelerated, high reactive, chemical resistant, isophthalic resin suitable for the manufacture of pultruded profiles exhibiting good mechanical properties. Can also be employed for the manufacture of hot-press moulding compounds and centrifugal casting. 

An unaccelerated, high reactive, orthophthalic resin for the manufacture of hot-press moulding compounds. 

Compression moulding (hot press moulding) Moulding compounds (often complex mixtures, e.g. dough or bulk moulding compounds) prepared in Z-blade mixer and heated under pressure in closed mould Small to medium articles, especially electrical mouldings large capital outlay... 

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

Hot Press Moulding—Heated matched dies are loaded with thermosetting compound and pressed together until cured. 

Hot press moulding can be carried out either using dry reinforcement to which a resin mix is added when in the tool or by the use of a previously produced compound of resin... 

ERF Ltd of Sandbach, Cheshire produce lorry cabs clad with glass-reinforced plastics (GRP) panels. The panels are hot-press moulded from sheet moulding compound, (SMC) then fitted to the steel frame of the cab (the safety cage) using an ERF patented assembly technique. 

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. 

A third form of both thermoplastics and thermosetting compounds takes the form of a sheet material that is press-moulded or stamped. It comprises a mat of reinforcement (which can include non-woven or woven structures, with chopped or continuous filament reinforcement) impregnated with the thermoplastic or thermosetting resin. 

Cure promoters include metal compounds, for optimal cure hot press moulding acetylacetone, with ketone peroxides and cobalt accelerator for a short geltime, giving a fast cure at room temperature and at elevated temperature and tertiary dodecyl mercaptane, for a gradual cure and moderate peak exotherm, in filament winding. 

Compression moulding is carried out on moulding powders or sheet moulding compounds (SMC). The presses are vertical, with the hydraulic cylinder above or below the horizontal platens. The mould is heated to between 160 to 200 C, being thermally insulated from the platens (Figure 1.9). The required amount of prepolymer (mixed with catalyst or curing agent) is placed into the open mould it is then closed and pressure is applied to cause the material to flow around the cavity. The mould remains closed until the... 

The method of manufacture of solid rubber products by simultaneous shaping and vulcanising. An uncured blank of rubber compound is placed in the bottom half of a mould, the top half of the mould placed in position and the mould placed in a heated hydraulic press. The press performs the dual function of both closing and heating the mould. See Transfer Moulding and Injection Moulding. 

The essence of the early 1960s process was that one injection unit fed 4, 6, 8, 10 or 12 vertical presses on a rotating mould carrier. Sometimes two injection units were used at different mould stations, one injecting a soft upper compound for a bootee and the other a harder sole compound. Sometimes two different coloured compounds were used. 

For applications requiring two different compounds, such as a double hardness sealing ring or a two colour rubber shoe sole, some machines have two injection units. One injects into the bottom/centre mould plate and the other into the parting line. Two injection units on a singlestation vertical press are used in combination with twin rotating cavity plates. 

In commercial use are a wide variety of machines which transfer fixed volumes of compound to clamped moulds, by the operation of a ram in a cylinder fed with pre-heated slugs. These machines are capable of high speed semi-automatic cycling and are a great advance over the use of loose transfer moulds in conventional presses. The components which are produced are to a large degree flash-free, it only being necessary, in the majority of cases, to remove the injection feed and runner system. 

Briefly, a measured amount of the thermosetting compound is placed in the cavity of a heated mould which is attached to the platens of an hydraulic press. The temperature of the mould may be (as an instance) 150°C. When the press is closed and heat and pressure applied the material flows and fills the cavity excess (known as flash ) escapes from the mould. Heat applied causes cross-linking and hardening of the material the moulding sets in the shape of the cavity and after a pre-determined time (perhaps three minutes) can be removed. Pre-heating the material (to, say, 70°C) can be employed as a method of shortening cycle times. 

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