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Term Definition
Electric moulding machines

Moulding machines in the past were primarily hydraulic based. This means that one or two big electric motors are continuously turning hydraulic pumps which produce hydraulic pressure. This pressure is then directed to the region of the machine that requires it. So during the mould closing phase for example, the oil is pushed into the rear of the mould closing cylinder. During injection, the oil is pushed into the rear of the screw piston. However, there are disadvantages with this

•   There is a large wastage in energy as the electric motors are continuously running, even if the energy is required or not.
•   There is a time delay as the oil is directed through the various valves to the right place in the right proportion.
•   There is an inbuilt inconsistency as the hydraulic oil will perform differently when it is cold compared to when it is hot.
•   There is a lag in performance of hydraulic fluids that means accuracy to within 0.01 mm is practically impossible to achieve.
•   Usually the machine can only perform one function at a time
•   The hydraulic oil requires a constant supply of cooling water.

With All Electric machines, the one large or two large motors that power the hydraulic pumps are replaced by a series of electric motors that power each individual machine operation. This means the following • When no part of the machine is actually moving, i.e. during the cooling phase, no energy is being used. • Reaction time on electric motors is much faster • Good quality servo motors will have superb repeatability regardless of running time or climatic conditions. • They will be accurate to within 0.01mm. • Multiple functions can happen at one time, resulting in faster cycle times. • The only external cooling required is for the hopper throat.

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