Effects and Influence of Mould Design upon Maintenance
It is an unquestioned truism that mould maintenance, in reality, originates in the design department when the core features of the mould mechanism are worked out.Moreover, they, in turn, are reflected in the manner of operation, disposition of wearing and bearing pressures, and the complete ability of the tool to withstand the duties laid upon it.
A mould designer can devote some consideration and also apply a little foresight to the probable working conditions to which a particular projected design will eventually be subjected.Many minor snags of both construction and operation may be foreseen and forestalled by the provision of simple modifications which will be comparatively easy to inaugurate at first stage.
The mould designer possessing wide and up-to-date workshop experience will have the ability to visualize the entire construction method of manufacture and functioning even before transmitting any of its design details to paper. He will build up a purely mental provisional design outline, picturing all the various parts, with their respective functions, movements in relation to each other, and broadly in what manner each will be constructed and produced.
If the designer is the possessor of useful machining knowledge as applied in plastic mould manufacture, he will be far better equipped to assess the extent and effects of stresses，wear, and pressures likely to be imposed on every component part of the mould when in service, and what is sometimes equally important, during the various processes of its manufacture.
It often happens that some delicate mould component is unduly strained or weakened by machining operations performed on it before ever it has been assembled into place and exposed to working conditions.
Thus among other important things, he will gain a good idea of the power which will be required for the withdrawal of sliding cores, or that needed to operate ejector mechanisms, the effects of pressure, heat, or moisture upon the various metals used in the mould，which are difficult to calculate theoretically.
With such knowledge available at the initial stages of the mould design, the designer will be in a much better position to foresee the numerous operating difficulties likely to arise later，and accordingly be enabled so to adapt any design project as to ensure maximum life and efficiency.
Much has been written previously on the subject of satisfactorily relating the features of a mould design to preferred moulding and operating requirements entailed in the various moulding processes. Numerous illustrations were presented demonstrating selected mould constructions，and the reasons underlying their selection in preference to other types, giving at the same time the practical advantages accruing from their application.
From these illustrations, it will have been appreciated how important a part may be played by the designer in creating those mould constructions which best ensure the minimum amount of maintenance attention as well as the maximum suitability in respect of the finished articles desired.
Certain well-defined methods of construction will be noted, these having been proved over and over again in actual working practice to give most satisfactory operation and product.
These examples of designs and methods will in each ease be confined to some special unit or function of a plastic mould, such as cores, cjectors，sprues, dowels and so on throughout the whole range of conventional mould components.