Running-in the New Mould
The very important factor of mould operation and maintenance which is of a wide general nature deserving the closest attention, relates to the running-in of the new mould after it has undergone, successfully, initial tests and before it may safely be brought up to the maximum production speed
Very often and in most China plastic injection molding companies, if the sample mouldings taken from a new tool during its test period are found to be satisfactory by the client, and sanction to proceed with bulk production has been given, the mould is then removed from the machine and completely stripped for final examination and the performance of other finishing-off operations.
Thus the main blocks containing the matrices as well as other essential components will be hardened and finally polished up. The ejector gear may be fitted in full or final adjustments made in the disposition of the ejector rods. Numerous adjustments will also be carried out as revealed to ensure smoother working of the tool. All this accomplished, the mould will then be finally assembled together completely for a further test. Should it pass this second final test satisfactorily it will be retained in production.
But it is sound practice to take special precautions at this stage to prevent the mould from being worked at its maximum speed right away, the much preferred practice having been found to start at a slow rate of production for a short time and then very gradually to increase it until the highest rate of output is attained. This usually occupies a considerable time and in the case of a compression mould should extend over the moulding of the first 500 articles, or sets of articles in the case of a multiple impression tool- With an injection type mould it might be necessary to retard full-scale production until anything up to 5000 shots have been taken，dependent upon the complexity of the mould, of course.
Now the point to be noted in this connection of mould running-in periods，is that should there be great pressure of work on the China plastic moulding shop, or if the client is clamouring for overdue deliveries of the parts, to mention two only of the numerous reasons which may operate, this running-in process is sometimes drastically telescoped, and even omitted altogether.
Sometimes such a step is taken for no other reason than the undoubtedly natural desire of those concerned most intimately in the manufacture of the new mould to ascertain exactly what it is capable of in the way of speedy operation. Whilst such pride in workmanship and the product is perhaps understandable，it is nevertheless a very risky practice and one which at all times should be discouraged.
It is an action which has been found repeatedly to be the precursor of serious troubles, such as seizure of sliding or rotating cores，ejector rods, scoring of mould cavities, sticking cores, warping in the mould blocks, undue stiffness in working the mould, and consequent additional stress on some vital part, with its eventual failure. These of course arc but a few of the troubles likely to arise.
As is well known，a completely new mould will normally run much hotter and stiffer in its operation than one which has been in use for some time, and thereby has become run-in to a smooth condition of working. Every component is new, with fits between the various parts good, and the degree of such fit requires a minute amount of casement which can best be secured by steady, careful operation of the tool itself.
Hence if subsequent operating snags and mould troubles are to be avoided a little patience and caution in the handling and application of a brand new mould to its productive work will be found to afford ample recompense in the shape of longer runs, absence of the many little hold-ups and minor variations on troubles, and all-round reduced need for expert maintenance supervision.