Stitching in Metal
Page 51
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riNE of the most practicable methods of repairing small or large cracks, and even complete fractures. particularly in castings and forgings, has proved to be the process known as " Metalock," and its later developments, Metalace " and " M.asterlock."
It is only six years since the first repair by Metalock was carried out in Britain, which in this case was to one of the engine cylinders_of art oil tanker. The success of this and the speed with which it was effected -proved the efficacy of
the process, Year by year, Metalock (Britain), Ltd., Grand Buildings,
rafalgar Square, London, S.W..1, have developed until now they have 32 highly skilled operators based at strategic -points throughout the country. Much of the work is carried out on site, in other cases damaged parts are sent for treatment.
In the motor industry, permanent repairs are being made to such items as cylinder blocks, pistons, water pumps, machine; toOts and presses. One of the longest fractures , repaired was that in the cylinder. of a large oil engine,
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stitching" being required over a length of 32 in.. Despite this, the time taken was only ..three days:
The main requirement for a successful repair is a minimum thickness Of about 3,/16 in.„ of material in good condition. . The stitching is performed by cuttin2. slots
across the crack or fracture; this being 'done by drilling to a jig and linking the holes. Into each slot is driven, a key, which is locked solidly within the parent metal byfneumatic hammering. In a deep crack, several keys may be inserted. one at a time, their strength is known exactly, and that of the repair is governed by the number of keys employed and their sire, The Metalace process employs the keys in connection with studs, to seal completely cracks in cylinders, etc.. against leakage under pressure.
Where there is a break at a point of concentrated stress resulting from severe overloading, a Masterlock insert is prepared and secured in a suitably recessed part of the job by dowels cold-worked into matching half-holes belvveen the parent metal and the insert plate. In such a case the repaired part is much stronger than the original.
During a visit to the company's works in London. a representative of The Commercial Motor was much impressed by the rapidity of.the repairs, the quality of the workmanship and the many repeat orders received from satisfied clients.