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7 KEEPING THEM RUNNING
Page 95
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will? Ron Cater /
Metal spraying has been used for many years to rebuild surfaces that are undersize through wear or through an error in machining. As many metals can be sprayed, a coating material that has special characteristics such as resistance to wear and/or corrosion can be chosen for reclaiming the part This means that a component which has been sprayed can give better service than the original. The porosity of a metalled coating, I am told, provides ideal oilretaining properties, particularly where high-temperature or heavyduty conditions make lubrication difficult.
Worn bearing diameters and flat surfaces can quickly be restored to standard dimensions at a fraction of the cost of a replacement part, and it seems that as very little heat is put into a component being metal-sprayed, aril as previous heat-treatment is not affected, there is no danger of distortion. Items such as armature shafts can be metal sprayed without removing the windings from the shaft, for instance.
A new process. known as the Type "N" Metallizing System. has been introduced by Metco. It has simplified both the metalspraying installation and the operation of the process. The new Type-"N" Gun is designed for use in a small maintenance department or any small engineering company where worn components are reclaimed. Even with frequent use, it becomes an attractive proposition. The low capital cost could well be recovered on the first job for which the process is used, Because the "N" Metallizing System is simple and fast, a component that has been accidentally machined undersize can be re-built and machined to correct dimensions while set-up. Similarly, inspection rejects can easily be fed back into a production line to be salvaged by metal spraying the mis-machined dimension. The normal method of applying a sprayed coating is by three simple operations—clean, metalspray, finish machine.
There are no troublesome dust or fumes with the -N" Metallizing System and the spray-gun is quiet in operation. Neither special exhaust systems nor separate location are necessary. Unlike other metal spraying processes, no compressed air is needed to operate the "N" gun: a cylinder of oxygen and one of acetylene is all that is required. Because most worn areas needing reclamation are diameters, the preparation, spraying and finish machining operations are often done on one setting in a lathe. Flat surfaces requiring metal spraying can be sprayed on a welding or similar bench. The simple operations are well within the capabilities of a lathe operator and are outlined in step-by-step illustrations supplied with the equipment.
The complete installation consists of a Type-"N" Metallizing Gun, a pair of hoses and oxyacetylene regulators. The total floor area required is room for a cylinder of oxygen, one of acetylene and space for the operator to stand.
Full details of the new process and equipment are available from METCO Ltd., Chobham, Woking. Surrey.