Engine Line Boring

Large generating sets, marine diesel engines and compressor main bearing bores often experience damage during the failure of a Crankshaft leading to requirement for repair or the more costly and time consuming process of replacement. In-Situ Machining (UK) Ltd are leaders in the field of Engine line boring and have successfully supported our clients over years to help alleviate the cost and timeframe associated with replacing components after failure. The company has a vast range of in-line boring machines and associated laser and optical alignment tooling and accessories to cover most engine types requiring engine bedplate rejuvenation, whether they be the conventional bedplate layout or an under-slung configuration. Repairs carried out by our experienced Engineers can take the form of repairing individual main bearing pocket bores or machining the complete line of bores as necessary. Working closely with the engine manufacturers, owners or both, a defined work scope is formulated and the work administered in accordance with OEM design standards.
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There are various ways in which to repair these bores and it very much depends on the maker’s preferences. Often bores are machined oversize, thermal sprayed and finally bored to standard size. Though rarely used selective plating in another means of repair, again bores are machining oversize, electro-plated before machining to standard sizes. Sleeving of main bearing bores is another common method often adopted to repair damaged bores, this procedure requires the bores to be machined to allow the fitting of a make-up sleeve and secured with a series of radially fitted screws prior to machining to design size. An allowance is left in the sleeve for final machining to standard size.
In each of the above repair methods it is only the lower half bearing bore that requires attention in the case of a conventional bedplate and the upper half bore of the under-slung engine type. The mating bearing caps can be reused, but more often than not, new bearing caps are advised and provided by the manufacture with the half bore having an allowance left on the diameter for final machining on assembly. Associated repairs and procedures allied to bedplate main bearing bore work would take the form of advanced metal stitching of heat induced cracking, milling of bearing cap fit location and possible make-up plating to remove fretting and wear.

Engine Line Boring

Thermal Spraying

Thermal spraying is an option for repair of damaged and worn bearing pockets. The bores are machined out to remove all damage and then sprayed to re-build the removed material. Thermal spraying is a process in which material in the form of wire or powder is heated until it reaches a molten state. It is then projected via means of air or gas to deposit a layer on the receiving component. This process can be repeated multiple times to allow material build up to the desired specification.

Laser & Optical Alignment

There are various ways in which to repair these bores and it very much depends on the maker’s preferences. Often bores are machined oversize, thermal sprayed and finally bored to standard size. Though rarely used selective plating in another means of repair, again bores are machining oversize, electro-plated before machining to standard sizes.
Sleeving of main bearing bores is another common method often adopted to repair damaged bores, this procedure requires the bores to be machined to allow the fitting of a make-up sleeve and secured with a series of radially fitted screws prior to machining to design size. An allowance is left in the sleeve for final machining to standard size.

In each of the above repair methods it is only the lower half bearing bore that requires attention in the case of a conventional bedplate and the upper half bore of the under-slung engine type.

The mating bearing caps can be reused, but more often than not, new bearing caps are advised and provided by the manufacture with the half bore having an allowance left on the diameter for final machining on assembly. Associated repairs and procedures allied to bedplate main bearing bore work would take the form of advanced metal stitching of heat induced cracking, milling of bearing cap fit location and possible make-up plating to remove fretting and wear.