Line boring belongs to the type of assignment that we take on very frequently. We are used to work on a very wide range of equipment and locations. Our engineers and machinists are very experienced and able to bore virtually any cylindrical or tapered inner diameter, be that a Ø 50 mm coupling bolt hole or a Ø 1000 mm stern tube bore with a stepped inner diameter.

The maximum length that we are able to bore is around 10 meters, which means that we can work on nearly any type of equipment, including but not limited to two- or four-stroke engines, turbine casings, stern tubes and rudder stocks.

Because there are no line boring machines as versatile, accurate and efficient as we require them available in the market, we design and build them ourselves. These tools are very advanced and very compact, to reduce freight costs and to be able to work in very tight places.

Line boring
Line boring of the main engine pockets on a four-stroke diesel engine

When line boring bearing pockets, two methods exist. One is to first remove material at the mating faces of the upper and lower bearing housing. By so doing, the bore becomes elliptic. It can then be machined and standard bearings may be fitted. The main drawback of this method is that it is usually not possible to achieve 100% contact between the back of the bearing shell and the housing. Almost inevitably, no contact will be possible at the 3 and 9 o’clock positions.

For this reason, boring the pockets to over-size is usually preferable, although that means that standard bearings cannot be fitted anymore. Instead, over-size bearings will be needed. Such bearings have a larger outside diameter as compared to standard ones. Thanks to our good relationship with leading bearing manufacturers, we are usually able to supply such bearings on short notice.

In addition to the line boring per se, we also provide a lot of related services such as

  • to supply and install repair sleeves and bushings, for example to the engine block around the cylinder liners
  • to build up worn shafts, depending on the application and damage either by welding, metal-spraying, chromium plating or by installing a repair bush
  • to machine key ways
  • to skim landing surfaces
  • reaming of bores such as those for shaft line coupling bolts
  • in-situ honing of inner and outer diameters

We  always check and adjust the accuracy of our machining activities by laser. In some cases the lasers are even built into our machines.

Line boring tool with integrated lasers
Line boring tool with integrated lasers
Line boring of a stern tube bore while the vessel is afloat
Line boring of a stern tube bore while the vessel is afloat

Image Gallery

Line boring of an engine block on board
Machining the main bearing pockets of an engine block on board
The inner bore of a stern tube is usually stepped to reduce the risk of seizure during installation of the bushes
The inner bore of a stern tube is usually stepped
Line boring of an engine block in the shipyard workshop
Line boring of an engine block in the shipyard workshop
Four-stroke engine block raised above the foundation for machining
Four-stroke engine block raised above the foundation for machining
Line boring of a bed plate on board
Line boring of an auxiliary engine bed plate on board
Line boring of a four-stroke engine block in a power plant
Line boring of a four-stroke engine block in a power plant