Maprom NCB Hard coated Liners

Rock-Solid Guarantee

MAPROM NCB (Nickel-Chromium-Boron) hard coated liners are guaranteed to double the life of shafts made of conventional materials such as stainless- or carbon steel, but even 4 or 5 times longer shaft-life may be possible.

NCB liners with a 58 to 62 HRc (hardness) also increase service wear life of shafts and shaft sleeves where mechanical abrasion and corrosion takes place, like seals, packing, and bearing areas.

Maprom NCB Shaft Sleeves can provide maximum protection for rudder stock and tail shafts. The fused area of the shaft sleeve is undercut. The undercut area is then thermal coated with the Nickel-Chrome-Boron powder using multiple spraying passes, the sleeve is hard-coated to an oversized dimension. A heat treating process is used to fuse or metallurgically bond the NCB hard coating to the base material at a very high temperature. After cooling, the shaft sleeve is ground to a 6-8 RMS finish and provides a 58-62 HRc.

Propeller shaft design

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Finished Bore or Rough Bore

Maprom NCB Liners can be supplied with a “Finished Bore” or “Rough Bore”.

  • Finished Bore: Dimensions are supplied ready to shrink fit installation to the shaft and do not require machining of the sleeve bore diameter prior to installation. This requires the customer to provide shaft diameter dimensions so correct shrink fit and the finished bore dimensions can be calculated at the time the shaft sleeve is manufactured.
  • Rough Bore: When shaft dimensions are not readily available, or the shaft needs to be modified or repaired at dry docking, rough bore sizes can be supplied. Rough bore sleeves are supplied with an undersized bore diameter and requires a finish boring operation prior to installation.

In addition to shaft liner applications for fresh water, there is a sea water resistant range from 316L base material. Alternatively GFR-epoxy lockingrims can be supplied at liner ends for “phillyclad” applications.

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Owners of a wide array of different vessels choose the high quality solutions Maprom Engineering provides: