Piston Crowns

The combustion area of modern diesel engines has become increasingly hostile with each new design. In addition, designs of piston crowns have become more and more complicated to provide improved operating properties and to combat higher combustion temperatures and pressures.

DMI Dubai's 'Total Reconditioning System' is designed to give ship operators ready access to low cost and high quality reconditioned pistons which are equivalent to a new piston in terms of metallurgy and dimensions. Different piston types have different failure characteristics. DMI Dubai is able to recondition engine components of major engine makes such as MAN, Wartsilla, Mitshubishi, UEC and Sulzar including their latest versions.

DMI Dubai’s reconditioning process for two-stroke piston crowns is as follows:

1. Detailed pre-inspection of piston.
2. Pre-machining of damaged crown top, worn ring grooves and other affected areas of the base metal.
3. Build-up of material is done by an automatic submerged arc welding on a specially designed rotator.
4. Stress relieving with the aid of a high-tech furnace.
5. Final machining to specified dimensions.
6. Hard chrome plating of piston ring grooves.
7. Final grinding of piston ring grooves to OEM specifications.
8. Pressure testing and detailed final inspection.

Two-Stroke Piston Crowns

Failure characteristics observed in the two-stroke piston crowns include:

Excessive wear in the piston grooves - Piston grooves and outer diameter are re-built to standard dimensions. The ring grooves are then hard chrome plated to a thickness matching OEM specifications.
Internal & Topside Cracks - These cracks are identified before the reconditioning process begins and are removed and re-welded to avoid premature failure.
Crown Burning - All burning and damages are removed and built-up to its original height and profile.