The combustion zone of cutting-edge diesel engines has turned out to be progressively unfriendly with each new design. What’s more, outlines of cylinder crowns have turned out to be increasingly convoluted to give enhanced working properties and to battle higher combustion temperatures and pressures.
UES “Complete Overhaul System” is intended to give ship administrators prepared access to minimal effort and astounding reconditioned cylinders which are dimensionally and metallurgical proportional to new cylinder. Diverse cylinder sorts have distinctive disappointment qualities. UES reconditioning procedure includes point by point assessment to address every single basic region of the cylinder crown. UES can recondition motor parts of different diverse sorts of motors, for example, Sulzer RD/RND M/RND and RTA, MAN B&W GFCA and MC and Mitsubishi UEC.
UES reconditioning process for two-stroke piston crowns is as follows:
- Detailed pre-inspection of the piston.
- Pre-machining of the damaged crown top, worn ring grooves and other affected areas of the base metal.
- The build-up of material is done by an automatic submerged arc welding on a specially designed rotator.
- Stress relieving with the aid of a high-tech furnace.
- Final machining to specified dimensions.
- Hard chrome plating of piston ring grooves.
- Final grinding of piston ring grooves to OEM specifications.
- Pressure testing and detailed final inspection.
Four Stroke Piston Crowns
Four-stroke cylinder crowns are reconditioned by machining and grinding of ring grooves to next oversize.
Two Stroke Piston Crown
Disappointment qualities saw in the two stroke cylinder crowns include:
Excessive wear in the piston grooves – Piston grooves and outer diameter are rebuilt to standard measurements. The ring grooves are then hard chrome plated to a thickness coordinating OEM particulars
Internal & Topside Cracks -These fractures are distinguished before the reconditioning procedure starts and are evacuated and re-welded to stay away from untimely disappointment.
Crown Burning – All burning and harms are removed and developed to its unique stature and profile.
Chrome Plating of Two and Four Piston Crowns
UES has pioneered the chrome plating of piston ring grooves, which is presently utilized generally on each of the 2 stroke cylinders. UES ‘Chrome Grooving’ accomplishes huge results regarding diminished groove wear, future and unwavering quality.
Union Engineering & Supplies is a pioneer in the development of cost effective reconditioning techniques for both traditional plans and the most recent era of bore cooled cylinder covers in co-operation with OEMs and ship owners.
UES point by point assessment and Complete Overhaul System are intended to take parts back to unique measurements and resiliences to give a long and inconvenience free life. UES utilizes the “Calotte” strategy to recondition conventional B&W and Sulzer cast steel barrel covers.
Bore Cooled Cylinder Cover
Current bore cooled cylinder covers are produced from forged steel with cooling bores. Basic engine types incorporate MAN B&W, Sulzer and Mitsubishi. Disappointments amid operation can be created because of different issues, for example,
- Erosion and corrosion of air starting and safely valves
- Erosion & cracking in the area adjacent to fuel injector valves
- Cracking from the cooling bores due to chock-up of cooling water inside the bore
- Fretting of sealing faces and O-ring grooves.
Modern bore cooled MAN B&W, Sulzer and Mitsubishi covers can be reconditioned in a quick and cost effective manner to improve long term reliability of covers. DMI Dubai’s process involves the following steps:
- A detailed inspection of the cylinder cover, removal of cooling water shield (if required).
- Removal of the combustion face and cooling water bores. The remaining material is further inspected to ensure it is free of cracks.
- Welding of the combustion face, O-ring grooves and landing faces.
- Stress relieving under precise controlled conditions.
- Machining to specified dimensions.
- Re-drill the cooling water bores (if required).
- Machine spots adjacent to the fuel valve pockets, these spots are welded with a special nickel alloy (hard facing).
- Final machining.
- Final inspection including a hydraulic test and certification.
So as to withstand the great combustion temperatures produce in high-performance two-stroke diesel engine, the exhaust valves must be fabricated from exceptional combinations. The customary material utilized as a part of the production of 2-stroke debilitate valves is stainless steel with a stellite layer embedded into the seating face. Later era engines are fitted with exhaust valves made from solid nimonic material. The high material expense of exhaust valve axles and seats makes reconditioning an extremely alluring business recommendation gave that it is completed in a controlled way.
Exhaust Valve Spindles
The process for reconditioning exhaust valve spindles involves the following steps:
- Complete pre-inspection.
- Pre-machining of valve disc and seating area. Crack repair is done at this stage if required.
- Welding of the valve disc (upper and lower side) with suitable material using MIG welding equipment.
- Stelliting of seating area using plasma transferred arc process which ensures a high quality weld with minimum dilution of base material.
- Final machining and grinding to the OEM specifications.
- Stem treatment, if needed, by chrome plating or HVOF spray.
- Final inspection by certified QC department.
Exhaust Valve Seats
Union Engineering & Supplies is additionally ready to recondition exhaust valve seats for a wide range of engines. This is finished by evacuating the current stellite layer, developing seating range took after by re-stelliting, machining and granulating to unique profiles.
Exhaust Valve Housing
An exhaust valve housing holds the spindle in position and aides its movement. Extreme consumption on the interior surfaces of exhaust valve housing is brought about by the development of sulfuric acid because of the nearness of high sulfur fuel, high ambient, humidity and high exhaust gas temperatures.
Common failures observed in exhaust valve housing include:
- High erosion inside the exhaust valve housing
- Misalignment of spindle guide
- Cracks inside the exhaust valve housing chamber
The Al Musafi reconditioning process includes the following steps:
- Cleaning, pre-inspection and crack detection. We also use pressure testing to determine extent and exact location of crack if required.
- Machining or grinding the identified cracked area until clean & sound material is achieved.
- Pre-heating of component until optimum welding temperature is reached.
- Control heat input so that desired welding temperature is maintained.
- A carefully selected, self-manufactured filler material of the same grade as the base metal is fuse welded with the component.
- Cooling from fluid state to ambient temperature ensuring a stress free homogeneous weld repair.
- Machining or grinding of welded area to match the original profile.
- Re-bushing of spindle guide if found misaligned.
- Pressure testing of component to ensure no leaks are present.
Exhaust Valve Cages
Most exhaust valve cages are reconditioned for the accompanying imperfections:
Confines with harmed seats can have the seat face machined back to sound base material, developed and re-profiled. In this manner, the seating zone can be re-stellited and machined back to original measurements.
In the event of blocked internal cooling passages, it is conceivable to evacuate the whole nose and supplant it with new steel producing which is welded into spot utilizing complex Al Musafi weld forms.
Fusion Weld Repairs
Exhaust valve housings are normally made of cast iron which has a tendency to be more weak and less flexible posturing troubles in customary weld repairs.
UES reconditions exhaust valve housing with the assistance of an indigenously outlined fusion welding technique. Fusion welding of cast iron guarantees a homogeneous stretch free weld repair with enhanced metallurgical and machining properties contrasted with those of the parent metal. Materials to be welded here will quite often be dim solid metal. Dim cast iron has for all intents and purposes no malleability and is constantly weak. In the event that the powers of development or withdrawal, as produced amid the welding operation or in cooling post welding, are packed in one territory of the throwing, breaking of the throwing, or of the cooling weld, will probably happen. Consequently, at whatever point cast iron parts are welded, great precautionary measures is taken keeping in mind the end goal to accomplish a homogenous stretch free weld.
The Greater part of two stroke cylinder skirts have one or more bronze bearing groups in the cast iron body to give a perfect running surface against the barrel liner divider and to avert contact between the chamber liner and cylinder skirt.
In operation, these groups will, in the long run, wear out with the skirt body and can harm both the cylinder skirt and the cylinder liner which could bring about extreme seizure or splitting.
UES reconditioning procedure begins with cleaning the skirt and assessing for the nearness of any cracks that may bring about the dismissal of the cylinder skirt. In the event that the cylinder skirt is crack free then the accompanying strides are taken after:
- Removal of old bearing bands by machining
- New extruded bronze material is pressed in and locked in to the dovetail form of the groove.
- Machining to the correct diameter as specified by the OEM.
- A series of vertical grooves are then formed in each band to allow for radial expansion.
- Machining of seating faces to provide a true surface. In some of the engine types, cross hatching is also done on the piston skirts for oil grooves.
Contamination of the lubrication oil system and the high utilization of lubrication oil can be brought about by a well used out cylinder bar. UES reconditioning procedure takes the piston rod back to OEM determination without the need to fit undersized stuffing box rings. The reconditioning of piston rods includes making the surface of the cylinder rods wear safe in order to guarantee compelling burden limit and a long lifetime. Our procedure empowers cylinder rods for a wide range of 2-stroke engine to be completely reconditioned back to unique size rapidly and monetarily.
UES employs the following process to recondition piston rods:
- Cleaning, inspection, alignment control and crack detection.
- Pre-machining of the worn region to round and clean surface.
- Grit blasting of the pre-machined area.
- Metal spraying, welding or chrome plating (based on suitability) of piston rod.
- Stress relieving of welded area of piston rod (if required).
- Final grinding to OEM specifications and finish polishing.
- Re-facing of flange landings (if required).
- Final Inspection
In view of accessibility of undersized stuffing box, UES is likewise equipped for grinding a piston rod to the following accessible undersized. UES
UES reconditioning procedure for connecting rods is created to give ship owners, prepared access to minimal effort reconditioning.
Common defects observed in connecting rods include:
- Excessive ovality of big end bore
- Improper fit of connecting rod small end and its bushes
- Crack on serration area
- Loose small end bushes
- Damage to big end bore due to overheating, bolt or thread damage
Our reconditioning procedure includes point to point investigation to address every important area. All serration and bolts are checked for cracks. On the off chance that any cracks are found on these ranges then the bar is considered beyond repair. Rod and cap are then fixed according to OEM’s direction. Big-end bore is checked for ovality. In accordance with our QA and QC strategies, every one of the records is measured and reported.
The following is UES repair procedure:
- Grinding of serration on rod and cap side on milling machine, reducing the dimensions vertically and bringing the big end to oval shape.
- Rod and cap are assembled together and the mating faces are checked with blue paste, bolts are tightened to required torque as per OEM instructions.
- Grinding of parent bore to ensure proper alignment with respect to small end bore.
- Shrink-fitting of the small end bush
- Final inspection.
Cylinder liners serve as the inner mass of the cylinder and frame a sliding surface for cylinders while keeping up the suitable oil inside the chamber. It is critical to limit the wear on the cylinder liners thusly decreasing the wear on the cylinder rings and utilization of lubricants.
With the persistent operation of the engine, the chamber liner gets coated and gets to be oval prompting an absence of a cross to bring forth designs which refuse appropriate oil between the liner and cylinder. At Al Musafi the exactnesses of cylinder liners is kept up inside 0.02 – 0.03 mm for decrease/ovality and the surface complete and cross-sharpening point are achieved inside endorsed cutoff points of the OEM particulars. We are equipped with honing cylinder liners up to a bore size of up to 1 meter, in the workshop and insitu.
USE’s process involves the following steps:
- Pre-inspection to determine wear and damage and ensure it is within OEM wear limits.
- Honing of cylinder liners to desired surface roughness.
- Bring down the ovality (if any) within acceptable limit
- Final Inspection.
Four stroke cylinder heads are little and regularly made from cast iron. USE’s reconditioning procedure includes itemized assessment to address every single basic range of the cylinder head. Prior to any repair is done, we lead a pressure test to distinguish any spillages. Run of the standard engines that we recondition is Sulzer, Wartsila, Daihatsu, MAK, MAN B&W, Yanmar and SEMT Pielstick.
Common failure characteristics observed in four stroke cylinder heads include:
- Exhaust valve pocket leakage
- Highly corroded exhaust valve pocket
- Ovality in the exhaust and inlet pocket
- Misalignment of valve guides
- Cracks near the exhaust & inlet valve pockets
The reconditioning process for cylinder heads includes:
- Chemical cleaning to de-carbonize
- Grinding or renewal of seat rings and valve spindles.
- Renewal of valve guides and servicing of rotor caps.
- Machining of landing and combustion faces.
- Assembly, pressure testing and final inspection
Because of broad consumption on exhaust side pockets, they may have to be machined out to the following accessible oversize. Furthermore, ovality of exhaust valve pocket must be distinguished and extract. Since chamber heads are made of cast iron, any welding, if it is required, will be finished by fusion welding. Throughout the years we have watched that the utilization of fusion welding for crack repair on cylinder heads has accomplished preferable metallurgical and machining properties over those of parent materials.