Five In-Situ Machining Jobs on Large Two-Stroke Engines in Three Months

At QuantiServ, we are dedicated to providing exceptional in-situ machining services to the maritime industry.

Over the past three months, our team has successfully completed five significant crankpin machining assignments on large two-stroke marine main engines. These projects, carried out on four different engine types built by the two market-leading OEMs, highlight our versatility and expertise.

Project Highlights

  • North America: We performed extensive crankpin machining on a container vessel, ensuring the engine’s optimal performance and reliability. Almost simultenously, we also worked on a bulk carrier, deliverig high-quality crankshaft machining services that meet the stringent standards of the maritime industry.
  • The Caribbean: Our team tackled a challenging crankpin machining job on an oil tanker, restoring the crankshaft to its full operational capacity in less than two weeks.
  • North Asia: On a Ro-Ro ship, we executed a complex crankpin machining task, demonstrating our ability to handle diverse vessel types with ease.
  • South East Asia: Another successful project involved a gas tanker, where our team ensured the engine’s reliability and efficiency through crankpin machining and other repair works.
One of the crankpins undergoing repair
One of the crankpins undergoing repair

In all these cases, we worked on crankpins from Ø 600 to 900 mm and machined off anywhere from 4 mm to 10 mm, due to excessive hardness and cracks following a bearing failure. Typically the repair work involves machining and then machine polishing of the cylindrical crankpin surface and of the fillets1. On some of these vessels our specialists worked in a single-shift modus, while on others they worked around the clock in two shifts. It always depends on the customer’s wishes and on her operational requirements.

*The fillets are the radial undercuts at the transition of the crankpin to the crank web.

One of the crankpins prior to repair
One of the crankpins prior to repair
After machining and polishing
The same crankpin after machining and polishing

Comprehensive Services

In addition to the crankpin machining work, we also provided a range of related services, including:

  • Planning: Remotely assisting the customer to find the best repair solution  and to make arrangements before the vessel even reaches the location where the repair is to be carried out.
  • Sourcing of Under-Size Bearings: : Ensuring the availability of tailor-made bearings, with short lead time. Under-size bearings have a thicker white metal layer and are usually not available off-the-shelf. They have to be produced on a case-by-case basis. Some of these bearings we produce in-house, others we source from specialized manufacturers.
  • Reconditioning of Engine Components: Extending the life and performance of critical engine parts in one of our four reconditioning centres.
  • Other Repair Works: Addressing various repair needs not related to the crankshaft, ensuring comprehensive engine maintenance.

Commitment to Excellence

Each of these projects underscores our dedication to providing reliable and efficient in-situ machining services. Our ability to mobilize almost instanteneously and to perform these tasks on-site in a 24/7 manner, saves our clients valuable time and limits loss of income. Whether it’s a container vessel, tanker, Ro-Ro ship, bulk carrier, or gas tanker, QuantiServ is equipped to handle the unique challenges of each job with precision and professionalism.

We look forward to continuing our tradition of excellence and supporting the maritime industry with our specialized in-situ machining services.

Crankpin machining whereby the cutting tool moves in a continous orbital path around the crankpin, resulting in uniform material removal
Crankpin machining whereby the cutting tool moves in a continous orbital path around the crankpin, resulting in uniform material removal
Blueing test to verify that the bearing shell makes full and even contact with the crank pin.
Final blueing test to verify that no high spots are present and that the bearing shell makes full and even contact with the crankpin

Note: All photos in this post originate from the five projects, they are not depicting the same project.

Crankpin Grinding in 18 Hours, Between Christmas and New Year

True to our credo of “whenever, wherever”, our in-situ machining specialists in Singapore completed a repair assignment during the final days of 2021 in just 18 hours.

At 22:00 on 29 December 2021, at a time when most people traditionally enjoy seasonal festivities and spend time with their loved ones, they boarded the ship with just a few hours notice. The vessel, a German-owned 4200 TEU box ship had arrived in Singapore 9.5 hours earlier and was now waiting for them on anchorage. Once our specialists were on board, the vessel proceeded to the terminal while our colleagues immediately went to work on one of the three Japanese-made auxiliary engines. This engine had suffered a crankpin failure on one of its units.

The engine is equipped with a hardened crankshaft. This means that the crankpin could not be machined but had to be ground. Through the night, our two specialists ground the pin from 260.00 mm to 259.50 mm so that the first undersize bearing can be fitted.

In-situ crankpin grinding
In-situ crankpin grinding

At regular intervals during and after the grinding and subsequent polishing work, our two in-situ specialists verified the dimensional accuracy and the hardness of the pin. The final hardness was measured to be 625 HB, which is a very good value. And for final verification, our specialists also checked the contact area on the completed pin. For this, they used a specially manufactured template and engineering blue.

Our specialists completed their work and disembarked from the vessel at 16:00 on 30 December 2021. It took them just 18 hours to repair the crankshaft!

Fifty minutes later, after the completion of cargo operations, the vessel left Singapore for China. The ship crew will install the new – 0.50 mm undersize bearing shells once they arrive on board and will then restart the engine.

Verifying the contact area on the completed crankpin
Verifying the contact area on the completed crankpin
Surface roughness measurement on the completed crankpin
Final surface roughness measurement