In-situ Machining the World’s Largest Four-Stroke Diesel Engines

Ø 64 cm bore, 90 cm stroke, 2’150 kW (2’880 hp) power per cylinder: The world’s largest four-stroke engines are very mighty machines indeed!

These powerful engines were built during the late 1990’s, mostly in a 6-cylinder configuration. With a nominal power output of 12’900 kW, they found popular application as single propulsion engines in multi-purpose cargo vessel of about 20’000 DWT size.

During 20 – 25 years of operation until now, these engines have accumulated more than 120’000 running hours each. In terms of number of engine revolutions, this is equivalent to a car driving for 1.8 million kilometers (1 million miles)!

In-situ crankpin polishing
In-situ crankpin polishing

It is therefore hardly surprising, that after that many running hours signs of wear were found on the crankpins of these engines. As is often the case on medium-speed, four-stroke engines, the crankpins were suffering from what is called “cam effect” or “ridge wear”.

Has your four-stroke engine accumulated around 60,000 running hours or more?

Although the crankpins might appear to be in good condition, it is very likely that they suffer from the cam effect (also known as ridge wear) and are in need of machine polishing. If this is not done, then you might face a failure soon!

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Usually, then the cam effect will manifest itself in two ways:

  1. Through uneven wear in horizontal direction, with nearly no wear at the centre of the pin and at the edges, but with easily noticeable wear to the left and right of the oil bore.
  2. The pin is not affected evenly throughout its circumference. The cam effect is usually most pronounced at about 30 – 45 degrees after Bottom Dead Centre (BDC). For this reason it is called “cam effect” – the pin is not perfectly circular anymore.

QuantiServ appeals to owners and operators of medium-speed four-stroke engines to sensitize the crew about the cam effect. We highly recommend that the pins are carefully checked whenever an engine overhaul or bearing replacement is carried out. If any uneven wear patterns are detected, then the pin must be machine-polished to restore its proper geometry before any new bearings are installed and the engine is restarted.

If the cam effect is detected in good time, then machine polishing of the pins is usually sufficient to correct the problem. After machine polishing, the crankshaft will be ready again for several years of continuing operation. Whether standard bearings or undersize bearings will have to be installed after polishing will depend on the actual situation.

If, on the other hand, the cam effect goes undetected for too long, then a crankpin failure is almost inevitable. Such was also the case here on the first engine. Heat treatment and machining was therefore necessary and was swiftly carried out by our Swedish specialists. Having seen the excellent result and now aware of the cam effect, the customer tasked us to machine polish all pins on this engine and on the sister vessels, which is why we eventually polished about 70 pins in quick succession but in different ports.

In-situ heat treatment
In-situ heat treatment (annealing)
Crankpin machining
Crankpin machining
Completed crank pin
Completed crank pin

All work described above was carried out on board by our Swedish in-situ specialists. They were supported by our reconditioning experts that meanwhile worked on those engine components that were removed from the vessel for an intervention ashore. These components were sent to our reconditioning centre in Kruiningen, The Netherlands, where they underwent  thorough overhauling and machining works.

By the time of writing in August 2022, we have overhauled around 70 cylinder heads and have re-bored a similar quantity of big end bearing housings. Machining the big end bearing housings became a necessity due to excessive ovality in the bore.

Newly overhauled cylinder heads in our workshop
Newly overhauled cylinder heads in our workshop
Big end bearing bore machining
Big end bearing bore machining

Comprehensive Repairs: We Succeed Where Others Fail

Example of a Comprehensive Crankshaft Repair Assignment, Started and Then Abandoned by a Competitor

During the last days of 2020, our in-situ repair specialists out of Gothenburg, Sweden, repaired a damaged crankpin on a Korean-made four-stroke engine. The engine has a 32 cm bore and a 40 cm stroke and is installed on a 5 year old, 9’200 TEU container vessel.

When contacted by the ship owner, we proposed to carry out an inspection on board. The shipowner agreed, whereafter our specialist from QuantiServ Panama carried out a thorough inspection in Panama. To our disappointment, the ship owner then awarded the repair work to another company. Their technicians machined the pin to – 0.80 mm undersize and then gave up and disembarked from the vessel.

Finding himself in a tight spot, the customer came back to us and asked us if we could continue the repair that was abandoned by the other company. We took the opportunity to demonstrate that we succeed where others fail. Two in-situ specialists from QuantiServ Sweden joined the vessel and successfully carried out the repair work while  underway from Lima, Peru to Manzanillo, Mexico. They solved the problems as follows:

Issue Action taken Result
Damaged surface and cracks Machining Crankpin under-sized to – 3.00 mm
Excessive hardness Heat treatment (Annealing) Hardness Reduced from 620 HB to 255 HB
Bent crankshaft Peening Run-out reduced from 0.27 mm to 0.03 mm

The customer was very happy with the skills and performance of our specialists. He therefore kept them on board for subsequent reassembly and overhaul works and he also asked us to supervise an  overhaul of a similar engine installed on a sister vessel.

Jaw Crusher In-situ Machining, 700 Meters Underground

In November 2018, our in-situ specialists carried out machining work in one of the world’s most modern underground mines, located in central Sweden. The mine processes about 2.5 million tones of ore annually and produces gold, silver, zinc and lead.

The assignment lasted about a week and consisted of milling, drilling and tapping work on a large jaw crusher located at a depth of 700 meters. There, the ore is crushed before it is hoisted to the surface for further processing.

Our specialists machined the upper section of both the stationary and the moving jaw. On each jaw, they milled off about 26,000 cm3 of steel and then drilled and tapped them so that a newly fabricated section could be bolted on.

QuantiServ’s In-situ Machining Specialists are Very Highly Trained

The last few weeks have been a busy period for our internal trainers at our in-situ training center in Gothenburg, Sweden. Courses were scheduled back to back. In-situ machining colleagues from around the world were undergoing refresher training on a variety of topics: in-situ crankpin machining, in-situ heat treatment (annealing), engine block machining, etc.

At QuantiServ, we very highly value formal training. All our in-situ machining specialists undergo rigorous training and assessment when they first start to work for us. And it does not stop there. As we constantly keep on further developing and improving our tools and processes, we regularly call the in-situ machining specialists that normally are stationed all around the world back to our in-situ training centre in Sweden to equip them with the most updated skills and knowledge.

This was the case with colleagues from Italy and Brazil that joined a training course last month. Even though some of them already work for us for ten years or more, there are always new tricks that they can pick up. A lot of knowledge sharing and networking takes place during these courses too. The trainees meet with our designers and tool developers and provide them with valuable feed-back and experience from the field. This information then flows into the next generation of tools so they become ever better and more efficient. It is highly trained machinists and cutting edge tools that keep QuantiServ at the forefront of the in-situ machining industry.

Crankpin machining training

Crankpin machining training

Crankpin machining training

Crankpin machining training

 

 

 

 

 

 

 

 

In-situ heat treatment training

In-situ heat treatment training

In-situ machining specialists from Italy

In-situ machining specialists from Italy

 

 

 

 

 

 

 

 

Our Brazilian colleagues proudly showing off their renewed certification. Notice the quality of the pin surface.

Our Brazilian colleagues proudly showing off their renewed certification. Notice the quality of the pin surface.

 

 

 

 

 

 

It’s All in a Month’s Work for QuantiServ’s In-situ Machining Crew!

On board various ships and oil rigs, in power plants and in factories: Far from being idle during the holiday season, during the month of July our in-situ specialists were maintaining and repairing our customers’ equipment in 26 different countries, across four continents. No other in-situ machining company has such global reach and completes more projects than QuantiServ. Wherever the location, whatever the damage – it’s all in a month’s work for us!

Explore the interactive map below and discover what services our in-situ engineers have been providing to our customers during the month of July 2017.