More efficient cutting, a longer operational lifetime, and lower energy consumption – that’s what Royal IHC’s latest cutter head technology for dredgers is all about. The Curve Tooth cutter head represents a major step forward in optimising the cutting process.
Article and pictures by Royal IHC.
Thanks to smart innovations, such as curved teeth and a cutter body cast in one single piece, this cutter head delivers superior performance, even in harsh conditions. Successful tests conducted by the Suez Canal Authority confirm that this technology doesn’t just work in theory, but delivers immediate results in practice. A breakthrough resulting from years of research and development.
The cutter head, which enables Royal IHC to increase its range from approximately 1500 kW to 6000 kW or higher, has been added to the portfolio following successful trials with a 4800-kW model by the Suez Canal Authority.
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Teeth: key innovation
The main innovations in the new cutter head, on which Royal IHC has been working for ten years, can be seen in the teeth and in the head itself. The head is cast as a single piece, which is unique in the market. Three patents have, however, been obtained for the greatest innovation: the teeth. One of the patents relates to the tooth’s curvature, including that of the tail, hence the series name: Curve Tooth cutter head.
‘The idea for the curved tooth comes from a type of sea snail that uses a similar principle to loosen up food firmly attached to rocks,’ explain Hasan Bugdayci, MSc, Product Manager Excavation Equipment & Dredge Pumps, and Rick van de Wetering, Research Engineer at Royal IHC’s Technology Department. ‘Credit for this brainwave goes to the University of Groningen in the Netherlands, which researched this at the request of Boskalis.’
They add: ‘The sea snail’s curved tooth is highly resistant to forces generated while scraping rock. Its natural curvature ensures stresses are distributed more effectively than with a straight tooth. As a result, the cutting edge of a curved tooth can be smaller without compromising strength. A curved tooth is sharper and more effective. Because this effect remains consistent, a curved tooth remains sharper than a straight tooth for its entire lifespan.’
‘You can’t suction anything without cutting it first. Our new cutter head represents a big leap forward in this respect. It even performs extremely well in sticky soil, even though the curved pick point wasn’t initially designed with this in mind,’ says Bugdayci. The Curve Tooth cutter head can be fitted with different types of chisels: the pick point (as used in the Suez Canal), a narrow chisel, or a flared chisel.
Hammerless locking mechanism
The two other patents that Royal IHC has obtained on the cutter head are related to the design of the way in which tooth and adapter interlock, Bugdayci and Van de Wetering explain. ‘The fit between tooth and adapter must be very precise to minimise wear and tear on the adapter. As a result of forces, the adapter loses its shape – so-called “hammering”. Slack exacerbates this. A tooth lasts 45 minutes at most, but the adapter has to last up to a hundred teeth.’
Bugdayci: ‘Our completely new locking mechanism design is “hammerless”. It eliminates the traditional, hazardous system in which two men drive a pin between the tooth and the adapter. Our invention ensures constant, play-free, exceptionally tight contact thanks to a mechanical spring. This locking system allows the tooth to be replaced more quickly by just one person.’
A one-piece head
In addition to the three patents, this new cutter head has two other important features: the new material of the teeth and the casting of the cutter body in a single piece. Casting the entire head in one piece, no matter how complex, results in a stronger head.
‘That wasn’t even the main goal – we were aiming for freedom of shape, strength, and increased durability. When the back ring, six arms, and hub are all welded together, which is what the competition does, residual stresses arise after the welds cool down—resulting in potential weak points,’ says Bugdayci.
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New, lighter tooth material
A new material for teeth has been developed in collaboration with a partner foundry in Germany that specialises in dry mining. The adapters for the new cutter head are also cast there.
‘For years, we have been working with this partner to find the best alloy to withstand wear and impact of forces,’ says Dennis Kweldam, Product Specialist for cutter heads at Dredging Equipment, who oversees the project’s technical aspects.
The new tooth is over ten per cent lighter than that of the main competitor, while its cutting and wear volume is fractionally larger. This is the result of two design choices: the organic curvature of the tooth and the way it is mounted inside the adapter rather than over it. The result is a lighter system that discards less tooth material. This is not only a financial advantage, but also beneficial in terms of handling and our environment.
Ongoing development
As of February 2025, the current situation follows an exhaustive yet challenging development process spanning some ten years of simulations, laboratory tests, cutting trials, design, modelling, small-scale prototypes, full-scale prototypes, tests, and experiments, culminating in full-size field tests with the Suez Canal Authority. However, the fact that the Curve Tooth cutter head is now in place by no means implies the project is over. Innovation never stops.
Van de Wetering states: ‘Translating university research results into practical solutions is the power of the future. That’s innovation.’
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Less spillage, better cutting
‘Whatever you spill, you’ve lost – and that can easily add up to thirty per cent. We’re now investigating how to reduce spillage,’ says Engineer Thijs Schouten from Dredging Equipment. “Low Spill” is the project’s working title.
Schouten: ‘We will mainly focus on design flexibility for the cutter body, the major advantage of casting in one piece, and simulate how this can be improved. We don’t want to rely on guesswork, but rather reduce spillage in a targeted manner. We will study the spherical shape of the head, the contour, as well as the teeth, their angle, number, and the optimal spacing between them. There is still much to be gained in terms of reducing spillage.’
Dynamic cutting process
Van de Wetering remains closely involved in the research into “low spill”, partly through his PhD project. He is now specifically focusing on the cutting process. ‘The influence of dynamics during the cutting of rock is not frequently studied in the literature, even though it may play a significant role. I will investigate these influences theoretically and experimentally during my PhD.’
He adds: ‘Due to its complexity, the cutting process is often considered and studied as rigid and continuous, whereas in practice it is very dynamic.’
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No one size fits all solution
Kweldam: ‘We have developed the entire system of innovations for a single capacity – 4800 kW of installed power – and for rock. The next step is to meet market demand below and above that capacity. This could also include a 12,000-kW system for the very large cutter suction dredgers, such as the Spartacus, which require this for working with sand.’
‘We will not simply scale the cutter head for new projects involving a Curve Tooth cutter head at a power level other than 4800 kW,’ says Kweldam firmly. ‘We are working towards a total package intended for a specific soil type, it will never be a “one size fits all” solution. This is where the modular system comes in handy, allowing for switching to different teeth. The two types of chisels (narrow and flared) are, of course, also “curved”. For sand, gravel, and clay, you need to look for a head shape that suits the specific soil type. And this is where casting in a single piece proves useful once again.’
Picture (top): A decade of research at Royal IHC leads to an innovative cutter head for even the largest dredgers (photo by Royal IHC).
