A Frenchman and the crazy Dutchman – nothing is impossible
"Sometimes people thought we were both crazy," jokes Joop Nijland as he talks about his experiences. Together with HORN technician Roger Kasper, Nijland has spent the last 30 years devising tool solutions that have left many people shaking their heads. His expertise in tricky tool solutions earned him the nickname "the crazy Dutchman". One of these solutions can be seen in the milling of a round thread used in shipbuilding at Kooiman Marine Group, near Rotterdam. Milling the thread having a diameter of 400 mm (15.748") and a pitch of 40 mm (1.574") increased production quality and led to significant time savings.
In three decades of working together, Kasper and Nijland developed complex tool solutions, some of which are unrivalled. From initial sketchy ideas to complex multi-stage tool systems, they demonstrated the ability to turn technical challenges into workable solutions. "Sometimes people shook their heads when we proposed our ideas. However, the HORN designers almost always turn them into functioning tools," says Kasper. Nijland adds: "Without the design department at HORN, our ideas would often have come to nothing. They do a very good job."
Tricky milling task
Nijland previously worked as a technical sales representative for the Dutch HORN agency Harry Hersbach. Kasper, on the other hand, was his contact at HORN, responsible for technical consultancy for France and the Benelux countries. One of their most recent major projects concerned the milling of threads having a round profile. Turning was not possible due to the component geometry. The threads have 32 mm (1.259") and 40 mm (1.574") pitches and diameters ranging from 400 mm (15.748") to 500 mm (19.685"). The depth and width of the individual threads are around 40 mm (1.574"). The thread is subjected to high tensile loads during use. Accordingly, the quality requirements are high and the tolerances tight. Nijland and Kasper set themselves the task of milling the thread in a single cut.
"The crazy Dutchman has another wild idea. That was the first reaction of the designers in the technical office," laughs Kasper. On closer inspection, the idea in CAD grew into a finished tool solution. Simply put, the milling cutter has six teeth or cutting levels having a diameter of 300 mm (11.811"). However, each of the six teeth consists of several individual cutting edges with different profiles. They produce the desired thread profile in a single pass. HORN uses indexable inserts of types S279 and 409 for this. The double-edged type 279 inserts are precision-ground to a special shape to mill the thread radii. Type 409 inserts from HORN's standard portfolio support the process by providing efficient metal removal from other areas of the thread.
High milling performance
Due to the high surface finish requirements, the Kooiman team split the machining into two cuts. The tool mills the round thread profile at a cutting speed of 220 m/min (721.785 ft/min), with a finishing allowance of 2 mm (0.079”). Finishing is carried out at a cutting speed of 280 m/min (918.635 ft/min). Tool life is three finished threads per cutting edge. Machining time for both operations is around three hours. The milling process is dry. "We are delighted with how the tool performs. Compared to the previous machining process, the quality is much higher," says Kooiman Production Manager Lawrence Kooij.
Round threads transmit high forces thanks to even load distribution and precise thread engagement. The cylindrical geometry and continuous threads create a larger contact area, which minimises stress concentrations and improves load absorption. The uniform application of forces along the thread contour increases load-bearing capacity and rigidity, while reducing torsion and bending stress. Round threads enable high bolt and nut stiffness, reduced play and secure fastening over long engagement lengths. This is a particular advantage in vibration- or safety-critical applications.
Large parts, large machines
Anyone who produces large parts needs machines of appropriate size. Kooiman recently invested in a machining centre from Retos. The RETOS RET10P is a powerful universal milling/turning platform for the precision machining of large components. It combines a robust structure, high rigidity and modern CNC technology to reliably produce complex components. With its precise kinematics, the machine achieves excellent repeatability. High clamping force, low-vibration machining, integrated tool changing and minimal set-up times are outstanding features.
Repair and new ships
The Kooiman Marine Group offers a comprehensive portfolio of services along the entire value chain for ships and offshore installations. From engineering, design and manufacturing to maintenance, repair and retrofit, the company covers core competences such as mechanical production, marine equipment, propulsion technology, construction services and repair and spare parts management. Comprehensive solutions include project management, quality and safety management, logistical coordination and around-the-clock technical support. Customers benefit from customised, efficient and reliable services that combine global standards with local requirements and take sustainable practices into account.
In addition, the Group offers integrated services with a focus on reliability, availability and optimisation of operating costs. This includes comprehensive maintenance, modernisation and retrofitting of existing fleets, customised maintenance contracts, spare parts strategies and flexible logistics and procurement offers. Through lean processes, quality assurance to high standards and close cooperation with customers, the Kooiman Marine Group delivers long-lasting solutions, reduces downtime and ensures operational efficiency throughout the entire life cycle of the vessels.
Work turned into friendship
The decades of collaboration also resulted in a close friendship between Kasper and Nijland that grew beyond professional boundaries. Shared travel and extensive debriefing sessions in hotels created a foundation for reliability and respect. There was never an issue that they could not resolve together, nor a conflict that could not be overcome through open dialogue and a solution-oriented approach. This connection made the collaboration not only productive but also fulfilling, as friendship and profession merged. Now both are retiring at the same time. "Now it's the turn of the youngsters, who are already motivated and waiting in the wings," says Nijland.
In summary, the long-standing collaboration between Kasper and Nijland shows how creative tool solutions can significantly increase production quality. The joint development of HORN's round thread milling system achieves long tool life and short machining times. Over three decades, ideas have been successfully implemented, trust has been built up and ultimately a close friendship has been forged. Not only has the Kooiman Marine Group benefited from this duo, but numerous other customers as well.