Production has officially begun at MAN Truck & Bus’s Nuremberg plant for a new ultra-efficient 13-litre diesel engine, developed as part of a joint engine platform for use across the group. Playing a key role in this advanced production process are fine boring tools from MAPAL, which are used to machine the cylinder heads, specifically for valve guide and valve seat blind bores.
Almost simultaneously, MAN has launched two major projects for the future at the Nuremberg site. Alongside the start of diesel engine production, battery series production for the company’s electric vehicles has also gone into operation. The facility is designed to produce up to 50,000 batteries annually at more than 50 assembly stations, with the flexibility to expand production capacity to 100,000 high-voltage batteries by 2030.
The new battery production building is an impressive structure, standing over 35 metres tall and recognized as the tallest production building on the Nuremberg site. Directly opposite, diesel engine production takes place across a sprawling area of 23,000 square metres.
As process planner, Marco Singer is responsible for overseeing production of the cylinder heads for the newly developed D30 engine, designed entirely from the ground up. The state-of-the-art battery production facility is located directly opposite hall M17, marking a significant step forward in MAN’s dual commitment to advancing both traditional and electric powertrain technologies. Marco Singer describes the transformation to the electric drive as follows: “The electric motor is the ideal drive for a wide range of applications, such as city traffic. In other areas, however, diesel will continue to exist for a long time to come.” Examples he gives include uses in agriculture, the navy or the armed forces. A mix of different drive technologies will therefore be required for the future.
An Engine for All Brands
The Traton Group—which includes MAN, Scania, Volkswagen Truck & Bus, and International Motors—relies on the Traton Modular System (TMS), with components designed for use across its brands. This approach enables the group to pool resources efficiently, true to the motto: “you don’t need to reinvent the wheel.”
At the heart of this system is the D30 engine, developed as a joint engine platform for the entire group. From development and mechanical production to engine assembly and delivery to vehicle manufacturers, every stage takes place at MAN’s Nuremberg site, which even housed its own foundry until three years ago.
Although based on a single platform, the D30 is produced in six different performance levels, ranging from 360 to 560 HP. It is the largest standard engine in the Traton portfolio, designed primarily for use in heavy-duty 40-ton trucks.
The D30 replaces the earlier D26 and D15 engine series and sets new benchmarks in efficiency. Achieving a maximum efficiency of 50%, it consumes 5% less fuel than its predecessors, leading to a corresponding reduction in CO₂ emissions.
MAN Invests €220 Million in New Engine Production
MAN has invested around €220 million in the production of its new engine, where up to 160 highly qualified employees will eventually work in three-shift operations. The technical capacity at the Nuremberg plant allows for the production of approximately 50,000 engines annually. “The actual production volume is based on demand. Whether this is used to its full potential is ultimately decided by the customers,” explains process planner Marco Singer. In recent years, customer demand has been somewhat reserved, with discussions around the transition to electric drive creating uncertainty for commercial vehicles as well as passenger cars. For now, production will begin with a single shift.
MAN has maintained a long-standing partnership with MAPAL, and when tendering for the D30 project took place in 2019, the Aalen-based tool specialist once again secured the contract. MAPAL was chosen to provide the fine machining tools for valve guide and valve seat bores, thanks to decades of collaboration and a recommendation from machinery manufacturer Grob, which oversees the complete process and tool design.
The six-cylinder D30 engine features two inlet and two outlet valves per cylinder, requiring 24 bores to be drilled into each cylinder head bank. As the inlet and outlet diameters differ, multiple tool sizes are needed for machining. This precision work is performed on a double-spindle machine, integrated within a linked system of Grob machines, which are loaded efficiently using linear gantries.
Proven technology produces reliable process
A further tool manufacturer was entrusted with fine machining in the project’s initial phase. As a stable and cost-efficient process was not possible with its tools, however, MAN ultimately shifted its full focus to the collaboration with MAPAL. The Aalen-based company’s first contribution was a fine machining system which has run on many machines in two production halls at MAN for many years. In close coordination with the client, however, the partners continued to develop the system and achieved significant progress.
Singer hails the achievements: “The machining changed fundamentally. For instance, we saved a semi-cut and were able to do without pilot friction. Instead, we simply moved to our pre-machined diameters with the indexable insert tool, ensured a good bore entrance for the reamer, and then ultimately reamed through once. Experience helped us design the process in the best possible way.” The production concept achieved a good machining quality and complied with the specified cycle time of around five minutes in total for fine machining of the valve seat and valve guide. The desired reliable and economical process was achieved. “This was accomplished despite the increased quality requirements for manufacturing the new engine”, says Markus Meyer, who works closely with MAN as a technical consultant at MAPAL. For the valve and both valve seat blind bores, the tolerances are less than 20 µm. A tolerance of approximately 50 µm must be maintained from the seat to the guide. There must be no offset between the valve seat and the valve guide that could lead to undesirable shear forces. The surface finishes required are specified at an Rz of less than 20 µm. The cylinder head bank consists of GJV 450 cast iron into which more wear-resistant materials for the valves are pressed in the form of a ring and a guide.
Modern technology reduces unit costs further
However, a series of joint workshops had further improvements in its sights, particularly with regard to unit costs. The aim was to reduce them further before series production began. MAPAL and MAN achieved significant improvements together through their professional partnership.
Simplifying tool handling provided the necessary leverage to lower costs per part – specifically the reduction of configuration time, making things simpler for the operator. For this purpose, MAPAL brought its EA (EasyAdjust) system into play. It was installed for the valve seat tool. In this system, the back taper on the blade is already integrated into the cassette, which acts as the connection for the insert. This feature completely eliminates the need to set the back taper on the minor cutting edge. Only the diameter needs to be adjusted. Thomas Teuber, Head of Product and Application Management Fineboring at MAPAL, summarises the practical benefit: “The operator no longer needs to keep an eye on two dial gauges. They can focus on just one dial gauge, which they can use to adjust the insert’s protrusion compared to the guide pads. That’s much faster.” The EA system also involves an improvement in the inserts: The TEC indexable inserts used in the EA system have four cutting edges, i.e. twice as many as a conventional MAPAL reaming inserts. An optimised cutting material and innovative coating increase tool life and ensure an even more reliable process.
The modifications proved effective: In comparison to the original machining concept, valve seat and valve guide machining costs were reduced by around 40%. “I’m very happy with the milestone that has been achieved”, says Singer, singling out the effective partnership with MAPAL for praise. The ambitious process planner aims to keep pushing forward with the continuous process of improvement.The assumption at MAN is that the D30 will be the company’s last entirely newly developed diesel commercial vehicle engine – after over 100 years of diesel engine construction at the Nuremberg site. As of 2030, every second vehicle delivered to customers should have an emissions-free drive.
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