Precision manufacturing of forming tools

Forming tools for gearbox housings, such as those used in the automotive industry, must withstand high mechanical stresses. They must allow sheet metal or blanks to be easily formed without producing chips. Therefore, in tool and die making, the quality of the tools used in the roughing and finishing processes is critical to the final quality of the workpieces. High-alloy tool steels are used – and this places high demands on the milling tool, cutting material, and machining strategy alike.

Machining Hardened Materials: High-alloy tool steels require a precisely coordinated combination of cutting material, geometry, and process control in mould and die. Without this coordination, there is a risk of tool wear, chipping of cutting edges, and costly scrap parts.

Highest Surface Quality: Forming tools transfer their surface finish directly to the workpiece – any irregularity on the tool surface will later be visible in the component. Finishing and semi-finishing must therefore proceed precisely in tandem.

Complex 3D contours: Deep cavities, tight radii, and free-form areas—the geometry of a transmission housing requires precise copy milling on multiple axes.

Focus on cost-effectiveness: Long machining times and high tool wear drive up production costs. By using the right milling tools, tool life can be extended and the manufacturing process optimized for cost efficiency.

To ensure cost-effective production of forming tools, we follow a clearly structured machining sequence for prototypes: roughing with the Spinworx® D20 R3.5, semi-finishing and pre-finishing with a solid carbide high-feed milling cutter, and finally finishing with a solid carbide ball nose milling cutter.

Roughing with Spinworx® – maximum material removal rate, defined stock

First up is the Spinworx® D20 R3.5. What makes this system unique is that the inserts rotate continuously during operation, thereby utilizing their entire cutting edge evenly – without any manual interruptions. At 3,200 rpm and a feed rate of 9,600 mm/min, it removes the defined volume in less than 18 minutes (see table). What remains is a precisely defined stock. This forms the crucial foundation for reliable subsequent machining, long tool life, and a clean finishing result.

Shorter machining time for re-roughing with the solid carbide high-feed milling cutter

The D12 solid carbide high-feed milling cutter is used for roughing. Its cutting edge geometry has been optimized for high feed rates, enabling maximum material removal while maintaining stable process control. At 6,200 rpm and a feed rate of up to 15,000 mm/min, it completes the operation in nine minutes (see table) – a 27% time savings compared to conventional finishing. The remaining material is uniformly defined and provides a clean base for all subsequent steps.

Time savings in rough finishing with solid carbide high-feed cutters

Solid carbide high-feed cutters are also used for pre-finishing – this time in size D6. At 11,200 rpm and a feed rate of 15,000 mm/min, the pre-finishing time is reduced to just over five minutes, with a consistently defined allowance for the final finishing operation. Compared to conventional strategies, this corresponds to a 30% time savings—and the precise remaining material profile also protects the final finishing tool from excessive wear.

Finishing with a solid carbide ball-nose end mill – surfaces finished in a single pass

A solid carbide ball-nose end mill handles the final finishing of the complex free-form surfaces. At 22,000 rpm and a feed rate of 6,600 mm/min, it achieves the required surface finish in 50 minutes. The high speed, combined with the optimized full-radius geometry, ensures uniform surfaces that require virtually no rework.

The coordinated tool chain consisting of Spinworx®, solid carbide high-feed milling cutters, and a solid carbide ball-nose milling cutter reduces the overall lead time of the manufacturing process. Precisely defined amounts of remaining material ensure consistent cutting forces during finishing, which has a positive effect on process stability. Collisions and tool breakage are prevented – the foundation for a clean finishing result, high dimensional accuracy, and good surface quality. 

In addition, the Spinworx® system offers an economic advantage: The self-rotating inserts extend tool life and prevent machine downtime. A clear benefit in cost-effective series production.