Tool Systems PCD Tool for Precise Injection

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The traditional gunsmith Carl Walther GmbH develops and produces sporting equipment that enjoys an excellent reputation worldwide. For manufacturing, Walther relies on a state-of-the-art machinery park and precision tools from Paul Horn GmbH.

Kneeling, prone, and standing: These are the shooting positions for the Olympic three-position rifle event in small-bore shooting. For precise shots, a steady hand and correct shooting technique, as well as a very accurate sporting rifle, are crucial for a successful competition.

"We have been relying on Horn's tool systems for a very long time. These include, for example, slot cutters, end mills, and PCD cutters, as well as various turning tools," says Walther process planner Ronny Buchholz. For the finishing of the system housing of the KK rifles, the Walther team uses the Horn PCD face mill DTM 1710. The system housing is the central component of the rifle. All other parts, such as the trigger unit, barrel, and shoulder stock, are mounted on it. Particular attention is paid to the surface quality. "All external surfaces of the system housing are visible surfaces. This is where the shooter loads the weapon, and all attention is focused on this component. A correspondingly good surface is our quality standard," says Buchholz.

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Reflective Surfaces

Before switching to the PCD cutter, the team used a solid carbide end mill for finishing. The surface quality was not bad, but depending on the finish desired by the customer, it always required additional rework. Horn technician Thomas Kisch suggested testing the PCD finishing cutter of type DTM 1710 for the finishing process.

"The task was to increase the efficiency of the finishing process, reduce cycle times, and improve surface quality to minimize rework," says Kisch. However, it was not just about a new tool. The production of the system housing was completely restructured. For the complete machining of the component, Walther acquired a new Grob G550. "By reorganizing the production of the system housing, we were able to optimize numerous milling processes and significantly reduce production time," says Buchholz.

The shorter production time was also achieved thanks to the Horn finishing mill. With the high achievable feed rates, the tool system enables a high level of productivity and efficiency. The precision-lasered PCD cutting inserts produce very high surface qualities in the finishing process. This is ensured by the quality of the PCD cutting edge, the PCD substrate, and the micrometer-precise adjustment of the planar runout. The milling body, made of an aluminum alloy, ensures a spindle-friendly, lightweight design. As long-term protection against the abrasive attack of chips, the milling body is specially surface-treated. To achieve high surface qualities and operate in the upper speed range, the tool must be finely balanced with the tool holder. For optimal balance quality, balancing holes are provided on the milling body. To achieve the best possible results, the entire machine environment must be considered and brought to the highest possible stability level. The structure of the machine, guides, spindles, and clamping systems for both the workpiece and the milling tool have a decisive influence on the outcome.

The Horn high-performance PCD cutting material consists of a sophisticated mixture of different sizes of diamond grains. The volume fraction of diamond increases, along with effective hardness, toughness, and cutting edge quality. Strict quality standards and their control are, of course, in place and ensure strong performance. For the DTM 1710 milling system, Horn offers the cutting cassettes in two different PCD substrates, depending on the material to be machined.

The results impressed the Walther team. With cutting speeds of v_c = 3100 meters per minute (~10,000 feet per minute)  and surface qualities of R_a = 0.4 micrometers (~0.000016 inches), the milling system operates at the required speed and achieves nearly mirror-like surfaces. The time savings after switching the finishing process amount to approximately eleven minutes. "We are very satisfied with the system's performance. This satisfies us, our quality assurance, and ultimately, of course, the shooter," says Buchholz.

Olympic Siscipline

Among small-bore shooters are hobbyists as well as Olympians. Among other disciplines, the three-position event is one of the most well-known. In this Olympic discipline, athletes shoot at a distance of 50 meters (~164 feet). A competition is conducted in the kneeling, prone, and standing positions. The shooter fires 40 shots per position. The allotted times per position range between 60 and 90 minutes. The competitor with the most points wins the competition. The caliber is 5.6 millimeters (~0.22 inches).

Switching to the finishing cutter was a complete success. Plans to convert additional finishing processes as well as new projects are underway. "Thanks to the ability to adjust the insert seats, the tools are versatile. We are already looking forward to the next projects with Horn," said Buchholz.