#burrfree Made in Germany – Highest Quality Standards in Deburring Complex Components for Medical Technology
Precision and process reliability remain central in the German machining industry. The example of Weigel & Schwarz Präzisionstechnik GmbH in Wetzlar demonstrates how the use of specialized deburring tools from KEMPF has automated and sustainably improved the deburring of highly complex components. The focus is on a safety-relevant component used by the hydraulics specialist Roemheld in foot pumps for the medical sector.
Founded in 1957 by Richard Weigel, Weigel & Schwarz Präzisionstechnik GmbH initially specialized in linear technology. After being acquired by the Wolni family in 2004, the company gradually shifted its focus to the machining of metals and plastics. Today, managend by its second generation by Günter and Lana Wolni, the company features a modern machine park with 4- and 5-axis CNC machining centers and offers a broad range of services: from material procurement through precise machining to surface finishing and assembly. As a contract manufacturer, it primarily produces demanding, high-quality milled components in small and medium series from aluminum, stainless steel, titanium, brass, and plastics for customers across various industries, including cylinder housings, linear guides, lens and objective holders, as well as other components for the optics industry and general mechanical engineering.
Burrs Hidden Inside the Component
The Roemheld Group, headquartered in Laubach and one of the leading providers of clamping technology, assembly, and drive solutions, is also globally recognized for hydraulic components. Many inventions have emerged from the core drive to accelerate machine setup processes, including the “foot pump” in a closed design that guarantees maximum efficiency without leakage points and finds applications in automation, mechanical engineering, medical technology, and care sectors. The world market leader in this field has been working closely with Weigel & Schwarz for years on the production of certain individual components. The stringent requirements can be implemented easily and with the same quality mindset through the contract manufacturer located nearby.
A safety-relevant pump piston housing made from an AlCuMg1 aluminum alloy, initially used in lifting devices for height adjustment of assembly workstations and now in its fourth generation also employed in height adjustment of operating and instrument tables, therapy couches, and medical beds, has very specific quality demands. Due to its use in the medical field, Roemheld conducts continuous 100% inspection, as the highest standards apply to this component. For the production of this component, Weigel & Schwarz was commissioned because of their expertise and strong quality awareness. The component developed by Roemheld, featuring high mechanical fatigue strength, has a total of ten bores and an equal number of intersections, which until now had to be manually deburred in separate operations after machining at Weigel & Schwarz. Since all affected areas are inside the housing (barely visible from the outside), this was a very intensive task requiring significant labor time—an immense challenge given an order volume of approximately 15,000 components per year. To meet increasing demands and enable further development of the foot pump generations, an automated solution was necessary. Weigel & Schwarz then decided, also aiming to increase their own productivity and process reliability, to integrate deburring directly into the machining or production process. Trials followed with various tooling solutions, all of which proved unsuccessful. Manual processing remained necessary.
#burrfree Production with Just Three Deburring Solutions
It was only after contacting Marcus Schneider, field sales technician at KEMPF in Reichenbach an der Fils, that the project gained momentum again. Initially, the production of the aluminum components was viewed holistically, and taking into account the existing processes, a “deburring strategy” was developed. “When selecting the appropriate tools, it is always important to understand why and how the burrs form and where and how they are located on the component. For example, whether the burrs protrude into a main bore or are pressed from the main bore into a cross-hole,” explains Marcus Schneider. Cutting parameters and the sequence of tools used also play a crucial role in developing an implementable strategy.
The pump piston housing presented several geometry-related challenges: two deep-hole bores intersect at a defined, non-right angle with bores having a bore ratio of 1:1 on different planes. A cross-hole intersects perpendicularly with a main bore at a bore ratio of 1:2 (cross-hole to main bore) at the cutting edge near the drill tip. Another cross-hole intersects perpendicularly with a threaded bore at an approximate bore ratio of 1:2 (cross-hole to main bore). Additionally, another deep-hole bore cuts through two threaded bores outside the bore axes and “semi-openly” intersects the bottom of a cylindrical bore. The prerequisite is always that all contours and intersections must be absolutely #burrfree, as no burr may detach and enter the hydraulic system. Considering the given machining sequences and clamping situations, the deburring tools and strategies were then selected to enable a complete in-machine machining within a few weeks, ensuring that the components now come out of the machine completely #burrfree as required and expected. Markus Götzelmann, technical inside sales representative at KEMPF, selected the corresponding tools based on the drawings and 3D models. “Only three deburring solutions were necessary, which also keeps tool change times absolutely manageable,” says Lana Wolni.
Among the three selected deburring tool types is the “Back-Burr Cutter & Path deburring system”, consisting of a ball end mill (“Lollipop”) with a freedom of movement of 290° and a path (NC dataset) for contour tracing to achieve complete burr removal on the CNC machine. The optimal cutting angle is pre-calculated for each coordinate point by the NC dataset provided by KEMPF for the Back-Burr Cutter. This ensures that the cutter, as the only tooling solution currently on the market, can shift the engagement point on the cutting edge during machining, thereby utilizing the entire cutting edge rather than wearing it down at a single point. This optimization prevents premature tool wear and significantly extends the cutter’s tool life.
Two deep hole bores intersect at a defined, non-right angle with a bore having a bore ratio of 1:1 on different levels.
This intersection was deburred using the Back-Burr Cutter & Path deburring system. The cutter follows the contour precisely, guided by the NC data set provided by KEMPF, ensuring consistent, repeatable deburring results. The ball end mill, a custom design with a reduced shank and 2.3 mm diameter, is ideally suited for this type of deburring task thanks to its high-temperature-resistant AlTiCrN coating and reduced shank.
The second tooling solution used is the HSD deburring tool (High Speed Deburring). The tool is supplied with IK pressure of 6-8 bar, which actuates the cutting edges on the tool head, causing them to deploy at the desired locations in the component. The IK pressure also ensures that the cutting edges engage all recesses such as cross-holes and grooves, reliably removing the burr.
Left breakout on the bottom surface: a deep hole drill partially opens the bottom surface. This is reliably deburred with the HSD deburring tool through the deep hole drill.
The third tool type consists of two ceramic fiber brushes used to ensure complete deburring of the component. The ceramic fiber brushes, unmatched in their advantages, are made of individual ceramic fibers, which in turn consist of 80 percent technical ceramic (Al2O3 aluminum oxide) and only 20 percent binder content. This ceramic is suitable when workpieces require a special surface finish or, as in this case, when no adhesion is allowed that could potentially detach later in the oil circuit. The "oxide ceramic" also has a high hardness (harder than steel) but is simultaneously flexible enough to conform to the workpiece surface, resulting in an even grinding effect. Additionally, this type of ceramic is highly heat-resistant, dimensionally stable, and very wear-resistant during deburring and polishing operations. Another characteristic is that the individual ceramic fibers always return to their original shape after machining. For this reason, this tool type is also commonly used as a "Cross-Hole Brush" for deburring (cross-) bores. At approximately 6,000 rpm, the fibers spread out due to centrifugal force, removing even small burrs in undercuts that otherwise cannot be reached in deeper geometries.
Right breakout at the bore bottom: the deep hole drilling ends semi-open in the bottom surface, and a burr forms in the relief groove that can only be removed using the ceramic fiber Cross-Hole Brush type BÜCHA127M. At rotational speed, the individual fibers of this brush type spread out due to centrifugal force, gently removing the micro-burrs that form.
Further application in the cylindrical shoulder with relief groove: The bore exit is deburred in the first step using the HSD deburring tool with a diameter of 3.3 mm. This reliably removes the burr on all edges.
As the final tool, a second ceramic fiber brush is used at the bore exit on the cylindrical shoulder. A small residual burr that forms there after machining is completely removed with a small surface brush.
The residual burr that could potentially form in the relief groove is proactively removed laterally with a ceramic fiber surface brush of type BÜA11CB06M with a 6 mm diameter.
With this tool combination, all critical cross-holes could be deburred reliably and completely. All operations now take place directly in the machine—without additional manual rework—allowing the CNC machining center to run unattended during the second
unmanned shift
without concerns about quality.
The Result: Repeatable Quality Without Manual Rework
The results speak for themselves: Since the introduction of KEMPF tools, Weigel & Schwarz has been delivering aluminum components to ROEMHELD with consistent, absolutely burr-free quality. During 100% inspection by the quality assurance teams at Weigel & Schwarz and ROEMHELD, there has not been a single part that failed to meet the requirements. “With the block in this outstanding quality, we go directly into our assembly,” adds Alexander Schul, Product Manager at the ROEMHELD Group. For Weigel & Schwarz, this means that the components can now be produced with process reliability and high repeat accuracy. Additionally, the option for 24/7 complete machining is now available, which represents a significant economic advantage in the series production of these components and guarantees high efficiency.
From left to right: Alexander Schul, Product Manager of the ROEMHELD Group, with a ready-to-use foot pump primarily used in medical beds and therapy couches. Next to him, Lana Wolni, Managing Director of Weigel & Schwarz GmbH, with the manufactured and #burrfree pump piston housing straight out of the machine. On the far right, Marcus Schneider, Technical Field Sales Engineer at KEMPF GmbH, with the three tool types that now even enable unmanned production of the housing components.
It became clear that even established manufacturing processes hold significant potential for optimization. By integrating deburring into the CNC process, Weigel & Schwarz was able to improve quality, increase process reliability, and simultaneously use resources more efficiently within the operation. The combination of precision engineering at Weigel & Schwarz, the safety-critical requirements at Roemheld, and the tooling solutions from KEMPF highlights the importance of a process-reliable, burr-free production. This not only provides technical advantages but also reinforces the commitment to manufacturing complex and highly precise components competitively in Germany—fully in line with the “Made in Germany” standard.
Watch the video of the project here: