Innovative Deburring Solutions for Highly Complex Space Technology
With over 15 years of experience in prototype manufacturing, Seiffer & Steiner Präzisionsteile GmbH in Lauffen am Neckar has established a reputation beyond German borders. For renowned customers in the automotive industry, aerospace, as well as medical and mechanical engineering sectors, the existing expertise is applied to develop the required components, often already during the planning phase in collaboration with the customer, and to prepare them through various evolutionary stages for series production. However, for highly specialized applications in niche areas, larger series are often not achieved, so production is limited to small series or just a few parts.
Especially for these cases, the highest quality requirements are often placed on the component, particularly when they are later used in aerospace. Not only have special strips been developed for a major European aircraft manufacturer, but currently also highly complex optical sensor components intended for use in satellites. Since the highest precision and manufacturing quality are prerequisites here, fully machine-based and burr-free production was mandatory. However, especially for the machine deburring of numerous bores with partially asymmetrical and curved contours, as well as surface machining, Seiffer & Steiner relied on appropriate tooling solutions that had not been available until then. A trade show visit to the Deburring Expo in Karlsruhe and the resulting initial contact with KEMPF was set to change this sustainably.
Only Through the Use of Ceramic Tools and the Back-Burr Cutter & Path Deburring System to Achieve the Desired Result
After inspecting the component and production processes on-site, KEMPF field service technician Dominik Messaros was able to develop an expert assessment and select the necessary deburring solutions. The extensive portfolio of deburring tools in both standard and custom categories, combined with nearly 60 years of experience in burr-free machining, provides the foundation to quickly implement suitable yet cost-effective solutions even for such complex applications. To reliably and absolutely burr-free machine the many surfaces, bores, and 3-D contours directly on the machine, a variety of ceramic (fiber) tools with outstanding abrasive properties were used. For example, all cross-holes were deburred with a ceramic Cross-Hole Brush with a 7 mm diameter. This specially designed brush uses the centrifugal force to press the flanks of the ceramic fibers against the bore wall, efficiently removing fine burrs, such as those found on cross-holes. For the surface of the mounting flange on the approximately 100 mm long component made of high-strength titanium, another ceramic fiber brush was used. The surface brush with a 15 mm diameter is ideally suited for deburring flat surfaces without creating excessive edge rounding. The individual fiber rods of the brushes consist of about 1,000 bound fibers each, which are approximately 80% ceramic, allowing the cutting edges to self-sharpen during the machining process. This ensures consistent grinding performance and uniform material removal on the component. The result is excellent polishing and grinding characteristics, which contribute to outstanding surface finishes (Ra + Rz values), especially on face-milled surfaces. Various ceramic grinding pins with flexible shanks and special ceramic fiber material heads provide the necessary finishing touches, precisely performing the final fine deburring on contours and bores under 10 mm in diameter.
For the most challenging deburring tasks on the optical sensor component, the Back-Burr Cutter & Path deburring system is employed. Only through this synergistic system, consisting of a spiralized, high-temperature-resistant ball cutter and a specially generated NC data set for the application, can bore intersections, thread exits, and even the most complex contours be precisely and reproducibly deburred over extended machining times. Unlike commonly used deburring tools that perform linear movements relative to the cross-hole while rotating, this deburring system uses a more effective method—contour-parallel deburring along the edge or contour to be machined. By individually creating the data set, the cutter precisely follows the contour of the component to be deburred, safely and completely removing burrs, including on the backside of bores. Especially when cost-efficient and fully automated production of components without manual rework is required, the Back-Burr Cutter & Path deburring system is the preferred choice.
Long Tool Life – Even with Titanium
A novelty and unique feature of the Back-Burr Cutter & Path deburring system lies in the NC data set, which by default shifts the cutter’s cutting point relative to the component during machining, preventing localized wear and achieving a significant increase in tool life. Additionally, the AlTiCrN coating ensures that the cutter maintains consistent performance over an extended period, even when machining titanium. These are crucial prerequisites for use on this satellite component. Due to the complexity of the internal bore contour of the main bore, a special path was programmed, and a 3.8 mm diameter ball end mill was used. The slender shank provides the necessary access to machine the entire contour without contacting the outer surface. To achieve the perfect burr-free result, a total of five deburring tools were employed on this component, meeting the high-quality requirements without any manual rework.
PCD Milling Cutters from KEMPF Deliver the Decisive Advantage
Following these highly satisfactory results, these tools were consequently applied to a camera mount for the optics industry facing similar challenges. The large, semicircular component made of aluminum sand casting, approximately 60 cm in diameter, requires several recesses and pockets for camera mounting. The outer contour of the milled pocket, typical of casting contours and undefined, needed to be completely deburred. However, achieving process-reliable deburring was not possible due to the burrs formed during the creation of the recesses. To significantly optimize the entire process, the previously used solid carbide milling cutters, which produced excessively large burr roots, were replaced by PCD milling cutters from KEMPF. The standard KF 910 cutters with diameters of 14 mm and 20 mm, as well as a PCD custom tool with a 38 mm diameter, performed such effective pre-machining that the ceramic fiber surface brush used for deburring the contours had to remove only minimal burrs. This not only reduced wear and thus extended the tool life of the ceramic fiber brush but also the durability of the PCD cutters exceeded that of the previously used solid carbide cutters by a multiple. Since then, the camera mounts produced in medium-sized series have been manufactured using the optimized process. Manual rework is no longer necessary, as all processes are executed by machine with consistent quality.
Image: At the end section of the optical sensor component, the inner contour of the left cross-hole was deburred using the Back-Burr Cutter & Path deburring system. Additionally, the ceramic fiber surface brush BÜA32-CB15M was used on the face to deburr all contours without creating a chamfer. The cross-holes were finely deburred with a flexible grinding pin type BÜCH-PB-4B (blue) with a diameter of 4 mm.
Image: Section of the optical sensor component
Clearly visible is the inner contour of the main bore deburred with the Back-Burr Cutter & Path deburring system, as well as the surface of the mounting flange machined with the most abrasive type of ceramic fiber brush (blue brush) BÜA32-CB15M. The bore exits of the small cross-holes were reliably deburred using a Cross-Hole Brush BÜCH-A33-7M (blue) with a diameter of 7 mm.
Image: Used Deburring Tools
On the left, the installed ball end mill "Back-Burr Cutter" of type BXC-38-B with a diameter of 3.8 mm. Next to it on the right is the KEMPF KF910 PCD standard milling cutter, which, due to its cutting geometry, already enables burr-minimal milling of non-ferrous metals and plastics. In addition, significantly higher cutting parameters with longer tool life are possible compared to solid carbide tools. The blue Cross-Hole ceramic fiber brush of type BÜCH-A33-7M with a diameter of 7 mm is particularly suitable for process-reliable deburring of cross-holes. The blue ceramic fibers are the most abrasive and provide the highest grinding performance. On the right is the ceramic fiber brush of type BÜA11-CB25M. This brush with red ceramic fibers offers higher elasticity and flexibility and is ideal for fine deburring as well as polishing surfaces.
Image: The Milled Pocket
The milled side on the outside of the camera mount above the recess for the camera – to deburr the contour, the entire surface is simply traversed with a medium-abrasive surface brush (red) of the BÜA11-CB25M type. By using the KEMPF PKD standard milling cutter KF910, a burr-minimized milling process was also implemented, significantly increasing the tool life of both the milling cutter and the 25 mm diameter surface ceramic brush.