How the Back-Burr Cutter & Path Deburring System Tackles Deburring Tasks Where Other Tools Fail
The deburring system consists of a spherical deburring cutter (Back-Burr Cutter) and an NC program (Path). Both components are perfectly matched to each other, creating synergistic effects that remain unique in the market.
The deburring cutter is made of micro-grain carbide with a high-temperature-resistant AlTiCrN coating and spiral cutting edges optimized for deburring geometry. A custom NC program (Path) is created for the cutter based on the bore contour (size and shape) to be machined. Compared to other deburring tools available on the market, which often reach their limits under extreme conditions, the Back-Burr Cutter can deburr virtually any contour without generating secondary burrs, thanks to the NC program.
One Tool for Multiple Bore Diameters and Applications
Image: Overview of the different types of Back-Burr Cutters, from left to right. Type A with AlTiCrN coating and stepped shank for increased stability, available from 0.8 mm up to 9.8 mm diameter. Next, the uncoated Type A-N with extremely sharp cutting geometry, ideal for use in non-ferrous metals, plastics, and composite materials, also available from 0.8 mm to 9.8 mm diameter. Beside it, the newly developed three-flute deburring cutter for “all-round use” with even longer tool life. This cutter is also available from 0.8 mm up to 5.8 mm diameter. On the far right, the Back-Burr Cutter Type B with a solid shank for deburring tasks in hard-to-reach areas.
Components are becoming increasingly complex, making deburring operations more challenging and continuously presenting new obstacles. In the market, there are essentially only two types of tooling solutions available for CNC deburring. The majority are tools that perform linear movements while rotating. A more effective option is contour-parallel machining with the Back-Burr Cutter, which offers much greater flexibility. This is made possible by the tool path (NC data set) generated for each application and delivered together with the tool. For this reason, a single type of Back-Burr Cutter can be used for all deburring requirements, regardless of the size and shape of the contour. The deburring system is therefore capable of efficiently handling not only simple orthogonal cross-holes but also complex contours such as off-center bores, angled bores, interrupted bores, slots, thread exits, and even 3D curved contours. While conventional machining typically requires multiple tools for different bore diameters, this deburring system needs only one milling cutter variant for a wide range of diameters. To increase the versatility of the Back-Burr Cutter, the portfolio of cutters has been gradually expanded with additional variants, so that today four different “types” are offered for machining non-ferrous metals, plastics, composite materials, and even superalloys.
Best Results and Exceptional Tool Life Through Cutting Angle Optimization and Milling Cutter Replacement
Image: Essentially an impossible deburring task with conventional rotating deburring tools. Only through the combination of the deburring cutter and CNC program can such an asymmetrical contour at the uneven bore exit be deburred with process reliability. Although the aluminum cast component complicates defined deburring, the customer was impressed.
Since the movement of the milling cutter is simultaneously controlled in 3 axes, typically only a single pass (except for thread exits) is required to complete the deburring process perfectly, regardless of the material. To ensure the perfect synergy between the milling cutter and the NC program, the creation of the NC program is routinely handled by the deburring specialist KEMPF from Reichenbach-Fils. For complex applications, KEMPF even develops custom paths. These paths offer several advantages that keep the application with the Back-Burr Cutter unique. Tools that operate through linear and rotary movement always carry the risk of producing uneven edge chamfers or failing to completely remove burrs. The key factor here is the cutting edge angle, which in conventional deburring applications can only be changed minimally or not at all. The optimal cutting angle for the Back-Burr Cutter is pre-calculated for each individual coordinate point by the generated NC program, preventing the formation of secondary burrs.
Additionally, as the only tooling solution on the market, the engagement point on the cutter’s cutting edge is shifted during machining, ensuring the entire edge is utilized rather than worn at a single point. This optimization prevents premature tool wear and significantly extends the tool life of the milling cutter. In customer projects by KEMPF, tool lives of up to 50,000 bores were achieved during front and back deburring of an aluminum component with low silicon content. In C45 steel with a bore diameter of 4 mm and the Back-Burr Cutter Type A with a 3.3 mm diameter, a total of 3,600 bores were deburred burr-free on both front and back sides. The speed of the deburring process is also remarkable, resulting in substantial productivity gains almost always when replacing existing deburring tool sets with the Back-Burr Cutter. For example, the deburring operations for cross-holes on a valve shaft were reduced from three steps to a single machining operation using the Back-Burr Cutter Type A, shortening the deburring time per bore by 9 seconds. For a more complex stainless steel robotic component, the previous manual deburring was completely eliminated, reducing the total deburring time from 120 seconds to just 40 seconds.
Continuously expanding library of NC paths since market launch
Since its market launch in October 2017, the deburring system has been gaining ground steadily and has become a genuine problem solver, especially for challenging deburring tasks where other tooling systems fail. Customers frequently provide enthusiastic feedback as a result.
Image: The synergy of ball end mills type BXC-98-A with a diameter of 9.8 mm and the programmed NC data set ensures precisely reproducible deburring of the defined internal contour at the cross-hole on aluminum die-cast extruder machines for plastics processing. Thanks to the unique ability to shift the engagement point on the workpiece during machining, very long tool life can be achieved with each operation.
Steffen Hedrich, Managing Director of KEMPF GmbH, reports on an example application where genuine added value was created for the customer. “For a complex automotive component made of aluminum casting, which was to be produced in a medium-sized series of about 400,000 pieces over seven years, the required defined deburring of two internal cross-holes with an asymmetrical contour was missing for final approval,” says Steffen Hedrich. “Due to the high quantity, the deburring also had to be fully automatic directly in the machine. Despite numerous tests with various tools on the market, no other tool could meet the requirements,” he continues. The solution was the Back-Burr Cutter & Path deburring system, which exceeded all customer expectations.
Image: Detail of the bore and cross-hole contours inside the component – left before machining and right after machining with the Back-Burr Cutter & Path deburring system. The NC program enables the ball end mill to deburr this 3D contour burr-free across all components.
The desired machining operations were carried out with process reliability and consistent quality across many thousands of components, significantly improving the overall component machining time. “Although the machine time increased from 1:00 min to 1:24 min, this was more than compensated by the elimination of all manual tasks (for deburring and inspection),” adds Steffen Hedrich. Thanks to the technical deburring solution, all removable burrs could be eliminated directly in the machine without time-consuming intermediate steps, resulting in a substantial cost advantage.
Image: Close-up of the top side of the actuator housing. The magnesium cast component features numerous bores and resulting contours that require deburring. Due to this complexity, much of the deburring was initially done manually at the start of production. Only with the use of the Back-Burr Cutter & Path deburring system were the internal contours able to be machined and fully deburred using the ball end mill types BXC-33-A and BXC-48-A.
For the machining of an actuator housing (steering gear housing) made of magnesium for the automotive sector, machine deburring was even requested by the end customer. With an annual volume of 200,000 pieces, this was no easy task for the manufacturer, as the required tooling solutions simply did not (yet) exist. The main challenge was deburring an almost elliptical internal contour, which could not be accomplished with standard deburring tools. Dominik Wiesner, the responsible field service representative from deburring specialist KEMPF, r ecommended the Back-Burr Cutter & Path Deburring System , which easily mastered the previously unsolvable deburring task and achieved a tool life of approximately 20,000 parts per ball cutter on the magnesium component.
Also Used for Satellite Components
Image: Detail of the optical sensor component – clearly visible is the inner contour of the main bore deburred with the Back-Burr Cutter & Path deburring system.
An exciting challenge was deburring prototypes of highly complex optical sensor components used in satellites. Since the highest precision and manufacturing quality were prerequisites, fully automated and burr-free production was mandatory. However, for the machine deburring of the numerous bores with partially asymmetric and curved contours, the manufacturer relied on specific tooling solutions that had not been available until then. Due to the complexity of the application, KEMPF programmed a custom path specifically for this purpose and used the Back-Burr Cutter with a diameter of 3.8 mm. The slim shank provided the necessary access to trace and machine the entire contour. To achieve a perfectly burr-free result on all contours, a total of five deburring tools were used on this component, meeting the high-quality requirements without any manual rework.
Image: The path makes the difference. Unlike standard or customer-programmed NC programs , the path (NC dataset) developed by KEMPF offers many advantages that make a significant difference. Not only is the cutting angle for each individual coordinate point calculated in advance to prevent secondary burr formation, but the engagement point on the milling cutter’s cutting edge is also offset during machining so that the entire cutting edge is utilized rather than just a single point—unique in the market. This enables extremely long tool life even in difficult-to-machine materials.
As a supplier of a wide range of deburring tools, KEMPF primarily uses the Back-Burr Cutter when conventional standard tools fail to deliver satisfactory results. Beyond the mostly “simple” applications, there are always customer requests involving nearly inaccessible bore intersections or complex contours where no standard tool can be applied, or where existing tooling solutions simply do not provide a process-reliable, defined, and above all secondary burr-free result. KEMPF is happy to serve as a competent problem solver beyond the standard portfolio and can help achieve burr-free components straight out of the machine even under challenging conditions.