The Superman among deburring tools

How the Back-Burr Cutter & Path deburring system tackles deburring tasks where other tools give up...

When the Back-Burr Cutter & Path deburring system was introduced to the market in October 2017, even its developers had no idea what a success story it would become. The perfectly coordinated system, consisting of a deburring cutter and an NC data set generated for the application, enables high-precision CNC deburring of the most complex contours and, thanks to its innovative synergy, also promises immense tool life. Due to the new launch, a large amount of application data had to be collected at the beginning, making tool design for the respective application complicated and time-consuming. Today, the programmed paths are usually delivered directly with the tool, allowing the tool system to be installed quickly and easily in the customer's machine without the need for any programming.

The deburring system consists of a spherical back-burr cutter and an NC data set (Path). Both components are so perfectly coordinated that synergistic effects arise that are still unique on the market.
The deburring cutter consists of a micro-grain carbide with a highly heat-resistant AlTiCrN coating and spiral cutting edges with a geometry optimized for deburring. A customer-specific NC data set (Path) is created for the cutter according to the bore contour to be machined (size and shape). Unlike other deburring tools available on the market, which reach their limits, especially under extreme conditions, the back-burr cutter can deburr almost any contour thanks to the NC data set without generating secondary burrs.

One tool for multiple bore diameters and applications

Image: An overview of the different types of back-burr cutters.
From left to right: Type A with AlTiCrN coating and stepped shank for greater stability, available from 0.8 mm to 9.8 mm in diameter. Then there's the uncoated Type A-N with extremely sharp cutting geometry and therefore ideal for use in non-ferrous metals, plastics, and composite materials, also available from 0.8 mm to 9.8 mm in diameter. Next to it is the newly developed three-flute deburring cutter for "all-round use" and an even longer service life. This cutter is also available from 0.8 mm to 5.8 mm in diameter. On the far right is the Back-Burr Cutter Type B with a continuous shank for deburring tasks in hard-to-reach areas.

Components are becoming increasingly complex, making deburring increasingly difficult and constantly presenting new challenges. There are essentially only two types of tool solutions available on the market for CNC deburring. These are primarily tools that perform linear movements while rotating. A more effective option is contour-parallel machining with the back-burr cutter, which is therefore much more flexible.
Thanks to the tool path (NC data set) generated for each application and delivered with the tool, this is possible with the back-burr cutter. Therefore, one 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 machining not only simple orthogonal cross-holes but also complex contours such as off-center holes, angled holes, interrupted holes, elongated holes, threaded exits, and even 3D curved contours. While conventional machining requires multiple tools for different bore diameters, for example, this deburring system requires just one cutter variant for a wide range of diameters. To make the back-burr cutter even more versatile, the portfolio of cutters has been gradually expanded to include additional variants, so that four different "types" are now available for machining non-ferrous metals, plastics, composite materials, and even superalloys.

Image: Essentially impossible deburring with conventional rotating deburring tools. Only the interaction of a deburring cutter and CNC program allows such an asymmetrical contour at the uneven bore exit to be reliably deburred. Although the aluminum casting makes defined deburring difficult, the customer was delighted.

Since the movement of the milling cutter is controlled simultaneously in 3 axes, usually only a single pass (except for thread exits) is necessary to complete the deburring process perfectly (regardless of the material).
To guarantee the perfect synergy between milling cutter and NC data set, the creation of the NC data set is handled as standard by the deburring specialist KEMPF from Reichenbach-Fils. For complex applications, KEMPF even creates special paths. These paths have several advantages that still make the application with the Back-Burr Cutter unique. With tools that function through their linear movement and rotary movement, there is always the risk of creating uneven edge chamfers or incompletely removing burrs. The main factor here is the machining angle of the cutting edge, which can not be changed or can only be changed to a very limited extent in conventional deburring applications. With the Back-Burr Cutter, the optimal cutting angle is calculated in advance for each individual coordinate point using the created NC data set, thus preventing the formation of secondary burrs. Secondly, the unique tool solution on the market offsets the engagement point on the cutting edge of the milling cutter during machining, ensuring that the entire edge is utilized and not worn away in specific areas. This optimization prevents premature tool wear and significantly extends the service life of the milling cutter. For example, in customer projects at KEMPF, service lives of up to 50,000 holes were achieved when deburring the front and back of an aluminum component with a low silicon content. In C45 steel with a 4 mm hole diameter and the Type A Back-Burr Cutter with a 3.3 mm diameter, a total of 3,600 holes were deburred on the front and back without secondary burrs.
The speed of the deburring process is also remarkable, which almost always results in significant productivity gains when replacing the existing deburring tool and using the Back-Burr Cutter. For example, the machining steps for deburring cross holes on a valve shaft were reduced from three to a single machining step using the Back-Burr Cutter Type A, and the deburring time per hole was shortened by 9 seconds. For a more complex stainless steel robot component, the previous manual deburring work was completely eliminated, and the total deburring time was reduced from 120 seconds to just 40 seconds.

Since its market launch in October 2017, the deburring system has become increasingly popular and is a true problem solver, especially for difficult deburring tasks where other tool systems fail. Customers often provide enthusiastic feedback.

Image: The synergy of the BXC-98-A ball nose end mill with a 9.8 mm diameter and the programmed NC data set guarantees precisely reproducible deburring of the defined inner contour of the cross bore on cast aluminum extruders for plastics processing. The unique ability to offset the contact point with the workpiece during machining allows for very long tool life in every machining operation.

Steffen Hedrich, Managing Director of KEMPF GmbH, reports on an example application that generated real added value for the customer. "For a complex automotive component made of cast aluminum, which was to be produced in a medium-sized series of approximately 400,000 units over seven years, the required defined deburring of two internal cross bores with an asymmetrical contour was missing for final approval," explains Steffen Hedrich. "Due to the high volume, deburring also had to be carried out fully automatically directly in the machine. Despite numerous tests with various tools on the market, no other tool could meet the requirements," he continues. The solution to the problem was the Back-Burr Cutter & Path deburring system, which exceeded all the customer's expectations.

Image: Section of the bore and cross-bore contours inside the component – ​​on the left before machining and on the right after machining with the Back-Burr Cutter & Path deburring system. Thanks to the NC data set, the ball nose cutter can also deburr this 3D contour across all components without secondary burrs.

The desired machining operations could be performed reliably and with consistent quality across many thousands of components, and the overall component processing time was significantly improved. "Although the machining time increased from 1 minute to 1 minute, this was more than compensated for by the elimination of all manual activities (for deburring and inspection)," adds Steffen Hedrich. Thanks to the technical deburring solution, the entire removable burr could be removed without time-consuming intermediate steps in the machine, resulting in a significant cost advantage.

Image: A close-up of the top of the actuator housing. The cast magnesium component has numerous holes and the resulting contours that require deburring. Due to this complexity, much of the deburring was done manually at the beginning of production. Only with the use of the Back-Burr Cutter & Path deburring system, the internal contours could be machined and completely deburred using the BXC-33-A and BXC-48-A ball nose end mills.

For the machining of a magnesium actuator housing (steering gear housing) for the automotive sector, mechanical deburring was even requested by the end customer. With a production run of 200,000 units per year, this was no easy task for the manufacturer, as the necessary tooling solutions simply weren't available (yet). The main difficulty was deburring an almost elliptical inner contour, which was impossible to machine with commercially available deburring tools. Dominik Wiesner, the responsible field sales representative at deburring specialist KEMPF, also pointed to the deburring system, which mastered the previously seemingly intractable deburring task without any problems and achieved a service life of approximately 20,000 parts per ball milling cutter for the magnesium component.

Image: Section of the optical sensor component – ​​the inner contour of the main bore, deburred with the Back-Burr Cutter & Path deburring system, is clearly visible.

Another exciting challenge was the task of deburring prototypes for highly complex optical sensor components used in satellites. Since the highest precision and manufacturing quality are essential, completely machined and burr-free production was mandatory. However, when it came to machine deburring of the many holes, some of which had asymmetrical and curved contours, the manufacturer was dependent on suitable tool solutions that had not been available until then. Because the application was so complex, KEMPF programmed a special path and used the back-burr cutter with a diameter of 3.8 mm. The slim shaft provided the necessary access to trace and machine the entire contour. To achieve the perfect burr-free result on all contours, a total of five deburring tools were used on this component, ensuring that the high quality requirements were met without any manual post-processing.

Image: The path makes the difference. In contrast to standard or self-created NC programs, the path (NC data set) created by KEMPF offers many advantages that make a big difference. Not only is the cutting angle calculated in advance for each individual coordinate point to prevent secondary burrs, but the engagement point on the cutter's cutting edge is also shifted during machining so that the entire cutting edge is utilized and not just blocked at specific points – unique on the market. This makes immense tool life possible, even in difficult-to-machine materials.

KEMPF, a supplier of a wide range of deburring tools, primarily uses the back-burr cutter when usable results cannot be achieved with conventional standard tools. Beyond the largely "simple" applications, there are still frequent inquiries from customers who cannot rely on standard tools due to virtually inaccessible hole overlaps or complex contours, or whose existing tool solutions simply do not deliver a reliable, defined, and, above all, secondary burr-free result. KEMPF is happy to provide competent solutions even beyond its standard portfolio and can help achieve burr-free components directly from the machine, even under difficult conditions.

More information about the Back Burr Cutter & Path deburring system »