No Manual Deburring: #burrfree PTFE (Teflon) Components Straight Out of the Machine with Just Eight Tools
The team responsible for the new project, from left to right: CNC turning process technologist Stefan Späth, CNC milling process technologist Benjamin Weichl, KEMPF technical field service representative Dominik Wiesner, and production supervisor Johann Feth.
Machining plastics is becoming increasingly important, not only in lightweight construction. Certain plastics offer clear advantages over metals, especially when durability and corrosion resistance are required. They also do not react with water, acids, or alkalis, making these materials ideal for use in medical technology or, as in the case of ElringKlinger, for analytical instruments. The specialist in plastic machining turned to deburring specialist KEMPF from Reichenbach-Fils for additional expertise for a new project to fully automate the complete production of special screw caps.
Before: Manual PTFE Deburring
With the acquisition of a plastics processing company in 2001, ElringKlinger not only gradually developed the Heidenheim site but also expanded its own product and service portfolio in the field of plastics manufacturing and machining. Although this location currently employs 134 people and is one of the smaller sites, the importance of this division is steadily increasing. Due to specific requirements and advantages offered by this material, an increasing number of components are being produced from plastics, leading ElringKlinger Kunststofftechnik GmbH to specialize primarily in the machining of PTFE high-performance plastics (polytetrafluoroethylene). This fully fluorinated polymer, commonly known as “Teflon,” is highly chemically inert and also has a very low coefficient of friction. Another major advantage is that, due to its low surface energy, almost nothing adheres to PTFE, which is why the material is increasingly used beyond medical technology applications.
Equipped with extensive expertise in this area, ElringKlinger manufactures even the most complex components from this material for its customers and is known for their manufacturing quality. For this reason, nothing was left to chance in the past, and the final machining step of deburring was carried out manually despite the high effort involved, to meticulously meet every specification.
New Manufacturing Strategy
The headquarters of ElringKlinger Kunststofftechnik GmbH in Bietigheim-Bissingen has been using, for years, PKD tools from KEMPF due to quality requirements and recommended the Heidenheim plant to also rely on the deburring specialist from Reichenbach-Fils as part of a project optimization. For the upcoming production of screw caps, deburring was to be performed entirely by machine, as no personnel were available for manual deburring. Dominik Wiesner, KEMPF’s technical field service representative, not only proposed the appropriate tools for the deburring applications but also assembled a package of eight tools (including two deburring tools) to enable the entire production, including deburring, to be carried out by machine going forward.
Image: The PTFE component in main spindle machining on the lathe: The blanks are fed into the machine via bar feeder and machined completely #burrfree in the machine. KEMPF tools used include not only the deburring tools but also additional solid carbide and PKD form tools for internal boring, knurling milling, and thread turning.
Two Tools Replace Many Hands
Due to the complexity of the component with various contours, radii, bores, and intersections, not all tooling solutions from the standard range could be applied. To ensure the desired radius shape at the bore exits of the total 22 bores along the outer contour, a custom drill with a radius tip was quickly developed under the leadership of Technical Internal Sales, Markus Götzelmann. This drill also features an integrated step chamfer that countersinks the bore entry with a step. For the numerous turning and grooving operations, a series of uncoated and polished (thus sharper) solid carbide form tools were used. The knurling on the outside is produced with a PKD form tool from KEMPF, which is designed for higher cutting speeds compared to solid carbide tools and guarantees longer tool life. Finally, the use of two deburring tools was new, making manual deburring—no longer feasible for economic and personnel reasons on this project—obsolete. For this purpose, two types of the Back-Burr Cutter & Path deburring system were selected, which is ideally suited for use under these conditions.
Back-Burr Cutter & Path Deburring System Enables Machine Deburring of All Bores and Contours
The deburring system, consisting of a ball cutter and an NC program perfectly tailored for this application, unlike most deburring tools on the market, does not perform movement along the bore axis but uses a more effective method—contour-parallel deburring along the edge or contour to be machined. Using a custom NC program, the cutter precisely follows the contour of the component to be deburred, reliably and completely removing burrs, including on the backside of bores. Especially when cost-effective and fully automated production of components without manual rework is required, the Back-Burr Cutter & Path deburring system is an ideal solution.
In this process, the Back-Burr Cutter (the ball end mill itself) is offered in different variants for various applications, including versions suitable for use in plastics. For this purpose, the uncoated type “A-N” is used, featuring an extremely sharp cutting geometry without rounding, making it ideal for machining PTFE.
Overview of Tools
Six of the eight KEMPF tools used are shown here: 1-3 form turning and grooving tool, uncoated solid carbide, 4 uncoated Back-Burr Cutter, type BXC-28-A-N in custom length, 5 PCD form milling cutter for knurling, 6 radius form drill. The overall process achieved with these coordinated tools guarantees the desired speeds and feed rates, high stability, and manufacturing quality, combined with over 80% savings in labor requirements.
Screw Caps Without Secondary & Flash Burrs
For the screw caps to be machined, these advantages were required for the previously made bores, which extend approximately 33 mm into the workpiece and whose exits transition into a radius notch. The Back-Burr Cutter & Path deburring system was also used for the outer contour of the wall, as this area was not easily deburred due to the knurling. Since programming the NC data set, deburring this contour has proceeded without issues, and all customer specifications are met. Secondary and flash burrs are eliminated. The consistent quality has also eliminated customer complaints, which were repeatedly an issue in the past with manual deburring.
After the successful use of various tooling solutions from KEMPF, the concept of “#burrfree straight out of the machine” is being further expanded at ElringKlinger in Heidenheim, with corresponding tools also being used on other machines.