Aircraft, wind turbines, cars, bicycles and furniture can no longer do without them - lightweight and resilient composite materials. Today, materials such as carbon fiber, glass fiber, titanium and aluminum are combined to create high-performance materials that enable the manufacture of energy-efficient and robust products. The manufacturing industry is increasingly using PCD (polycrystalline diamond) tools to machine these materials with precision. They impress with their long service life and precise cutting. However, the manufacture of PCD tools is anything but trivial.

Vollmer has 30 years of experience in the PCD field and is an international pioneer in the development of innovative technologies for the precise sharpening of PCD-tipped tools such as milling cutters or drills. Regardless of whether the PCD is integrated using sandwich plates or sintering technology, Vollmer erosion machines can be used to precisely machine tools with different geometries. In a combined process, measuring, eroding, grinding and polishing are carried out in just one clamping operation.

The production process for PCD rotary tools

The machining of the geometry plays a central role in the tool manufacturing process. This is where the quality of the PCD rotary tool is decided. The first step in the manufacturing process is the design and layout according to the requirements that the tool has to prove in the application. Once the basic body has been manufactured, the geometry is machined using the eroding, polishing and grinding processes. This is followed by the process steps of quality, securing, balancing and labeling to finally prepare the finished product for delivery.

Different processing of cutting materials

EDM is only one possible process when it comes to machining ultra-hard cutting materials such as PCD, CBN or CVD diamond. There are also other processes such as grinding and laser machining. In EDM, a general distinction is made between two processes, such as disk and wire EDM. In disk erosion machines, the electrode consists of a rotating copper disk, whereas in wire erosion, a coiled erosion wire is used. The appropriate process is selected depending on the geometry and the cutting material to be machined: the wire, for example, for tools with internal cutting edges or complex stepped tools that have low manufacturing tolerances; the disk, on the other hand, for straight cutting edges or less complex profile tools or drilling tools. In order to be able to better compare the different stock removal processes, the possible stock removal volume and the achievable surface quality are compared in each case. Grinding processes generally ensure a finer surface, but remove less volume within the same time units.

Whether drills, milling tools or complex profile tools - Vollmer has a versatile machine portfolio for manufacturers of PCD tools. This includes wire and disk erosion machines such as the VPulse 500 and QXD 250, which are easy and simple to operate. Thanks to the Vollmer operating concept, complex machining tasks can be completed quickly, safely and reliably after just a short training period. The concise Vollmer symbols enable intuitive programming.

Wire EDM at the cutting edge

The VPulse 500 wire erosion machine is not only the successor to the proven QWD series, but is also equipped with a new erosion generator and the most advanced technology. PCD-tipped tools can be produced quickly and precisely in large quantities with this machine. Modern machine kinematics are responsible for high profile accuracy in production and maintenance. Vollmer relies on intuition for the operating concept of the VPulse 500: The touchscreen is an advanced human-machine interface that enables simple programming and control, ensuring fast and error-free operation.

The heart and pulse generator of the VPulse 500 is the Vpulse EDM generator technology. The high-performance generator ensures a higher removal rate or improved surface quality. As with the previous QWD machines, the erosion wire acts as an electrode in the VPulse 500. The wire is guided so close to the workpiece that a spark is created between the electrode and the workpiece, which removes the material at the PCD-tipped cutting edge. Thanks to the fine erosion wire, complex geometries and the smallest inner radii can be precisely machined - structures that are typical for stepped or bell tools.

Faster machining of PCD tools

With the QXD 250, different PCD tools can be sharpened precisely in a single clamping operation. In addition to the extensive software available for plate-tipped PCD tools, the ExLevel Pro software enables hybrid sharpening - eroding and grinding - of cylindrical blanks with sintered or soldered PCD to drills, milling cutters or reamers. With the HC 5 and HC 11 pallet magazines, the machine can be extended by up to 28 and 64 workpiece positions respectively. Vollmer has also worked on process optimization for the QXD 250: The company now offers a new performance package consisting of software and hardware that can significantly improve machine performance in terms of efficiency. This is achieved through the interaction of generator technology, process parameters, gap evaluation and drive technology. The performance package is one of the first products in Vollmer's new V@dison digital initiative. It is intended to provide tool manufacturers with a gradual and practical introduction to the topics of IoT (Internet of Things) and Industry 4.0.

It is to be expected that PCD-tipped rotary tools will become increasingly popular, not only as custom-made products but also across the board. Thanks to economical and precise machining processes, PCD will continue to establish itself in high-performance machining. A development for which tool manufacturers should now prepare themselves with appropriate PCD machining processes.

Dr. Stefan Brand, Managing Director of the Vollmer Group / ag