Professor Barthelmä, tool researchers like you have been preparing for the hybrid challenge for some time now. Which topics are currently in particular demand in classic tool technology?

Frank Barthelmä: From the point of view of tool technology, it is always exciting when users want to process different materials within a component with one and the same tool - and, of course, economically. Typical examples include composite materials such as aluminum with titanium, fiber composites in combination with metals and multilayer coating systems. There are applications in the aerospace and automotive industries and increasingly also in mechanical and plant engineering. Here, the cutting edge "encounters" different requirement profiles: I see the machining of so-called hard-soft combinations with their "zone transitions" as a challenge, for example.

What does this mean for the "tool triumvirate", i.e. the interaction of cutting material, geometry and coating?

Frank Barthelmä, GFE Managing Director: "At EMO Hannover 2019, I am particularly interested in user experiences along the entire process chain in line with the motto 'From practice - for practice'." © GFE

Frank Barthelmä: The research and development work must relate to all of these factors, including their interactions with each other. If, for example, a change has been made to the cutting material or a new cutting edge geometry has been developed, the tool developer must also adapt the coating or coating technology. However, he must also continue to pay attention to the cutting edge micro-geometry, i.e. the cutting edge shape directly in the transition area between the main and secondary cutting edge. This is particularly important for hybrid materials that are difficult to machine. The VDMA Precision Tools Association recently launched a research project in which GFE, together with partners from industry and research, is investigating such interactions in conjunction with cutting edge micro-geometries that are optimally tailored to the respective cutting process.

Increasingly, however, digitalization is also coming into play, using sensor technology and algorithms to facilitate machining in coating materials through adapted cutting processes. How do you support the tool industry and its users with current research projects?

Frank Barthelmä: There have already been some "revolutionary" developments in sensor technology, such as thin-film sensors, which are suitable for use in tools, for example. In terms of size, there has been enormous progress towards miniaturization with the same or increased performance. The ability to generate and transport data has also improved. However, it is now important to filter out exactly the right data from the sometimes enormous amount of data generated and to evaluate it in a meaningful way. However, data analysis should not only be carried out by tool specialists, but also by measurement technology and electronics experts through to IT specialists. This will generally characterize future research projects. The early involvement of the actual end users is also required.

Can experience from the EU project "Dyna-Tool - Increasing efficiency in machining", which you are working on together with international partners, also be transferred to hybrid materials?

Frank Barthelmä: Yes, because the materials in a hybrid component have different properties such as hardness or structure. The sensor technology must be able to register or analyze these properties with sufficient accuracy in order to derive useful information for the process design. This prevents a process from "building up": For example, that undesirable oscillations occur. Projects such as Dyna-Tool demonstrate how this can be prevented from the outset by intervening in the process at an early stage. Here, the focus was on how sensors in tools and tool holders can be used to stabilize machining processes despite vibrations.

However, not only workpieces, but also tools are available in hybrid layered construction, some of which are then also additively manufactured. How does 3D printing affect the behavior of these hybrid tools (elasticity, wear, vibration behavior) during machining, what does the user need to be aware of?

Frank Barthelmä: Of course, the principle here is that a hybrid or additively manufactured tool must not only have the same properties as conventional tools, but rather better ones. And this is always the case where additive processes can be used to create form elements or geometries that could not otherwise be realized. Of course, lightweight construction is also a major topic here. At the Schmalkalden Tool Conference, for example, we presented large drills in hybrid design in the GFE test field: For large-diameter boring tools, we have realized the so-called traverse in layered construction and, by cleverly arranging cavity structures inside the basic tool body, have been able to significantly reduce the mass of the overall tool while proving the same stability. A further advantage in addition to the weight saving is that the tools tend to vibrate less frequently, especially at higher speeds, and the quality of the bores is improved as a result of the smooth running.

Interested parties can find out more about these and other projects in September 2019 at EMO Hannover and the forums organized by the VDMA Precision Tools Association: What topics are you particularly interested in at Hannover - also with regard to hybrid materials?

Frank Barthelmä: I am particularly interested in user experiences according to the motto "From practice - for practice" - along the entire process chain. It would be exciting to hear about experiences that perhaps even start with the material manufacturer of "hybrid materials" and extend to the end user: I would also be interested in examples of the use of hybrid materials and components, including their effect on the energy and cost balance of the manufacturing process.

Nikolaus Fecht is a freelance journalist Gelsenkirchen