Users and applications should drive tool engineering
The tool geometry selected exerts a decisive influence on tool life and on the properties of machined parts. Coordinating the rake and clearance angles or the cutting-edge chamfer with a milling tool, for example, can achieve a significant improvement in operational characteristics. However, it is vital to harmonise the tool’s macro- and microgeometry with the requirements of the pertinent machining task, since this is the only way to ensure reliable improvement in process performance. In order to draw qualified conclusions in this context, the Fraunhofer IPT is researching selection of optimal tool geometries for diverse machining tasks within the EU-funded QuickPro collaborative project.
Qualifying optimum conditions of cutting-tool application is pivotal particularly in regard to the tool’s substrate material and coatings. It is vital to ensure that the tool and its coating are tailored to each other when difficult-to-cut materials are being machined. This enables tool life to be prolonged and the machine tool to be used in applications with higher process parameters.
In industrial practice, however, users often encounter nonuniform or nontransparent coatings that fail to fulfil their potential for efficiency. Commonly, incorrect coating application is at fault. This can result in performance fluctuations that are difficult to explain. When coating properties are not tailored precisely to the application requirements, there is no reliable improvement in tool performance.
Several important questions then confront the user: What are the advantages of tool coating? Which coating is best suited, economically and technologically, to this application? How should the machining process be designed in order to exploit the coating’s full benefits? (Through the Fraunhofer Project Centre for Coatings in Manufacturing, the Fraunhofer IPT is researching the answers to these questions collaboratively with coating experts from the Centre for Research and Technology Hellas in Thessaloniki, Greece.)
Almost all of the surveyed companies regard new cooling-lubricant strategies as important for driving improvement in machining processes. This is because lubricant strategies achieve their full process-efficiency potential only when they are fine-tuned to meet perfectly the requirements of the cutting tools being used. The principle applies to dry machining, minimum-quantity lubrication (MQL), flood, and high-pressure cooling strategies, as well as to cryogenic cooling. (Survey respondents ranked these as the most important cooling strategies.) Each approach has specific advantages and disadvantages, which must be weighed carefully when selecting the appropriate strategy for the operation at hand, in order to optimise process performance and production costs.