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Development of Hard Turning towards a Micron Accuracy Capability Process for Serial Production


The outcome of the project comprises the main results listed below:
-Development of a new fully hydrostatic machine tool with sub-micron accuracy for hard machining of small components,
-Development of the prototype of a high-precision, in-cycle measuring system with measuring accuracy in the sub-micron range (< 1 µm),
-Development of a prototype force measuring system which is able to monitor tool wear,
-Development of the process technology for the high precision manufacture of bearing and hydraulic components including error compensation strategies,
-Development of finite element based models describing part quality and making it possible to calculate in advance the errors which may be expected from thermal effects of the cutting process,
-Development of dedicated precision tools and tool holders.

Beyond these developments comprehensive machining tests and investigations led to a visible progress in terms of a better understanding of the hard turning technology in several fields. These investigations make it possible to use the systems mentioned above in an optimum manner.
The main working fields were:
-Investigations in machine related errors and their effect on part quality as well as the direct comparison of two different machine tool concepts,
-Investigation in the influence of clamping on part accuracy,
-Capability study and testing of the measuring system for in-cycle measurement which is integrated in a lathe and development and assessment of error correction strategies when using such a system for high precision hard turning,
-Investigations in errors caused by tooling and process by means of comprehensive machining tests, functional tests and analysis by measurement or simulation,
-Investigations in suitable grinding techniques for high-precision cutting edges and investigations in the design requirements of appropriate tool holders,
-Investigation of the use of the FEM-based models for error correction and development of strategies for the improvement of the process layout by the use of these models,
-Functional tests of the behaviour of hard turned surfaces in bearing application (lift off and live time tests) and hydraulic application (sealing tests).By the use of the systems it is possible to increase the level of manufacturing accuracy. Beyond that it is now easier to assess the potential of hard turning for high precision applications.
The levels of part quality currently consistently achieved by hard turning in industrial practice is insufficiently high for many of the fields of application. In areas such as, for example, roller bearing manufacture or the manufacture of components for fuel injection and hydraulic systems, the level of accuracy required is in the range < IT4 (ISO-tolerance class). For this reason, recourse almost always has to be made to grinding and honing processes in serial manufacture. The need to make the manufacturing process more cost effective and environmentally friendly along with the steep increase in the complexity of the components, have made it necessary to develop more flexible and environmentally friendly techniques for the manufacture of precision parts. For this purpose a reliable hard turning process with all its economic and ecological advantages, will be developed in the course of this project. The principle aim of the project is to achieve a sub-micron accuracy level for diameter tolerances of IT3. In order to fulfil this aim the following sub-systems have to be developed:
Development of two different machine tool concepts with sub-micron accuracy for hard machining of steel,
Development of high-precision, in-process monitoring with measuring accuracy in the sub-micron range (< l mm),
Development of process technology for the high precision manufacture of bearing and hydraulic components including error compensation strategies,
Development of mathematical models describing part quality and of a software tool to calculate in advance the errors which may be expected,
Development of dedicated precision tools and tool holders. The project has four principle technological objectives:
Increase in manufacturing flexibility,
Increase the achievable manufacturing quality for hard turning operations from IT6 to IT3 and surface roughness level from Rz = 4 mm down to Rz < I mm mean roughness depth,
Reduce of manufacturing cost by 40%,
Facility to manufacture more complex part geometries thus affording the opportunity for functional integration. The strategic aims of the project are:
Preservation and regaining of workplaces from Asia and the USA in the field of precision manufacturing,
Strengthening of the key industry ,,precision technology" by the increase of market shares,
Reduction of coolant emission by 100% and thus complete elimination of the environmental pollution. Eleven partners from six different countries will participate in this research project. The comprehensive approach required to solve the complex difficulties discussed above is reflected in the interdisciplinarity of the project. The consortium comprises partners from different backgrounds such as metrology, machine tools, tooling and from precision engineering. It combines the scientific competence of European research institutes with the practice-oriented, technical know how of the industry. A primary focus of attention will be to support small and medium sized enterprises, an aim reflected in the fact that 40% of this project will be undertaken by SMEs.

Funding Scheme

CSC - Cost-sharing contracts


16,Kelvinbaan 16
3439 MT Nieuwegein

Participants (10)

B.V. Gereedschapswerktuigenindustrie Hembrug
1A-1b,hendrik Figeeweg
2001 HA Haarlem
Danfoss A/S

6430 Nordborg
Diamant Gesellschaft Tesch GmbH
71636 Ludwigsburg
Steinbachstrasse 17
52074 Aachen
Lund University

221 00 Lund
Minganti SpA
5,Via Dei Giardini
40128 Bologna
Ovako Steel AB

712 80 Hällefors
2,Robert-bosch-strasse 2
70442 Stuttgart
Renishaw PLC
United Kingdom
New Mills
GL12 8JR Wotton-under-edge
Seco Tools AB

737 82 Fagersta