Inline tool wear measurement in lateral micro upsetting

Abstract

Micro metal parts are usually produced in large lot sizes at high production rates. In order to achieve sufficient product quality, excessive tool wear has to be avoided. Conventional methodologies for tool wear measurement usually require tools to be disassembled and measured separately. Since accuracy of handling and assembly is limited in micro range, a reproducible tool positioning between measurements cannot be guaranteed. Therefore, analysis of tool wear development is hardly possible using conventional methods. In this study, an inline tool wear measurement methodology is investigated. Instead of measuring the tool itself, it is based on the measurement of the forming product. Therefore, lateral upsetting experiments on 1.4301 stainless steel wires with a diameter of 0.3 mm are carried out on a micro forming press. The indentation geometry on the wire is measured optically and compared to the tool geometry. It is shown that both are in good agreement for different states of tool wear and that features with geometrical characteristics above 2 μm are transferred onto the indentation surface. Thus, the investigated methodology presents a feasible way for inline tool wear measurement.

Keywords

• Micro forming
• Cold forming
• Wear