During the past decade, piezo-resistive cantilever type silicon microprobes for high-speed roughness measurements inside high-aspect-ratio microstructures, like injection nozzles or critical gas nozzles have been developed. This article summarizes their metrological properties for fast roughness and shape measurements including noise, damping, tip form, tip wear, and probing forces and presents the first results on the measurement of mechanical surface parameters. Due to the small mass of the cantilever microprobes, roughness measurements at very high traverse speeds up to 15 mm/s are possible. At these high scanning speeds, considerable wear of the integrated silicon tips was observed in the past. In this paper, a new tip-testing artefact with rectangular grooves of different width was used to measure this wear and to measure the tip shape, which is needed for morphological filtering of the measured profiles and, thus, for accurate form measurements. To reduce tip wear, the integrated silicon tips were replaced by low-wear spherical diamond tips of a 2 µm radius. Currently, a compact microprobe device with an integrated feed-unit is being developed for high-speed roughness measurements on manufacturing machines. First measurements on sinusoidal artefacts were carried out successfully. Moreover, the first measurements of the elastic modulus of a polymer surface applying the contact resonance measurement principle are presented, which indicates the high potential of these microprobes for simultaneous high-speed roughness and mechanical parameter measurements.

High-speed tactile roughness measurements set high demand on the trackability of the stylus probe. Because of the features of low mass, low probing force, and high signal linearity, the piezoresistive silicon microprobe is a hopeful candidate for high-speed roughness measurements. This paper investigates the trackability of these microprobes through building a theoretical dynamic model, measuring their resonant response, and performing tip-flight experiments on surfaces with sharp variations. Two microprobes are investigated and compared: one with an integrated silicon tip and one with a diamond tip glued to the end of the cantilever. The result indicates that the microprobe with the silicon tip has high trackability for measurements up to traverse speeds of 10 mm/s, while the resonant response of the microprobe with diamond tip needs to be improved for the application in high-speed topography measurements.

This research is focused on improving the efficiency of Computer Numerical Control (CNC) machining by enabling automatic feedrate selection. Model accuracy and utility are improved by a calibration process that uses spindle motor power and a wide variety of test cut geometries. A low-cost noninvasive spindle motor power sensor is combined with geometric and mechanistic models of the cutting process. Different constraints are set for rough, semi-finish and finish passes. A Numerical Control (NC) part program is processed one tool move at a time by the feedrate selection planner. For each tool move, a geometric model calculates the cut geometry. The selection algorithm then chooses the fastest possible feedrate, subject to constraints on part quality, tool health and machine tool capabilities. Experimental results for a sculptured surface bottle mould show the value of the method as an aid to process planning.

International Congress of Metrology

Multi-discipline optimization (MDO) has been proposed to handle complex optimization problems with multiple disciplines or subsystems. These problems are with global and coupling variables that are shared by more than one subsystem, which is one of the major challenges for these problems. Diverse methods that can be classified as of single- and multi-levels have been developed aiming to solve those problems. Most of these methods do not give optimization autonomies to each subsystem concerning these shared variables. This study proposed that for decomposed bi-level MDO problems, each subsystem is given full optimization autonomy in the initial stage to decide possible best solutions individually. Then all the obtained solutions are given to the system that will process the information and dispatch shared variables to each subsystem. Based on these dispatched variables, subsystems will sequentially perform the corresponding optimization with respect to their local (and global) variables with additional consistency constraints. There is no nested optimization between the system and subsystems. Six numerical and engineering examples are tested and comparisons with other methods are made to demonstrate the efficiency and applicability of the proposed approach.

Given their superior dynamics, microprobes represent promising probe candidates for high-speed roughness measurement applications. Their disadvantage, however, lies in the fact that the volume of the microprobe’s silicon tip decreases dramatically during roughness measurement, and the unstable tip geometry leads to an increase in measurement uncertainty. To investigate the factors that influence tip geometry variation during roughness measurement, a rectangular-shaped tip characterizer was employed to characterize the tip geometry, and a method for reconstructing the tip geometry from the measured profile was introduced. Experiments were conducted to explore the ways in which the tip geometry is influenced by tip wear, probing force, and the relative movement of the tip with respect to the sample. The results indicate that tip fracture and not tip wear is the main reason for tip volume loss, and that the lateral dynamic load on the tip during scanning mode is responsible for more tip fracture than are other factors.