Technical Work Packages

WP1: Development of prototype microprobes and optimisation of probing tips

WP1 aims to overcome the wear of the brittle silicon tips of the microprobes; thus it does so by the development of prototype microprobes and the optimisation of probing tips. 

Task 1.1 The aim is to optimise microprobe tips for fast roughness and surface property measurements on-the-machine. Two solutions for wear resistant microprobe tips will be developed: (Approach 1) diamond tips glued to tip-less microprobes and (Approach 2) hard coated microprobe tips.

Task 1.2 The aim of is to develop microprobe prototypes with wear resistant tips, with damping, with a piezo-electric actuator and preamplifier. Two prototype microprobing systems are then developed using the wear resistant microprobe tips (hard tips) from 1.1.

Task 1.3 The tip form and the wear of the new wear resistant tips from 1.2 and to develop algorithms for the morphological filtering of measured profiles of tip shape. The target is an expanded measurement uncertainty of U = 50 nm, in order to obtain comparable uncertainty levels of the measured roughness and surface parameters.

Task 1.4 The aim of this task is to improve the reliability of prototype microprobe measurements on-the-machine by measuring probing force. As part of this the maximum possible scanning speed will be calculated for different rough and hard samples in order to prevent the microprobe from flying.


WP2:  Development of new large-deflection, high-speed, low tip-wear microprobes for industrial measurement conditions

Future in-line applications with rolls of paper-making machines, micro-finished workpieces (contaminated with oil and wear particles) and randomly moving and vibrating workpieces require the development of novel probes with the following functionality. The aim of this work package is to provide improved CAN50-2-5 and newly developed tactile microprobes designed to fulfil the below specifications:

Task 2.1 Measurement range and predeflection Rolls of paper-making machines require a vertical measurement range of ± 200 µm for safe detection of all features and a predeflection to + 200 µm. Further predeflection is also needed, since the probing force of = 750 µN, which is necessary to keep the tip in contact to the sample at high scanning-speeds (15 mm/s), leads to a deflection of the microprobe.

Task 2.2 Damping During high-speed scanning of high-aspect-ratio micro features of machined workpieces the probing tip can lose contact to the surface and oscillations may appear, especially if cantilever resonance modes are excited. Damping is necessary ideally to its critical value of D = 0.5, which can be done using active damping or material damping by a layer of high-loss material on the cantilever.

Task 2.3 Self-actuating cantilever Characterisation of thin protecting rubber layers on rolls of paper-making machines by FDC and CR methods. For these methods, the probes need an integrated actuation with Dz = ± 50 nm.

Task 2.4 Contact resonance Simultaneous measurement of form and roughness and material parameters, e.g. thin deposits on a workpiece, using CR measurements. The micro probe is excited in the fundamental resonant out-of-plane bending mode and contact stiffness is recorded using a PLL circuit. To increase the sampling rate of 40 Hz obtained with CAN50-2-5 microprobes to > 1 kHz the cantilever has to be operated in a higher-order bending mode. For improved signal-to-noise ratio an integrated actuator will be necessary, which will be designed for the mode to be selectively excited.


WP3:  Development of methods for the measurement of surface properties on-the-machine

The aim of this work package is to develop two different techniques, namely FDC and CR, for the measurement of surface properties of an object on-the-machine.

Task 3.1 Will compare FDC and CR in order to determine their suitability for the measurement of surface properties of an object on-the-machine.

Task 3.2 Will develop methods, based on FDC, to detect the presence of layers of lubricants on samples and working pieces in a large thickness range (between 10 and 500 nm).

Task 3.3 Will develop methods, based on FDC and CR, to measure thickness differences of coating layers on machines and working pieces. The target thickness range is between 10 nm and 1000 nm.

Task 3.4 Will develop methods, based on FDC and on CR, to measure or characterise different material properties, such as stiffness, adhesion and friction, of workpieces on-the-machine. Such material properties can be used to highlight material contrasts on the sample surface. Furthermore, a new software tool for FDC analysis will be developed by CMI using Niget, a free software tool for the analysis of force-distance data


WP4:  Development of measung methods resistang against ambient influences

The aim of this work package is to develop methods for integrating ultrafast measuring microprobes directly onto measuring machines. Three different applications of the microprobes will be concentrated on.

Task 4.1 The first application is ultrafast roughness measurements of the workpiece or machined part on micro-finishing machines. Due to the unstable environment within micro-finishing machines, the measuring process and the microprobe have to be resistant against vibrations, temperature changes and cooling lubricant.

Task 4.2 The second application is topography measurements with microprobes on roll grinding machines. In the paper and steel industry large-scale rolls are used and the roundness of rolls is important for the quality of products. Rolls are reground at regular intervals and roundness measurements are made throughout the machining process. In recent years the surface texture of rolls has become more and more important to the industry. However, the present sensors used for roundness measurements of rolls are not able to measure surface texture.

Task 4.3 The third application is wear measurements on objects using microprobes on wear measuring machines (i.e. tribological test systems). The measurement of surface damage due to wear is normally carried out post-exposure which means that only the final surface condition can be evaluated. Therefore, techniques for real time evaluation of damage from wear will be developed. NPL will use 3 of its tribological test systems for the evaluation of wear and friction behaviour of materials in industrially relevant conditions in this task.