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We developed a new 3D-AFM technique that enables imaging of high aspect ratio trenches. By measuring both lateral and vertical forces on a cantilever tip, a subharmonic mode based on the attractive tip-sample forces becomes feasible. This enables the measurement of true 3D information of samples without causing damage. This is especially relevant for semiconductor metrology, as current solutions are lagging behind the development of (near-future) lithography capabilities. Our goal: measure metrology parameters such as critical dimension (CD), side wall angle (SWA), Line edge Roughness (LER), etc.

To accommodate such a massive satellite constellation with OCT’s, the following key drivers are identified for the space terminals: - Low Size, Weight and Power (SWaP): One of the key advantages of using optical communication wavelengths over RF wavelength is that it allows for highly compact and low power OCT’s. To fully realize this potential, all components in the laser communication terminal should be targeted for high compactness, and low power dissipation – Low Recurring cost: For large constellations of satellites are with multiple communication terminals per satellites, the recurring cost of the terminals and its components need to be low for commercial viability - Low latency, high reliability and security: To guarantee secure, and reliable communication with minimum latency, this also should account for the OCT.

Driven by technology developments triggering end user’s attention, the market for nano-and micro satellites is developing rapidly. At present there is a strong focus on 2D imaging of the Earth’s surface, with limited possibilities to obtain high resolution spectral information. More demanding applications, such as monitoring trace gases, aerosols or water quality still require advanced imaging instruments, which tend to be large, heavy and expensive. In recent years TNO has investigated and developed several innovative concepts to realize advanced spectrometers for space applications in a more compact and cost-effective manner. This offers multiple advantages: a compact instrument can be flown on a much smaller platform (nano-or microsatellite); a low-cost instrument opens up the possibility to fly multiple instruments in a satellite constellation, improving both global coverage and temporal sampling; a constellation of low-cost instruments can provide added value to the larger scientific and operational satellite missions. Application of new technologies allowed us to reduce the instrument size significantly, while keeping the performance at a sufficient level. Low-cost instruments may allow to break through the ‘cost spiral’: lower cost will allow to take more development risk and thus progress more quickly. This may lead to a much faster development cycle than customary for current Earth Observation instruments. This new development approach is demonstrated using the most advanced design of a hyperspectral imaging spectrometer (named ‘Spectrolite’) as an example. Several different novel design and manufacturing techniques were used to realize this compact and low-cost design. Laboratory tests as well as the first preliminary results of airborne measurements with the Spectrolite bread board will be presented. The design of Spectrolite offers the flexibility to tune its performance(spectralrange, spectral resolution) to a specific application. Thus, based on the same basic system design, Spectrolite offers a range of applications to different clients. To illustrate this, we present a mission concept to monitor NO2 concentrations over urban areas at high spatial resolution, based on a constellation of small satellites.

SINPLEX is a sensor suite for spacecraft navigation purposes. This paper addresses the current status of the SINPLEX prototype and the systems engineering process that has led to this status. The SINPLEX prototype is currently being integrated with the aim to demonstrate Technology Readiness Level 4, i.e. a component and/or breadboard validation in laboratory environment. The ultimate goal is to reach series production of an integrated instrument sensor suite capable of navigating a spacecraft in the solar system for exploration and science missions, and for satellite servicing and related markets. The SINPLEX project is supported by the European Community Framework Programme FP7 Space.

Hier vindt u het boek over het verspanen van moeilijk bewerkbare materialen. Het is het resultaat van het TNO kennisoverdrachtproject “Verspanen van moeilijk bewerkbare materialen” Het bevat zowel achtergrondkennis als praktisch toepasbare richtlijnen en gegevens. Het is een introductie in dit onderwerp en kan ook gebruikt worden als naslagwerk. Aan de inhoud van dit boek hebben de volgende bedrijven bijgedragen: Cimcool Industrial Products BV, CNC Consult & Automation BV, Dijk Consult, Hamel metaal, Heidenhain Nederland BV, Hembrug BV, Oerlikon Balzers Coating Benelux, Seco Tools Benelux, Techno Trade. Daarnaast is bij de totstandkoming ook gebruik gemaakt van andere bronnen. Het project is uitgevoerd door TNO in samenwerking met de Koninklijke Metaalunie, het FME-CWM, Syntens, negen verspanende bedrijven en elf toeleverende bedrijven. Dit project is gesponsord door het Syntens Applicatie Centrum Productietechnologie (ACP) en de regeling TNO MKB Kennisoverdracht van het Ministerie van Economische Zaken (EZ).

Chatter is an instability phenomenon in machining processes which limits productivity and results in inferior workpiece quality, noise and rapid tool wear. The increasing demand for productivity in the manufacturing community motivates the development of an active control strategy to shape the chatter stability boundary of manufacturing processes. In this work a control methodology for the high-speed milling process that alters the chatter stability boundary such that the number of chatter-free operating points is increased and a higher productivity can be attained. The methodology developed in this paper is based on a robust control approach using μ-synthesis. Hereto, the most important process parameters (depth of cut and spindle speed) are treated as uncertainties. Effectiveness of the methodology is demonstrated by means of illustrative examples. © 2010 AACC.

One of the applications of the micromilling technology is to machine micro features on moulds by direct machining of hardened tool steels. However at this moment, this process is not industrial applicable because of the encountered problems, such as the big tool deflection, severe tool wear, and pre-mature tool breakage. A detailed examination of current commercial micro endmills showed that the geometry of micro endmills is mainly derived from macro endmills, which has been proved to be not suitable for micro hard milling application in experiments. Based on the experimental observations, the guidelines for the design of micro endmills for the micro hard milling application were generated. These guidelines were applied in the re-design of the micro endmill with the help of analytical modeling and Finite Element Analysis. The main purposes of the new design are to increase the strength of the cutting edge corner of the micro endmill and to improve the micro tool stiffness. The preliminary experiments with the new designed endmills showed that the new geometry has improved the tool performance largely.

Surface roughness is a key parameter in evaluation of engineering surface in macro scale; in case of micromilling, it is of even greater importance because the magnitude of the roughness can be comparable with the workpiece tolerance, and will have a direct impact on the quality of the microproducts. This paper presents the preliminary results of experimental investigations on micromilling process. In this study, the influence of machining parameters on the surface roughness in micromilling was studied and compared with the observations in former researches. Besides, it was found that in microscale the roughness is largely influenced by the tool runout; runout has the effect to increase the effective feed per tooth. For conventional milling, roughness can be used for tool wear criteria; however in the experiments, no obvious relation was found between wear of micro endmills and workpiece surface roughness.

This paper discusses the influence of runout on the calculation of the coefficients of mechanistic force models in micromilling. A runout mode is used to study the change of chip thickness, tool angles, and immersion period of two cutting edges of micro endmills due to runout. A new method to find the cutting coefficients was proposed based on the observations.

This paper presents a method for real-time in-process detection and control of machine tool chatter in high-speed milling including experimental validation. The occurrence of chatter limits the efficiency and accuracy of high-speed milling operations. Usually a working point (spindle-speed and depth-of-cut) that is initially stable (chatter-free) is selected. Here an experimentally validated milling model is presented that can be used for this purpose. Due to changing process conditions (e.g. heating of the spindle or tool wear) the initially chosen stable working point may become unstable. Whereas the chatter control methods proposed in literature are essentially not applicable in real-time, the presented method allows to detect the onset of chatter and automatically adjust the spindle-speed and feed in real-time (i.e. the feed remains nonzero during the entire machining operation) to suppress the occurrence of chatter due to changing process conditions.

Proper setting of cutting conditions is critical for the performance of micro endmills in micro milling of hardened tool steels. In this paper, the influence of the cutting parameters on the wear behaviour of micro square endmills is presented. The selected parameters are cutting speed, depth of cut, and feed per tooth; Central Composite experimental Design (CCD) was used for a statistical analysis of the influence of these parameters. A quadratic model was fitted to describe the performance of the tool wear; the ANOVA analysis shows that the quadratic model gives a good prediction of the experimental results. On considering the magnitudes of the coefficients it is seen that the feed per tooth has a greater influence on the tool wear than cutting speed and depth of cut within the tested process window. By applying this method, the micromilling process can be planned to achieve an optimum tool wear performance for a tool-workpiece combination.

In experimental investigations of micro milling of hardened tool steel SAE H11, with a hardness of 56 HRC, with commercially available micro square endmills of Ø 0.5mm, it was observed that the endmills suffered from severe tool wear/failure. Because of these problems, the quality of the machined workpiece was not satisfying, in terms of burr formation and form accuracy. By analyzing the results, it is concluded that the current endmill geometries are not suitable for micromilling, which are mainly derived from macro endmills. Based on these observations, the design guidelines for micro endmills for micro hard milling application were generated. The tool geometries are improved by means of analytical and FEM analysis. Micro endmills with new designed geometries were manufactured and validated through experiments. The results showed that the new endmills had a tool life about 6 times longer than the endmills with original design; accordingly, the workpiece quality was also improved significantly.

Due to the scaling effect, micro endmills have low stiffness in nature, which will result in lose of form accuracy in workpiece and vibration of micro tools during micromilling process. Through analytical modeling, it is found that the neck geometry of the micro endmill has a big influence on the tool stiffness; therefore it is important to improve the neck shape to achieve a high stiffness. In this paper, five different types of neck geometries were studied first by mathematical models, and then tested by Finite Element Method (FEM) to see their influence on the tool performance. Based on the modeling results, the micro endmill geometry was re-designed; micro endmills with new geometries were manufactured and tested in experiments. The experimental results showed that the new neck geometry has higher stiffness compared with the neck geometry used in commercial endmills.

The efficiency of the high speed milling process is often limited by chatter. In order to predict the occurrence of chatter, accurate models are necessary. In most models regarding milling, the cutter is assumed to follow a circular tooth path. However, the real tool path is trochoidal in an ideal case, i.e. without vibrations of the tool. Therefore, models using a circular tool path lead to errors, especially when the cutting angle is close to 0 or pi radians. An updated model for the milling process is presented which features an updated model of the undeformed chip thickness and a time-periodic delay. Furthermore, the stability of the milling system, and hence the occurrence of chatter, is investigated using the traditional and the new model by means of the semi-discretization method. Especially for low immersion cuts, the stability lobes diagram (SLD) using the updated model shows significant differences compared to the SLD using the traditional model.

High-speed milling is widely used to manufacture products. Examples of application areas are the aerospace industry and mould industry. Cost-related considerations place high demands on the material removal rate and surface generation rate. However, in this respect restrictions on the process parameters, determining these two rates, are imposed by the occurrence of regenerative chatter. Chatter is an undesired instability phenomenon, which causes both reduced product surface quality and tool wear. In this paper, the milling process is modelled, based on dedicated experiments on both the material behaviour of the workpiece material and the machine dynamics. Moreover, an efficient method for determining the chatter boundaries in the model is proposed and applied to the model in order to predict chatter boundaries in the process parameters, such as the spindle speed and depth of cut, which both influence the material removal rate and surface generation rate. Finally, experiments are performed to estimate these chatter boundaries in practice.Comparison of the modelled chatter boundaries with these experimental results confirm the validity of the model and the effectiveness of the stability analysis proposed.

High-speed milling is widely used to manufacture products. Examples of application areas arethe aerospace industry and mould industry. Cost-related considerations place high demands onthe material removal rate and surface generation rate. However, in this respect restrictions onthe process parameters, determining these two rates, are imposed by the occurrence of regenerativechatter. Chatter is an undesired instability phenomenon, which causes both reduced productsurface quality and tool wear. In this paper, the milling process is modelled, based on dedicatedexperiments on both the material behaviour of the workpiece material and the machine dynamics.Moreover, an effcient method for determining the chatter boundaries in the model is proposedand applied to the model in order to predict chatter boundaries in the process parameters, suchas the spindle speed and depth of cut, which both influence the material removal rate and surfacegeneration rate. Finally, experiments are performed to estimate these chatter boundaries in practice.Comparison of the modelled chatter boundaries with these experimental results confirm thevalidity of the model and the effectiveness of the stability analysis proposed.