Pico- and Femtosecond Laser Micromachining for Surface Texturing

The pico- and femtosecond laser micromachining has grown up as a reliable tool for precise manufacturing and electronic industries to make fine drilling and machining into hard metals and ceramics as well as soft plastic and to form various nano- and microtextures for improvement of surface functions and properties in products. The ultrashort-pulse laser machining systems were developed to describe the fine microdrilling and microtexturing behavior for various materials. Accuracy in circularity and drilled depth were evaluated to discuss the effect of substrate materials on the laser microdrilling. Accuracy in unit geometry and alignment was also discussed for applications. A carbon base mold substrate was micromachined to transcribe its microtextures to transparent plastics and oxide glasses. Three practical examples were introduced to demonstrate the effectiveness of nano-/microtexturing on the improvement of microjoinability, the reduction in friction and wear of mechanical parts and tools, and the surface property control. The fast-rate laser machinability, the spatial resolution in laser microtexturing as well as the laser micromanufacturing capacity were discussed to aim at the future innovations in manufacturing toward the sustainable society

Development of sputtered techniques for thrust chambers

Techniques and materials were developed and evaluated for the fabrication and coating of advanced, long life, regeneratively cooled thrust chambers. Materials were analyzed as fillers for sputter application of OFHC copper as a closeout layer to channeled inner structures; of the materials evaluated, aluminum was found to provide the highest bond strength and to be the most desirable for chamber fabrication. The structures and properties were investigated of thick sputtered OFHC copper, 0.15 Zr-Cu, Al2O3,-Cu, and SiC-Cu. Layered structures of OFHC copper and 0.15 Zr-Cu were investigated as means of improving chamber inner wall fatigue life. The evaluation of sputtered Ti-5Al-2.5Sn, NASA IIb-11, aluminum and Al2O3-Al alloys as high strength chamber outer jackets was performed. Techniques for refurbishing degraded thrust chambers with OFHC copper and coating thrust chambers with protective ZrO2 and graded ZrO2-copper thermal barrier coatings were developed

Embedding of fibre optic sensors within flexible host

This work deals with the establishment of a UV polymerisation procedure combined with moulding technology towards the development of a mass production technology for the fabrication of flexible polymers with optical fibres embedded. The concept is to provide an artificial sensing skin based on fibre optic sensors which can be applied to irregular or moveable surfaces for distributed pressure applications, as for instance in structural monitoring or rehabilitation. The selected polymers for such an application are here reviewed and their composition adjusted in order to accommodate the required flexibility. As compared to other techniques, UV polymerisation advantages are pointed out when moving towards industrial applications and large scale productions. Meanwhile, curing tests to embed optical fibres in the developed polymers are carried out with an in house developed glass mould set-up and the results are presented. Laser ablation of polymers is also discussed in order to reply the demand of complex fibre layout as for example meandering or curved shape patterns

MICRO ELECTRO-DISCHARGE MACHINING: TECHNIQUES AND PROCEDURES FOR MICRO FABRICATION

Using a Panasonic MG-72 Micro Electro-Discharge Machine, techniques and procedures are developed to fabricate complex microstructures in conductive materials and engineered ceramics

A Testpart for Interdisciplinary Analyses in Micro Production Engineering

AbstractIn 2011, a round robin test was initiated within the group of CIRP Research Affiliates. The aim was to establish a platform for linking interdisciplinary research in order to share the expertise and experiences of participants all over the world. This paper introduces a testpart which has been designed to allow an analysis of different manufacturing technologies, simulation methods, machinery and metrology as well as process and production planning aspects. Current investigations are presented focusing on the machining and additive processes to produce the geometry, simulation approaches, machine analysis, and a comparison of measuring technologies. Challenges and limitations regarding the manufacturing and evaluation of the testpart features by the applied methods are discussed.Video abstrac

Influence of viscosity on grinding in ball-mills

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Plasma texturing for enhanced tribological performance of cast iron

Cathodic plasma electrolysis (CPE) was used to create surface texturing on gray iron samples, which could reduce the friction and increase the wear resistance. During the treating process, cast iron sample served as a cathode where the plasma discharging occurred, increasing the surface hardness and leaving an irregular array of micro craters on the surface. Modified surface morphology was determined from scanning electron microscope (SEM) and surface profiler. Recessed and protruded surface textures were observed when the CPE was applied at low and high voltages, respectively. Pin-on-disk tribotests were conducted on CPE-treated samples and untextured sample. The friction of as-treated samples could be reduced in boundary lubrication regime at low sliding speed due to the ability to store lubricant. Besides that, the surface texture generated extra hydrodynamic pressure that separated two sliding surfaces, increased the oil film thickness and accelerated the transition from boundary to mixed lubrication at high sliding speeds

UV-LITHOGRAPHIC PATTERNING OF MICRO-FEATURES ON A CONICAL MOLD INSERT

In past studies, several techniques have been employed to create microscopic features on relatively simple surfaces. Of these, lithography-based techniques have proven effective at manufacturing large fields of deterministic microasperities and microcavities on planar and cylindrical substrates. The present study focuses on adapting UV-lithography to a more complex substrate. Machined from stainless steel, a conical mold insert introduces an interesting geometry designed for the injection molding of radial lip seal elastomer. The distinct shape of this mold insert poises unique challenges to a conventional lithography procedure. Spray application is investigated as a feasible means to deposit layers of photoresist on the surface. An appropriate masking element is designed and created to facilitate transfer of a particular pattern via UV exposure. A clamping technique is implemented to align and secure the photomask. These techniques are incorporated into a three-day process, and results are obtained through optical microscopy and light interferometry. By applying Design of Experiments (DOE) and Analysis of Variance (ANOVA), significant process variables are indentified. Based on these findings, refinements to the process are enabled and future considerations are made evident

Material removal simulation for steel mould polishing

The surface finish of an injection mould influences the quality of the moulded polymer optic parts. In order to improve and control the surface finish of the mould it is important to be able to predict the material removal during the polishing process of this mould. The aim of this work is to predict the material removal during the polishing process, comparing the results obtained from polishing attempts on steel samples and the results obtained from a simulation model. A simulation model is developed with the abrasive wear Holm-Archard equation in ANSYS. This simulation model will help to eliminate the iterative trial and error polishing, therefore facilitating the steel mould production