During the last few years, different research groups have been developing systems for the transition of abrasive water jet into ice abrasive water jet. The aim of this new technology is to make the technology cleaner from both practical and ecological points of view. Mineral abrasive is replaced with ice grains that melt away after the machining process, leaving the workpiece uncontaminated. Several different approaches to this technology were studied. Thermal aspects of integrating the ice abrasive water jet technology into commercially available machines were considered. The results and analyses of water temperature measurements on the ice abrasive water jet machine are presented in this article.

Ionic liquids’ synthesis via quaternization of imidazolium species is time and energy consuming process and is often carried out in organic solvents, which is not in accordance with the green aspects of ionic liquids. In order to reduce the preparation time and thereby energy costs, as well as harmful organic solvents consumption, more efficient and eco-friendly solvent-free methods have been the subject of a considerable recent attention. Herein we present a synthesis of 1-heptyl-2, 3- dimethylimidazolium bromide [C7mmim][Br] by various solvent-free methods: conventional water bath heating (WB), a microwave (MW)- and ultrasound (US)-assisted batch syntheses, as well as solvent-free synthesis within a continuous flow microreactor (MR). Results obtained were compared with respect to process kinetics, energy consumption and product quality in order to evaluate the most promising green processing approach.

Micromixers are essential components of microreactor technology. In this paper, a simple two-step design protocol for patterned groove micromixers based on numerical simulations is presented. In the first step, one groove of the staggered herringbone micromixer (SHM) is designed based on the average magnitude of transversal velocity nu(AVGyz) at the end of the groove. In the second step, different configurations of six grooves are investigated. A slightly better mixing is achieved compared to the established SHM and significantly fewer grooves are needed. Due to fewer grooves and rounded groove corners, the new design is easier to be produced by microengineering technologies (MET). Additionally, good mixing was also achieved with a modified slanted groove micromixer (SGM) configuration with the largest rounding radius at the edges. A SGM prototype was machined by micro EDM milling. The simulation results were experimentally verified with flow visualization and a good agreement was observed. The presented protocol vastly reduces the number of optimal patterned groove geometry configuration candidates to be evaluated; it is simple and effective for practical applications. (c) 2012 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

LEBAR A., BLATNIK O., JUNKAR M., ORBANIC H. (2012): Vibration assisted cutting of Gouda cheese. Czech J. Food Sci., 30: 1-8.The influence of vibrations on the process of cheese cutting applied in order to reduce friction and the cutting force was studied. The forces needed to cut through the cheese samples were measured against the variations of the temperature, cutting speed, and vibration frequency. The hypothesis which induced the research work was that assisting vibrations reduce the cutting forces and make the cutting easier for the user. In the experiments, Gouda cheese was used at 10 degrees C and 22 degrees C. The further, a conventional kitchen knife was used with four different cutting speeds from 12.5 mm/s to 75 mm/s and six vibration frequencies from 0 Hz to 150 Hz. The results confirmed the hypothesis presuming that up to 3.4 times lower forces are needed to cut through a cheese sample at 22 degrees C, and 1.55 times lower when cutting cheese samples at 10 degrees C. The results also confirmed the already known facts that the cutting forces increase with increasing cutting velocity, 2-4 times on average with cutting at 75 mm/s instead of 12.5 mm/s. Also, 2.5, times lower cutting forces were measured in cutting the cheese sample at 22 degrees C instead at 10 degrees C.

In this paper we present the measurement of temperature changes in the abrasive water jet (AWJ) water system using the thermocouples. Temperatures of water throughout the whole AWJ system from the water supply to the cutting head will be measured. The purpose of this research is to gather temperature data of the water system. The data will later be used to evaluate the results produced by the thermodynamic computer model of the Ice Jet (IJ) system, where the mineral abrasive of the conventional AWJ system is being replaced by the ice particles. The particles are generated inside the mixing chamber of the cutting head by partial transformation of the high speed water jet into ice particles. This is accomplished by injection of the cryogenic gas into the mixing chamber. The temperature control of the water entering the mixing chamber is therefore essential for the control of ice generation. The data will also be used to design and control the cooling system of the high pressure water which is also a part of the IJ research.

Microproduction is one of the fastest growing fields of industry with increasing demands from the market. A key factor in microproduction is micro-tooling. There are various micro-tooling techniques, such as LIGA, electroplating, etc., which are very accurate but on the other hand also very expensive and time consuming. An alternative process chain is applied consisting of producing the electrode for Die-Sinking Micro Electrical Discharge Machining (MEDM) by Water Jet (WJ) technology, which can not compete with above-mentioned technologies regarding the accuracy, but it is time efficient and cost effective. The final tool is to be used for replication processes and is produced by MEDM. The results present the process" chain in view of repeatability and limitations of producing micro-channel structures through statistical analysis. The analysis shows good repeatability of WJ machined features on the MEDM electrode which indicates the appropriateness of the chosen machining process. Due to the specific characteristics of involved technologies the smallest channel width is limited to 100 pm.

This article presents a novel monitoring method of abrasive water jet (AWJ) cutting process using the infrared thermography. Using this monitoring method it is possible to observe the cutting front in the workpiece and thus to determine the working efficiency of the material removal process. Experimental results showed that it is possible to obtain time versus temperature images which by further computer analysis give better insight in the process and the influence of process setup parameters on the process itself. Complex cybernetic structure was defined in order to achieve adaptive control of AWJ cutting.

Micro-products are small components already integrated in mass-market products in various fields. Micro-products show specificities compared to macro-products and their design process differs. Currently they are designed in a R&D framework, which implies much “build and test” iteration in order to optimize product design or production. As there is no stable knowledge corpus in micro manufacturing world, discussion with specialist is currently the only solution when designing and manufacturing the micro-component. In this paper a conceptual model of micro-process planning is proposed considering the specificities of the micro-world. The data and knowledge is presented in a uniform database. Further on, qualitative and quantitative properties and criteria for process planning are presented. Manufacturing of the micro-component is often realized through a process chain which is defined by a micro-technology expert who is familiar with all the data, knowledge, qualitative and quantitative properties and criteria of the micro-process candidates for the process chain. In the paper, a time efficient and cost effective process chain is analyzed in order to fill the required data in the process planning system. Process chain applied consists of Water Jet (WJ) technology to produce the electrode for Die-Sinking Electrical Discharge Micro Machining (EDMM). EDMM is further used as the next process in the process chain to produce the tool for replication processes. Based on the characterization of micro-features realized, the presented process chain cannot compete in the accuracy with the state of the art micro-machining processes and is limited to feature dimensions above 100 μm.

In electrical discharge machining (EDM), appropriate average current in the gap has to be selected for the given machining surface in order to obtain the highest material removal rate at low electrode wear. Thus, rough machining parameters have to be selected according to the machining surface. In the case of sculptured features, the machining surface varies with the depth of machining. Hence, the machining parameters have to be selected on-line to obtain appropriate current density in the gap. In this paper, inductive machine learning is used to derive a model based on the voltage and current in the gap. The sufficient inputs to the model are only two discharge attributes extracted from the voltage signal in the gap. The model successfully selects between two machining parameter settings that obtain different average surface current in the gap. It requires only voltage signal acquisition during the machining process and a simple algorithm that is easy to implement on industrial machines.

Micro-electrical discharge machining is an evolution of conventional EDM used for fabricating three-dimensional complex micro-components and microstructures with high precision capabilities. The material removal process has stochastic nature and is still not fully understood. This paper presents experimental results on observing the material removal rate (MRR) in dependence of alternating machining parameters and thus various discharge energies. We applied relatively low discharge energies as used in micro-EDM and relatively high as used in conventional EDM. Copper rods were used as electrodes. MRR of anode and cathode was measured. We concluded that the quotient between anode MRR and cathode MRR changes significantly when using parameters for micro-EDM in comparison to conventional EDM setup.

In order to improve the accuracy of abrasive water jet (AWJ) machining the precise value of the jet diameter has to be known. Because of an aggressive environment caused by high velocity abrasive grains, the diameter is not easily measured. That is why a measuring device consisting of a load cell and a wear resistant probe was developed. The device measures the force of the jet while it passes over the edge of the probe. If the feed rate of the jet is constant and the time needed for jet to pass is known, the diameter can be determined. Because of probe wear issue several preliminary tests were made with water jet only in order to determine the measuring uncertainty and accuracy of the device. In the end the measurement of the AWJ was performed for two different focusing nozzles of different diameters.

Incremental sheet metal forming is becoming an attractive technology for fast prototyping and small batch production of sheet metal parts. The majority of investigations are focused on the use of a rigid tool to incrementally form the sheet metal into a final shape. An interesting alternative is to substitute the rigid tool with a high velocity water jet (WJ). The comparison between using a rigid tool and a WJ shows that each method has its advantages and disadvantages. This investigation is aimed to identify the most influential parameters affecting the forming process through experimental comparison of the two observed methods. Technological windows based on non-dimensional values and relevant process parameters like force on the rigid tool and water pressure were defined.

In this paper the macro-mechanism of abrasive water jet (AWJ) cutting is studied from the point of cutting front and striation formation analysis. The striation on the surface cut with AWJ is a characteristic phenomena which is strongly present when cutting with high traverse velocities for particular material type and thickness of workpiece. The connection between the cutting front step formation and striation formation is explained through series of experiments, which include visual observations of cutting transparent material and through analogies, which deal with river meandering and wear of pneumatic conveyor bends.

This contribution presents the introduction of laminated supporting tools in water jet incremental sheet metal forming (WJISMF) process. In WJISMF the main tool is a high-velocity water jet (WJ) instead of a rigid tool. The influence of the main tool trajectory on the forming outcome in WJISMF is observed and optimized in order to reduce the forming time and improve the product quality. Laminated tools are fabricated with abrasive water jet (AWJ) machining from aluminium plates of different thicknesses. The parts formed in this investigation are measured with a coordinate measuring machine (CMM) and results are compared by means of forming time, parts symmetry and achieved geometry, which is defined with the supporting tool.

A novel approach to avoid the knowledge gap between design and production is presented in this paper. The main idea is to build a system in the form of a computer program whose core is the manufacturing expert systems to be used by the product designer. The system reveals critical features of the designed product from the manufacturing point of view and points them out to the product designer. The product designer can decide whether to change the critical part of the product or not. The system presented in this paper is prepared for the toolmaking, where a lot of relatively cheap products are made by one relatively expensive tool. Since the shape of the cavity in the tool is the negative shape of the product, small changes in the product design can significantly reduce the manufacturing costs of the tool.

To achieve high removal rate and low electrode wear when roughing by the sinking electrical discharge machining process (EDM), appropriate average surface power density is required in the gap between the workpiece and the electrode. Since machining surface varies with the depth of machining, the rough machining parameters have to be selected on-line to obtain appropriate average surface power density in the gap. In this paper, a system for on-line selection of the machining parameters according to the given machining surface is presented. The selection of the machining parameters is based on the acquisition of only one process attribute, i.e. the percentage of short-circuit discharges, which is significant improvement comparing to known systems.