Generation of Micro Mechanical Devices Using Stereo Lithography

A high resolution machining setup for creating three-dimensional precision components from a UV-curable photo-resin has been developed. By using frequency-converted diode-pumped solid state lasers, functional micro-mechanical devices are directly fabricated in a successive layer-bylayer fashion. Within this paper, the direct generation of micro assemblies having moving components without further assembly of parts will be presented. The micro system design is based on user-defined 3D-CAD data and will completively be built up within the fabrication cycle. By using specially developed μSL materials with suitable properties for micromechanical parts, the development from Rapid Prototyping towards Rapid Production of small series is intended.Mechanical Engineerin

CAD/CAM integration based on machining features for prismatic parts

The development of CAD and CAM technology has significantly increased efficiency in each individual area. The independent development, however, greatly restrained the improvement of overall efficiency from design to manufacturing. The simple integration between CAD and CAM systems has been achieved. Current integrated CAD/CAM systems can share the same geometry model of a product in a neutral or proprietary format. However, the process plan information of the product from CAPP systems cannot serve as a starting point for CAM systems to generate tool paths and NC programs. The user still needs to manually create the machining operations and define geometry, cutting tool, and various parameters for each operation. Features play an important role in the recent research on CAD/CAM integration. This thesis investigated the integration of CAD/CAM systems based on machining features. The focus of the research is to connect CAPP systems and CAM systems by machining features, to reduce the unnecessary user interface and to automate the process of tool path preparation. Machining features are utilized to define machining geometries and eliminate the necessity of user interventions in UG. A prototype is developed to demonstrate the CAD/CAM integration based on machining features for prismatic parts. The prototype integration layer is implemented in conjunction with an existing CAPP system, FBMach, and a commercial CAD/CAM system, Unigraphics. Not only geometry information of the product but also the process plan information and machining feature information are directly available to the CAM system and tool paths can be automatically generated from solid models and process plans

A CAD/CAM concept for High Speed Cutting compatible rough machining in die, mould and pattern manufacturing

Die, mould and pattern manufacturing plays a central role in the production of capital and consumer goods. Ever-shorter product life cycles and the expanding diversity of features require continued cuts in production lead times. Recently, these developments in the market, accompanied by a simultaneous demand for improved quality at a lower cost, are becoming clearly noticeable. Along with the streamlining of organizational structures and advanced technological developments, it is above all the introduction of CAD/CAM software that offers great potential for reducing lead times for components with free surfaces. The role of milling in the integrated process chain of die, mould and pattern manufacturing is steadily gaining importance. This is due to the ongoing further development of milling-machine technology, the cutting tools and their coatings, and of the CAD /CAM systems themselves. Generally speaking, the milling process is divided into the operations of roughing and finishing. For rough milling, efficient machining means high stock-removal rates together with close contour approximation and low tool wear. Rough milling is normally carried out layer by layer, i.e. in a 2.SD machining operation with constant depth per cut because the rate of material removal and process reliability are usually highest when this method is used. High-speed cutting (HSC), which has been the subject of extensive university research for far more than ten years, has meanwhile become established as a finishing process in many companies. However, the application of HSC demands the observance of geometric and, above all, technological constraints. A considerable degree of optimization can be achieved when these constraints are applied to rough milling. In the integrated process chain, the CAD/CAM system performs the task of calculating NC programs based on CAD data which meet the requirements posed by rough and finish machining operations. While general interest was focused on the development of CAM strategies for HSC finish machining, advanced development of technology-oriented CAM modules for upstream roughing operations was neglected. The paper at hand deals with the development of a CAM module for rough-machining complex components in die, mould and pattern manufacturing. It provides an insight into the process-technological demands made on HSC operations and their application in rough machining, from which guidelines and requirements on technologically oriented NC functions for CAM software were derived. These encompass both the complete development of an interactive, dialogue-based user guidance function and the algorithmic conversion of the calculation routines. The concept at hand was almost entirely implemented and integrated in the CAD/CAM system developed by Tebis AG, Germany, which was conceived especially for die, mould and pattern manufacturing and is scheduled for introduction to the free market starting in April 2001

Latest Developments in Industrial Hybrid Machine Tools that Combine Additive and Subtractive Operations

Hybrid machine tools combining additive and subtractive processes have arisen as a solution to increasing manufacture requirements, boosting the potentials of both technologies, while compensating and minimizing their limitations. Nevertheless, the idea of hybrid machines is relatively new and there is a notable lack of knowledge about the implications arisen from their in-practice use. Therefore, the main goal of the present paper is to fill the existing gap, giving an insight into the current advancements and pending tasks of hybrid machines both from an academic and industrial perspective. To that end, the technical-economical potentials and challenges emerging from their use are identified and critically discussed. In addition, the current situation and future perspectives of hybrid machines from the point of view of process planning, monitoring, and inspection are analyzed. On the one hand, it is found that hybrid machines enable a more efficient use of the resources available, as well as the production of previously unattainable complex parts. On the other hand, it is concluded that there are still some technological challenges derived from the interaction of additive and subtractive processes to be overcome (e.g., process planning, decision planning, use of cutting fluids, and need for a post-processing) before a full implantation of hybrid machines is fulfilledSpecial thanks are addressed to the Industry and Competitiveness Spanish Ministry for the support on the DPI2016-79889-R INTEGRADDI project and to the PARADDISE project H2020-IND-CE-2016-17/H2020-FOF-2016 of the European Union's Horizon 2020 research and innovation program

Techno-Economic Analysis of Hybrid Layered Manufacturing

Subtractive manufacturing (CNC machining) has high quality of geometric and material properties but is slow, costly and infeasible in some cases; additive manufacturing (RP) is just the opposite. Total automation and hence speed is achieved in RP by compromising on quality. Hybrid Layered Manufacturing (HLM) developed at IIT Bombay combines the best features of both these approaches. It uses arc welding for building near-net shapes which are finish machined to final dimensions. High speed of HLM surpasses all other processes for tool making by eliminating NC programming and rough machining. The techno-economic viability of HLM process has been proved through a real life case study. Time and cost of tool making using HLM promises to be substantially lower than that of CNC machining and other RP methods. Interestingly, the material cost in HLM was also found to be lower. HLM is a cheaper retrofitment to any 3 or 5 axis CNC milling machine or machining center.Mechanical Engineerin

Optimization of roughing operations in cnc machining for rapid manufacturing processes

This paper presents a method for optimizing roughing operations in CNC machining particularly for parts production through a subtractive rapid manufacturing process. The roughing operation in machining is primarily used to remove the bulk of the material and to approximately shape the workpiece towards the finish form. The manufacturing process described utilizes a 3-axis CNC machine with an indexable 4th axis device that is used to hold and rotate the workpiece. The method used is derived from the multiple approaches in roughing operations that differ in the number and the angle of the orientations. Most of the machining parameters are generalized throughout the process to allow some automation in generating the machining program. Overall, the performance of each of the approaches is evaluated based on the lowest machining time to produce the part

Design of an electrochemical micromachining machine

Electrochemical micromachining (μECM) is a non-conventional machining process based on the phenomenon of electrolysis. μECM became an attractive area of research due to the fact that this process does not create any defective layer after machining and that there is a growing demand for better surface integrity on different micro applications including microfluidics systems, stress-free drilled holes in automotive and aerospace manufacturing with complex shapes, etc. This work presents the design of a next generation μECM machine for the automotive, aerospace, medical and metrology sectors. It has three axes of motion (X, Y, Z) and a spindle allowing the tool-electrode to rotate during machining. The linear slides for each axis use air bearings with linear DC brushless motors and 2-nm resolution encoders for ultra precise motion. The control system is based on the Power PMAC motion controller from Delta Tau. The electrolyte tank is located at the rear of the machine and allows the electrolyte to be changed quickly. This machine features two process control algorithms: fuzzy logic control and adaptive feed rate. A self-developed pulse generator has been mounted and interfaced with the machine and a wire ECM grinding device has been added. The pulse generator has the possibility to reverse the pulse polarity for on-line tool fabrication.The research reported in this paper is supported by the European Commission within the project “Minimizing Defects in Micro-Manufacturing Applications (MIDEMMA)” (FP7-2011-NMPICT- FoF-285614)

Design of a pulse power supply unit for micro-ECM

Electrochemical micro-machining (μECM) requires a particular pulse power supply unit (PSU) to be developed in order to achieve desired machining performance. This paper summarises the development of a pulse PSU meeting the requirements of μECM. The pulse power supply provides tens of nanosecond pulse duration, positive and negative bias voltages and a polarity switching functionality. It fulfils the needs for tool preparation with reversed pulsed ECM on the machine. Moreover, the PSU is equipped with an ultrafast overcurrent protection which prevents the tool electrode from being damaged in case of short circuits. The developed pulse PSU was used to fabricate micro-tools out of 170 μm WC-Co alloy shafts via micro-electrochemical turning and drill deep holes via μECM in a disk made of 18NiCr6. The electrolyte used for both processes was a mixture of sulphuric acid and NaNO3 aqueous solutions.The research reported in this paper is supported by the European Commission within the project “Minimizing Defects in Micro-Manufacturing Applications (MIDEMMA)” (FP7-2011-NMP-ICT-FoF-285614

A Review of Layer Based Manufacturing Processes for Metals

The metal layered manufacturing processes have provided industries with a fast method to build functional parts directly from CAD models. This paper compares current metal layered manufacturing technologies from including powder based metal deposition, selective laser sinstering (SLS), wire feed deposition etc. The characteristics of each process, including its industrial applications, advantages/disadvantages, costs etc are discussed. In addition, the comparison between each process in terms of build rate, suitable metal etc. is presented in this paper.Mechanical Engineerin

Analysis of Secondary Adhesion Wear Mechanism on Hard Machining of Titanium Aerospace Alloy

Titanium alloys are widely used in important manufacturing sectors such as the aerospace industry, internal components of motor or biomechanical components, for the development of functional prostheses. The relationship between mechanical properties and weight and its excellent biocompatibility have positioned this material among the most demanded for specific applications. However, it is necessary to consider the low machinability as a disadvantage in the titanium alloys features. This fact is especially due to the low thermal conductivity, producing significant increases in the temperature of the contact area during the machining process. In this aspect, one of the main objectives of strategic industries is focused on the improvement of the efficiency and the increase of the service life of the elements involved in the machining of this alloy. With the aim to understand the most relevant effects in the machinability of the Ti6Al4V alloy, an analysis is required of different variables of the machining process like tool wear evolution, based on secondary adhesion mechanisms, and the relation between surface roughness of the work-pieces with the cutting parameters. In this research work, a study on the machinability of Ti6Al4V titanium alloy has been performed. For that purpose, in a horizontal turning process, the influence of cutting tool wear effects has been evaluated on the surface finish of the machined element. As a result, parametric behavior models for average roughness (Ra) have been determined as a function of the machining parameters used