Elliptical torus cutter tool path generation based on minimum distance computation

In mould manufacture the elliptical torus cutters are used for their high cutting velocity, but the special geometry also brings issues in tool path generating and machining quality controlling. In this paper a guide curve tool path generating method for elliptical torus cutters is presented with the cutter location points computed by a minimum distance algorithm and the path spacing determined by an adaptive method. In the minimum distance algorithm, the calculation is resolved into an iterative process from point to freeform surface and an algebraic calculation process from point to elliptical torus surface considering the geometry of the cutter, which reduces the iterative process and improves the computing speed. In the adaptive path spacing method, the contacting geometry between the elliptical cutter and the workpiece surface is analysed and the relations among the scallop height, the tool tilt angle and the path spacing are deduced, based on which the guide curves are adjusted in advance to control the scallop height. Calculating examples and experiments are carried out, showing that the consuming time of cutter location (CL) points computation algorithm is reduced by 30% comparing to earlier method, and the adaptive path spacing method performs better than constant method in both scallop height controlling and tool path shortening. The results indicate that the presented tool path generating method can help to reduce both the machining and machine waiting time as well as ensuring the machining quality.

Fabrication Methods for Microfluidic Devices: An Overview

Microfluidic devices offer the potential to automate a wide variety of chemical and biological operations that are applicable for diagnostic and therapeutic operations with higher efficiency as well as higher repeatability and reproducibility. Polymer based microfluidic devices offer particular advantages including those of cost and biocompatibility. Here, we describe direct and replication approaches for manufacturing of polymer microfluidic devices. Replications approaches require fabrication of mould or master and we describe different methods of mould manufacture, including mechanical (micro-cutting; ultrasonic machining), energy-assisted methods (electrodischarge machining, micro-electrochemical machining, laser ablation, electron beam machining, focused ion beam (FIB) machining), traditional micro-electromechanical systems (MEMS) processes, as well as mould fabrication approaches for curved surfaces. The approaches for microfluidic device fabrications are described in terms of low volume production (casting, lamination, laser ablation, 3D printing) and high-volume production (hot embossing, injection moulding, and film or sheet operations).

Project Based Learning on Casting of Aluminium Tensile Test Specimen for Mechanical Engineering Students, State Polytechnic of Malang on Odd Semester of Academic Year 2016/2017

The problem faced by students is the difficulty of understanding on metal casting topic in the lesson of Materials Technology which is conducted by lectures only. The research objective is to find out the improvement of score on metal casting topic for 1G students from Mechanical Engineering Department, State Polytechnic of Malang (Polinema) in odd Semester, Academic Year 2016/2017. Research method were facilitation of applied metal casting through pretest of metal casting, added a description of the design and modification of metal mould for Aluminium, visit to a home industry of Aluminium casting, students practice of Aluminium casting in a home industry, student groups presentation and discussion in the subtopics of (1) design and mould manufacture, (2) Aluminium casting practice, and (3) tensile testing with cast Aluminium specimen, as well as posttest on metal casting. The research result is an increasing in average score from 46.56 to 53.6 (22%) that means by adding the practice to the theory involved is increase a significant impact on understanding of Aluminium casting for students.

Effects of Vibration and Salts Treatments on Aluminium Alloy Properties Used in Mould Manufacture

Metallic mould properties are influenced by the technological process used on casting. The mechanical properties of aluminium castings can be affected by dissolved gases, heterogeneous impurities or shrinkage remaining in casting after solidification. Dissolved gases and oxide inclusions in aluminium all have a deleterious effect on casting quality. The treatment of molten aluminium using vibrations and salts was found to be highly efficient in refining the microstructure of the alloy. The main objective of the paper is to understand the effects of vibrations and salts treatment on the final microstructure and changes that take place and influences aluminium alloy properties used in mould manufacture. The microstructural changes have a great significance in improving the properties of aluminium alloy castings. Understanding this effects and the modification mechanism can undoubtedly be of great significance for improving casting quality. Fluxes based on a KCl-NaCl mixture may be used to cover and protect the metal from oxidation. Most fluxes are based on a mixture of KCl and NaCl, which forms at low-temperature (665 °C) eutectic.

Fabrication of Microfluidic Devices for Forensic Molecular Diagnostics

There have been considerable advances in the development of microfluidic devices that can carry out the automated and sophisticated processing necessary for DNA analysis and forensic biology. Polymer substrates with high replication techniques are often used in the manufacture of microfluidic devices that are single use, low cost and disposable. High replication techniques require the creation of a master mould from which the devices are subsequently fabricated. This review will describe the use of high replication techniques for device fabrication, with a focus on creation of the master mould manufacture and application of these devices in molecular diagnostics for forensic applications.

Dynamic Numerical Simulation of Mould Free-Form Curved Surface Gasbag Polishing

Polishing is an important technics processing in order to obtain the high quality surface of mould in industry mould manufacture. For the moment, polishing of the free-form curved surfaces of mould is performed by manpower. So it is important to research gasbag polishing technology. This paper has been developed dynamic numerical simulation for gasbag polishing process based on the new type of polishing tools by FEM. On the material removal theory, influence of the shape of the structure of the gasbag, angular velocity and the air pressure inside the air gasbag on the campaign polishing process are explored. It can be used to provide technology support to establish polishing process database.

On the process capability of the solid free-form fabrication: A case study of scaffold moulds for tissue engineering

This study applies the methodology and procedure of process capability to investigate a solid free-form fabrication technique as a manufacturing method to produce scaffold moulds for tissue engineering. The process capability Cp k and process performance Pp k of scaffold mould manufacture using a solid free-form fabrication technique has been analysed with respect to the dimension deviations. A solid free-form fabrication machine T66 was used to fabricate scaffold moulds in this study and is able to create features that ranged from 200 μm to 1000 μm. The analysis showed that the printing process under the normal cooling conditions of the printing chamber was in statistical control but gave low process capability indices, indicating that the process was ‘inadequate’ for production of ‘dimension-consistent’ scaffold moulds. The study demonstrates that, by lowering the temperature of the cooling conditions, the capability Cp k of the printing process can be improved (about threefold) sufficiently to ensure the consistent production of scaffold moulds with dimension characteristics within their specification limits.

Green Manufacturing of Suspended Bio-Carriers

The suspended bio-carrier is an important environment material for the biological contact oxidation of sewage treatment technology. And it is produced by mould manufacture and plastic production. In order to reduce the resource consumption and environment pollution, the green manufacturing technology is introduced; it is certified that the technology is beneficial to produce the bio-carriers. In the two stages of producing, the synthesis use of resource and the environment protection are acted as the objectives; then the multiple objective optimization models are put forward based on material selection, mould machine, and plastic injection process. The variables and constrains in those models are analyzed in detail. For models of multiple objectives, the genetic algorithm is used, and is improved by adaptively adjusting the crossover probability Pc and mutation probability Pm, and assisting gradient descending method.