The International Journal of Advanced Manufacturing Technology

Thin film transistor and liquid crystal display (TFT-LCD) fabrication manufacturing is characterised as a re-entrant process, in which a similar sequence of steps is repeated several times. Production control for the re-entrant process is complex, since, without intelligent control, it may incur the congestion of WIP or equipment idleness because of the work in progress (WIP) shortage. In this paper, three kinds of control policies are suggested: push, push-pull and pull types. Exact formulations using linear programming are given, and their performances of solutions are evaluated. It is shown that a pull type control policy gives stable throughput and delivery satisfaction at a small cost and with less production. A push type policy outperforms the other two types in the throughput and manufacturing cycle time.

The definition of machining processes with respect to complex kinematic machine tool behaviour involves the control of machine accuracy and kinematic performances. The aim is to propose process settings and tool paths which guarantee the required machining quality while maximizing productivity. This article presents an experimental protocol which enables the determination of machine tool structure behaviours which have an influence on machining quality. In parallel, an experimental analysis of the different kinds of settings which can improve machining quality is carried out. Two kinds of settings appear: the first class of settings improves machining quality or machining time, and the second class has an antagonistic influence on machining quality and machining time. Thus, the definition of the second class of settings arises from an optimisation between first-order defects, second-order defects and machining time. The developed method is illustrated on a parallel kinematic machine tool, the Tripteor X7. Note that this study is a first step towards controlling machine tool behaviour during machining.

This experimental research use the method of abrasive flow machining (AFM) to evaluate the characteristics of various levels of roughness and finishing of the complex shaped micro slits fabricated by wire electrical discharge machining (Wire-EDM). An investigative methodology based on the Taguchi experimental method for the micro slits of biomedicine was developed to determine the parameters of AFM, including abrasive particle size, concentration, extrusion pressure and machining time. The parameters that influenced the machining quality of the micro slits were also analyzed. Furthermore, in the shape precision of the micro slit fabricated by wire-EDM and subsequently fine-finished by AFM was also elucidated using a scanning electron microscope (SEM). The significant machining parameters and the optimal combinations of the machining parameters were identified by ANOVA (analysis of variation) and the S/N (-to-noise) ratio response graph. ANOVA was proposed to obtain the surface finishing and the shape precision in this study.

Recycling of clothes is a straightforward approach for the supply of a coloured raw material which does not involve the cost of the colouring process. A real time and completely automated colour classification tool for woollen clothes to be recycled is proposed. The tool uses the combination of a statistical method, called matrix approach, of a self-organizing feature map (SOFM) and a feed-forward backpropagation artificial neural network (FFBP ANN)-based approach, to correctly classify the clothes by respecting the selection criteria provided by human know-how. The developed tool, which uses an appositely developed workbench with a spectrophotometer, is aware of the way the different coloured clothes to be recycled combine each other to create a new one. The tool has been validated using a set of 5,000 differently coloured clothes to be recycled and the classification error in classifying the clothes is within 5%, i.e., lower than the one resulting from the use of an expert human operator.

This paper presents a new process to produce wax patterns using a rapid prototyping made mold and a phase changing material (PCM). A numerical simulation of the system was performed to fully understand the melting and heat absorption behavior of PCM and injected wax. To do so, the specific heat of PCM and wax was modified to account for the increased amount of energy in the form of latent heat of fusion over its melting temperature range. Then, a carefully prepared experiment successfully confirmed the validity of the work. Comparable to traditional wax pattern process, this new method opens a new window to obtain wax patterns with less time and more geometry complexities while providing good accuracy. Moreover, optimization by practicing different thermal conductivity of metallic–powder–PCM mixture revealed a possibility of further shortening wax solidification time, making this process competitive with the traditional process.

In aerospace manufacturing, drilling carbon reinforced composites is one of the dominant processes. The exit-ply delamination, directly related to the drilling thrust force, occurs more often despite all precautions. In this paper, a new analytical model is presented to predict the critical thrust force at which delamination will start. The model takes into account the thermo-mechanical loads and considers a mixed mode of fracture occurring in the delamination area. This model explains how the delamination area starts with a circular cross-sectional area in the entrance layer and grows into an ellipsoid, in the same direction of the fibers, in the exit layer. Besides, the distribution of the load in the delamination area includes a center point load for the chisel edge of the drill bit and a linearly distributed load for the cutting lips. The results of the proposed model are compared with previous analytical models using three different sets of experimental data and the comparison showed that the presented model is more accurate.

Ultrasonic elliptical vibration-assisted milling methods have recently attracted attention since they can be applied to difficult-to-cut materials. In this study, the effects of rotary ultrasonic elliptical machining parameters for side milling on Ti-6Al-4V titanium alloy machined surface integrity were investigated and compared with conventional machining for side milling. To determine the effects of rotary ultrasonic elliptical machining for side milling, roughness, topography, residual stress, microstructure, and microhardness of machined surface and subsurface were examined. Results show that rotary ultrasonic elliptical machining for side milling significantly improves the integrity of machined surfaces as a result of induced compressive residual stress, more pronounced plastic deformation, and work hardening of the machined surface. It was found that higher cutting speeds of up to 120 m/min and lower feed rates of approximately 0.02 mm/z achieve higher compressive residual stresses on the surface (− 221.21 MPa vs. 2.82 MPa), greater plastic deformation below the surface (up to 40 μm vs. less than 20 μm), and moderate surface work hardening (HV 425.85 vs. HV 414) using rotary ultrasonic elliptical machining for side milling compared to conventional machining for side milling. Finally, in relation to surface roughness (Ra), rotary ultrasonic elliptical machining for side milling was found to cause a slight deterioration of surface characteristics. The results of this study provide a better understanding of rotary ultrasonic elliptical machining for side milling of titanium alloy Ti-6Al-4V.