A vehicle routing problem solved by using a hybrid genetic algorithm

The main purpose of this study is to find out the best solution of the vehicle routing problem simultaneously considering heterogeneous vehicles, double trips, and multiple depots by using a hybrid genetic algorithm. This study suggested a mathematical programming model with a new numerical formula which presents the amount of delivery and sub-tour elimination. This model gives an optimal solution by using OPL-STUDIO(ILOG CPLEX). This study also suggests a hybrid genetic algorithm (HGA) which considers the improvement of generation for an initial solution, three different heuristic processes, and a float mutation rate for escaping from the local solution in order to find the best solution. The suggested HGA is also compared with the results of a general genetic algorithm and existing problems suggested by Eilon and Fisher. We found better solutions rather than the existing genetic algorithms.     

Effects of cutting fluids on drilling aluminium casting alloy 390

The primary objective of this research project was to compare the tool wear resulting when a semi-synthetic cutting fluid was used, to that from use of a premium soluble oil. The secondary objective was to determine the effects of cutting speed, drill diameter, and fluid concentration, on tool wear. The experiments contained two key elements: (1) cast aluminium alloy 390 was used as the workpiece material and (2) deep-hole drilling to a depth greater than two diameters was performed. Numerous drilling tests were performed with each cutting fluid using a flood application. To meet the primary objective, an experiment was designed for each cutting fluid and the wear on the lands of twist drills was measured. The secondary objective utilized a statistically-designed 2³ factorial experiment which evaluated the effects that moderate and relatively high cutting speeds, two drill diameters, and two levels of fluid concentration, had on tool wear. After analysis of the test results, it was concluded that concentration had the most significant effect on land wear when the experimentally-formulated semi-synthetic cutting fluid was used. Cutting speed was the most significant factor when drilling with the commercially-available premium soluble oil. Tool wear while using the semi-synthetic fluid was slightly less than that for the premium soluble oil.     

Rapid prototyping: Applications in academic institutions and industry

In today's competitive world, the manufacturers have to get a new and improved product to the market as fast as possible to be able to compete in the global market. The major obstacle for this task had been a long product development cycle, i.e., design, prototype manufacture and testing. The introduction of rapid prototyping (RP) in the early stages of product development has greatly reduced the development time frame and cost involved in prototype manufacturing. Furthermore, RP applications are growing very fast in such a way that it is now possible to produce parts not as prototypes, but as final parts to be used in several engineering applications. Thus, RP is now acting as a bridge to help designers, manufacturing engineers, marketing and sales personnel to provide goods timely to the customer. This paper discusses practices, current developments and future trends of RP. This paper also discusses the use and role of RP in academic institutions.     

Forming part families by using genetic algorithm and designing machine cells under demand changes

This study develops a methodology which can be used to form manufacturing cells using both a new similarity coefficient based on the number of alternative routes during machine failure and demand changes for multiple periods. The methodology is divided into two phases. A new similarity coefficient, which considers the number of available alternative routes when available during machine failure, is suggested in Phase I. The primary objective of Phase I is to identify part families based on the new similarity coefficient by using a genetic algorithm. One of the major factors contributing to the success of cell implementation is flexibility for demand changes. It is difficult to reorganize the cells according to changes in demand, available machine capacity, and due date. Most of the suggested approaches in the literature tend to use a fixed demand for cellular manufacturing systems. Due to demand changes, cell design should include more than the one period that most researchers of cellular manufacturing systems consider. A new methodology for cell formation, which considers the scheduling and operational aspects in cell design under demand changes, is introduced in Phase II. Machines are assigned to part families by using an optimization technique. This optimization technique employs sequential and simultaneous mixed integer programming models for a given period to minimize the total costs which are related to the scheduling and operational aspects.     

Effects of cutting conditions on drilling of aluminum 380

The major purpose of this project was to determine the effects of cutting conditions on drilling of aluminum alloy 380. Measurements of tool wear and surface finish were taken for two cutting speeds and feed rates, respectively. In each of the four tests, a high-helix, high-speed steel drill, 1/4 in. (6.35 mm) in diameter, was used to produce 460 holes 1.00 in. (25.4 mm) deep. The speeds used were 195 and 390 ftJmin (99 and 198 cmJs), and the feeds were 0.016 and 0.032 in.Jrev (0.406 and 0.812 mmJrev). Cutting speed had a greater influence on tool wear than feed rate. However, mean surface roughness increased approximately the same amount when the speed was doubled, as it did when the feed rate was doubled.     

Part family formation based on a new similarity coefficient which considers alternative routes during machine failure

A number of research papers have used different types of similarity and dissimilarity coefficients for determining part families. In cellular manufacturing systems, most machines are capable of performing more than one operation, which makes parts rerouting feasible. When a part is rerouted, it affects the cell performance. Most of the suggested approaches in the literature develop a new similarity coefficient based on mathematical analysis, however, these methods tend to disregard alternative routes during machine failure. The main objective of this paper is to identify part families based on a new similarity coefficient which considers the number of alternative routes available during machine failure. Based on the new similarity coefficient, the part families were identified by using a p-median model.     

Drilling models for a synthetic cutting fluid

The primary objective of this research was to develop relationships which predict tool wear from measured cutting forces. Different cutting speeds and feed rates were examined. The workpiece materials used were a medium-carbon steel and a titanium alloy. A synthetic cutting fluid was used with a 9.525 mm drill and a 6.350 mm drill, for drilling the medium-carbon steel and the titanium alloy, respectively. Preliminary testing was conducted to find the optimal values for cutting speeds and feed rates. The main drilling tests were performed using the cutting conditions resulting from the preliminary tests. Statistical analysis of the results of the main drilling tests showed that the axial force was significant at the 5 per cent level in models for both materials. It also showed that the moment about the vertical axis was significant at the 5 percent and the 15 per cent levels in the models for the titanium alloy and the medium-carbon steel, respectively. The model for the smaller holes drilled into the more homogeneous material, the titanium alloy, was more accurate in predicting tool wear.     

Introducing new parts into existing cellular manufacturing systems based on a novel similarity coefficient

Over the last three decades, designing cellular manufacturing systems (CMS) still centres on assigning machines to machine cells and parts to part families. This task ends after assigning these part families to the appropriate machine cells. In the past, testing CMS was evaluated according to the efficiency of clustering, but actual testing of CMS after installation is still unexplored. Introducing one or more new parts (products) into CMS without any changes in the installation of the cells during processing of the current parts is a new concept to be considered and evaluated. Transferring these systems from traditional ideologues to advanced ideologues (agile systems) is highly desired. This concept can be considered as part (product) flexibility in CMS. To address this concept, a new similarity coefficient between the new part and the existing manufacturing cell will be created. New productivity and flexibility measurements in CMS will also be suggested. A new strategy for accepting a new part into CMS will be proposed based on machine utilization and flexibility in the cells, cell utilization and flexibility in the system, product flexibility (system flexibility), and similarity of this part with existing manufacturing cells. A complete analytical example will be presented.     

Influence of cutting fluids on surface finish of holes drilled into aluminium 390

The primary objective of this research was to compare the surface finish resulting when using a semi-synthetic cutting fluid to that of a premium soluble oil. The secondary objective was to determine the effects of drill diameter, cutting speed, and fluid concentration on surface finish. The surface measurements were made on the walls of 6.350 and 9.525 mm lind holes drilled 25.4 mm into aluminium 390. Each cutting fluid was introduced using a flood application. Additional factors in the experimental design for each cutting fluid included two levels of cutting speed and two levels of fluid concentration. Variations in drill diameter, cutting speed, and the interaction between these factors were significant with respect to surface finish for both the semi-synthetic fluid and the soluble oil. Fluid concentration for the semi-synthetic fluid also had a significant effect on the surface finish. The surface finish produced while using the semi-synthetic fluid was approximately the same as that with the soluble oil.