A robust design methodology suitable for application to one-off products

Robust design is an activity of fundamental importance when designing large, complex, one-off engineering products. Work is described which is concerned with the application of the theory of design of experiments and stochastic optimization methods to explore and optimize at the concept design stage. The discussion begins with a description of state-of-the-art stochastic techniques and their application to robust design. The content then focuses on a generic methodology which is capable of manipulating design algorithms that can be used to describe a design concept. An example is presented, demonstrating the use of the system for the robust design of a catamaran with respect to seakeeping

Case study in six sigma methadology : manufacturing quality improvement and guidence for managers

This article discusses the successful implementation of Six Sigma methodology in a high precision and critical process in the manufacture of automotive products. The Six Sigma define–measure–analyse–improve–control approach resulted in a reduction of tolerance-related problems and improved the first pass yield from 85% to 99.4%. Data were collected on all possible causes and regression analysis, hypothesis testing, Taguchi methods, classification and regression tree, etc. were used to analyse the data and draw conclusions. Implementation of Six Sigma methodology had a significant financial impact on the profitability of the company. An approximate saving of US$70,000 per annum was reported, which is in addition to the customer-facing benefits of improved quality on returns and sales. The project also had the benefit of allowing the company to learn useful messages that will guide future Six Sigma activities

A multi-sensor based online tool condition monitoring system for milling process

Tool condition monitoring has been considered as one of the key enabling technologies for manufacturing optimization. Due to the high cost and limited system openness, the relevant developed systems have not been widely adopted by industries, especially Small and Medium-sized Enterprises. In this research, a cost-effective, wireless communication enabled, multi-sensor based tool condition monitoring system has been developed. Various sensor data, such as vibration, cutting force and power data, as well as actual machining parameters, have been collected to support efficient tool condition monitoring and life estimation. The effectiveness of the developed system has been validated via machining cases. The system can be extended to wide manufacturing applications

Variation of Process Parameters Using the Taguchi Method

As of late, RPT has been executed in the industry, especially in the areas of product development. Existing methods give the ability to quickly create a substantial strong part, specifically from three dimensional Computer Aided Design (CAD) information, from a scope of materials, for example, photo curable resin, powders and paper. Much of the time, the final result of a formative cycle is a metallic object with dimensionally steady and of high precision, whether it is a part or a device. Part testimony introduction is vital variable of layered assembling as it impacts fabricate time, bolster structure, dimensional exactness, surface complete and expense of the model. Various layered assembling procedure particular parameters and imperatives must be considered while choosing the part statement introduction. Determination of an ideal part affidavit introduction is a troublesome and prolonged errand as one needs to exchange off among different negating destinations like part surface complete and construct time. It is referred to those process parameters, for example, the air gap between adjoining tracks, raster point, thickness, width of kept layers impact the execution of parts created on a FDM machine. From the outcomes, it is discovered that FDM parameters, i.e. layer thickness, raster edge and air gap altogether influence the versatile execution of the compliant ABS model. The ideal levels of parameters at diverse edge of removal are likewise introduced. Nevertheless, the suitable levels of parameters connected with diverse execution criteria still need further examination. A few studies have been directed to focus the ideal parameters of FDM, and execution criteria frequently utilized incorporate form time, quality, sturdiness and surface trustworthiness of the models, typically for infusion trim and tooling applications

The application of multi-objective robust design methods in ship design

When designing large complex vessels, the evaluation of a particular design can be both complicated and time consuming. Designers often resort to the use of concept design models enabling both a reduction in complexity and time for evaluation. Various optimisation methods are then typically used to explore the design space facilitating the selection of optimum or near optimum designs. It is now possible to incorporate considerations of seakeeping, stability and costs at the earliest stage in the ship design process. However, to ensure that reliable results are obtained, the models used are generally complex and computationally expensive. Methods have been developed which avoid the necessity to carry out an exhaustive search of the complete design space. One such method is described which is concerned with the application of the theory of Design Of Experiments (DOE) enabling the design space to be efficiently explored. The objective of the DOE stage is to produce response surfaces which can then be used by an optimisation module to search the design space. It is assumed that the concept exploration tool whilst being a simplification of the design problem, is still sufficiently complicated to enable reliable evaluations of a particular design concept. The response surface is used as a representation of the concept exploration tool, and by it's nature can be used to rapidly evaluate a design concept hence reducing concept exploration time. While the methodology has a wide applicability in ship design and production, it is illustrated by its application to the design of a catamaran with respect to seakeeping. The paper presents results exploring the design space for the catamaran. A concept is selected which is robust with respect to the Relative Bow Motion (RBM), the heave, pitch and roll at any particular waveheading. The design space is defined by six controllable design parameters; hull length, breadth to draught ratio, distance between demihull centres, coefficient of waterplane, longitudinal centre of floatation, longitudinal centre of buoyancy, and by one noise parameter, the waveheading. A Pareto-optimal set of solutions is obtained using RBM, heave, pitch and roll as criteria. The designer can then select from this set the design which most closely satisfies their requirements. Typical solutions are shown to yield average reductions of over 25% in the objective functions when compared to earlier results obtained using conventional optimisation methods

Mono and Multi-Objective Optimization and Modeling of Machining Performance in Face Milling of Ti6Al4V Alloy

Titanium alloys are extensively used in numerous industries like aerospace, automotive, military, etc., due to their exclusive characteristics. But machining these alloys has always been challenging for manufacturers. This research investigates the effect of radial depth of cut on cutting forces, tool life, surface roughness (Ra), and material removal rate (MRR) during face milling of Ti6Al4V alloy. It also aims to perform mono and multi-objective optimization of response characteristics to determine the optimal input parameters, namely cutting speed, feed rate, and radial depth of cut. Taguchi method and analysis of variance (ANOVA) have been used for mono-objective optimization, whereas Taguchi-based Grey relational analysis (GRA) and Genetic algorithm (GA) have been used for multi-objective optimization. Regression analysis has been performed for developing mathematical models to predict Ra, tool life, average cutting forces, and MRR. According to ANOVA analysis, the most significant parameter for tool life is cutting speed. For MRR and average cutting force (Avg. FY), the most influential parameter is the radial depth of cut. On the other hand, feed rate is the most significant parameter for Ra and average feed force (Avg. FX). The optimal combination of input parameters for tool life and Avg. FY is 50 m/min cutting speed, 0.2 mm/rev feed rate, and 7.5 mm radial depth of cut. However, the optimal parameters for Ra are 65 m/min cutting speed, 0.2 mm/rev feed rate, and 7.5 mm radial depth of cut. For Avg. FX, the optimal conditions are 57.5 m/min cutting speed, 0.2 mm/rev feed rate, and 7.5 mm radial depth of cut. Similarly, for MRR, the optimal parameters are 65 m/min cutting speed, 0.3 mm/rev feed rate, and 12.5 mm radial depth of cut. A validation experiment has been conducted at the optimal Ra parameters, which shows an improvement of 31.29% compared to the Ra measured at the initial condition. A minor error has been found while comparing the experimental data with the predicted values calculated from the mathematical models. GRA for multi-objective (3 objectives: tool life, Ra, and Avg. FY) optimization has improved 55.81% tool life, 6.12% Ra, and 23.98% Avg. FY. ANOVA analysis based on grey relational grade has demonstrated that radial depth of cut is the most significant parameter for multi-objective (three objectives) optimization during the face milling of Ti6Al4V. The results obtained from the GRA considering four output characteristics (tool life, Ra, Avg. FY, and MRR) are compared with GA optimization results for both roughing and finishing, and a negligible deviation has been observed

Octree-based production of near net shape components

Near net shape (NNS) manufacturing refers to the production of products that require a finishing operation of some kind. NNS manufacturing is important because it enables a significant reduction in: machining work, raw material usage, production time, and energy consumption. This paper presents an integrated system for the production of near net shape components based on the Octree decomposition of 3-D models. The Octree representation is used to automatically decompose and approximate the 3-D models, and to generate the robot instructions required to create assemblies of blocks secured by adhesive. Not only is the system capable of producing shapes of variable precision and complexity (including overhanging or reentrant shapes) from a variety of materials, but it also requires no production tooling (e.g., molds, dies, jigs, or fixtures). This paper details how a number of well-known Octree algorithms for subdivision, neighbor findings, and tree traversal have been modified to support this novel application. This paper ends by reporting the construction of two mechanical components in the prototype cell, and discussing the overall feasibility of the system

Concurrent engineering and design for manufacture in the medical device industry

Concurrent Engineering (CE) is an approach to product development in which engineers work on design and manufacturability at the same time. The ultimate goal of concurrent engineering is to reduce the time-to-market while improving quality. This thesis goes into details about the tools necessary to achieve successful product development in the Medical Device Industry. The novelty of this thesis is not in the tools themselves but rather in the way that they are applied to the medical device industry. The need for the CE approach is of utmost importance because of the vast competition in the medical device industry. The times now require changes. These changes are depicted in detail early in this thesis. This latter suggests that manufacturing is to be perceived like another science. The axiomatic approach to manufacturing answers these needs. A new way of designing a product and collecting data is relevant. It is known as the technique of Quality function Deployment (QFD). Finally, all these tools are managed with the phase approach to management. I sincerely think that this thesis will constitute an invaluable tool for managers and engineers in the medical industry

Development of Friction Flash to Tube (F2T) and application to S355 grade steel

Friction Flash to Tube (F2T) is an innovative friction based manufacturing technique to produce seamless tubes based on open die forging, invented at Aalto University. These tubes can be produced economically in small sizes and batches, envisaging applications of high value materials that are not available in the market. The objective of this Master thesis was to develop the experimental condition of F2T as well as the proper parameters in F2T by approaching Taguchi method. The pre-defined parameters to investigate in Taguchi method were established as forging force, tool rotation and initial transient plunging depth and the investigating of geometrical and metallurgical characteristics were done. Cold rolled high strength and low alloy structural steel S355 is the material used in this research work. The parameters of the F2T process were developed based on design of experiments, with geometrical and hardness properties as performance parameters. The optimized conditions and parameters were applied to produce tubes for extensive evalua-tion of the mechanical and metallurgical material properties. The F2T process has specific components and control demands that cannot be met by the existing manufacturing systems. This challenge was overcome by developing one first version of a dedicated system based on an existent Friction Stir Welding equipment. One additional challenge was to produce tubes longer than 40 mm because of buckling. The buckling was prevented by implementing a lateral support system constraining the consumable rod during the initial transient plunging period. The test specimens for extensive mechanical test and metallurgical analysis were extracted from tubes produced with 80 mm in length. These longer tubes were manufactured using the support system to prevent buckling. The results on tensile test, flattening test and flare test of F2T tube reveal that the mechanical properties of produced tubes are as good as tube of similar material produced by another manufacturing technique. The temperature during the application of the F2T process was monitored with thermo-couples. The mechanical properties of produced tubes were evaluated by hardness meas-urement of cross and longitudinal sections. Tensile test were applied to sub-sections of wall of the tubes, and flare and flattening test to the whole tubes. The metallurgical analysis encompasses optical microscopic analysis, and SEM/EBSD with grain size evaluation. The research work demonstrate the feasibility of producing seamless tubes by F2T in structural steel. A correct design of a dedicated system to prevent the buckling, enables to produce long tubes