Investigation of productivity, energy efficiency, quality and cost for laser drilling

Laser drilling is a high speed, non-contact advanced machining process and has proven to be an important industrial process for producing cooling holes in various aeroengine components; in particular high-pressure turbine blades, combustor liners and nozzle guide vanes. However, an increase in the number of cooling holes demands the need for effective utilisation of laser drilling process capability. Material removal rate (MRR), specific energy consumption (SEC), hole taper and the drilling cost are the basic performance indicators to meet this goal. Hence, this research aims to examine the laser drilling process in terms of the mentioned performance measures. Taking into account the significance of material removal quantity, energy efficiency, product quality and manufacturing cost, this study is performed in the form of an experimental investigation for three laser drilling processes, namely, single-pulse drilling, percussion and trepanning. Two different laser drilling setups were prepared to produce holes in Inconel 718 superalloy sheets using flashlamp-pumped Nd:YAG laser and Quasi-CW fibre laser. This research contributes to an evaluation of the influence of laser drilling process parameters on the MRR, SEC, hole quality and drilling cost. Moreover, the performance of laser drilling methods has been compared in relation to the selected performance measures. To further understand the significance of laser sources, the performance of laser drilling was compared for the mentioned drilling setups. This research also introduced a detailed cost analysis to explore the economic implications of the laser drilling process. In addition, optimal drilling conditions were determined aiming to maximise the MRR and minimise hole taper and drilling cost.Manufacturin

Investigation of temperature in orthopaedic drilling using response surface methodology

Rise in temperature is inevitable in orthopaedic drilling. Massive research had been done in the field of orthopaedic drilling to investigate the effect of cutting conditions, bone related parameters, and drill bit geometric parameters on heat generation and minimum surrounding tissues injury. In present research, contradictory conclusions regarding the cutting conditions and drill bit geometric parameters were observed. Minimum temperature of 31°C was achieved at speed of 186 rpm, feed of 0.196 mm/rev, drill diameter of 3.85mm, and drill tip angle of 110°. Response Surface Methodology (RSM) was used to develop a mathematical model to predict the type of relationship between inputs and response. It was concluded that the most influencing parameter was drill diameter

Towards recycling cost modelling framework for carbon fibre composites

Environmental legislation puts more pressure on solving carbon fibre composites (CFC) waste management through recycling and reuse. Despite their superior properties, CFC creates environmental issue when it reaches its end of life. The aim of this paper is to to provide a framework that represents the first step towards the development of a cost modelling framework for recycling CFC materials. The focus is the mechanical and thermal (Pyrolysis) recycling process. The activities and the tasks related to each recycling process are presented. The research has been accomplished by embracing a qualitative research plan consisting of five phases. To enhance understanding of the parameters affecting the cost of the recycling process, the major and detailed cost drivers are recognised. The developed costing framework has been implemented in an IT-based cost estimation tool for easy handling and calculation of the cost parameters. This tool identifies all tasks and activities related to the two recycling processes

Experimental investigation of productivity, specific energy consumption, and hole quality in single-pulse, percussion, and trepanning drilling of IN 718 superalloy

Laser drilling is a high-speed process that is used to produce high aspect ratio holes of various sizes for critical applications, such as cooling holes in aero-engine and gas turbine components. Hole quality is always a major concern during the laser drilling process. Apart from hole quality, cost and productivity are also the key considerations for high-value manufacturing industries. Taking into account the significance of improving material removal quantity, energy efficiency, and product quality, this study is performed in the form of an experimental investigation and multi-objective optimisation for three different laser drilling processes (single-pulse, percussion, and trepanning). A Quasi-CW fibre laser was used to produce holes in a 1 mm thick IN 718 superalloy. The impacts of significant process parameters on the material removal rate (MRR), specific energy consumption (SEC), and hole taper have been discussed based on the results collected through an experimental matrix that was designed using the Taguchi method. The novelty of this work focuses on evaluating and comparing the performance of laser drilling methods in relation to MRR, SEC, and hole quality altogether. Comparative analysis revealed single-pulse drilling as the best option for MRR and SEC as the MRR value reduces with percussion and trepanning by 99.70% and 99.87% respectively; similarly, percussion resulted in 14.20% higher SEC value while trepanning yielded a six-folds increase in SEC as compared to single-pulse drilling. Trepanning, on the other hand, outperformed the rest of the drilling processes with 71.96% better hole quality. Moreover, optimum values of parameters simultaneously minimising SEC and hole taper and maximising MRR are determined using multi-objective optimisation

Investigation of electric discharge machining parameters to minimize surface roughness

: Surface roughness during electrical discharge machining (EDM) was determined, in which material is removed by thermo-electric process due to the occurrence of successive discharge between workpiece and electrode. Box-Behnken design (BBD) involving four parameters discharge current (I), Pulse ON time (PON), Pulse OFF time (POFF) and Gap voltage, with three levels was employed to minimize the surface roughness. Other parameters such as Servo speed, Polarity and Die-electric pressure were kept constant throughout the machining. A copper electrode tool was used to machine the holes in AISI 1045 steel work piece. Mathematical models were developed using Response Surface Methodology (RSM), while Analysis of variance (ANOVA) was used to observe individual effect, interaction between parameters, and to check validity of models. Results revealed that pulse on time and discharge current were two main significant parameters that statistically affected surface roughness

Performance evaluation of Cu-Ni 90/10 alloyed structures exposed to various seawater compositions and their remaining service life estimation

The Cu-Ni 90/10 alloy is extensively used in seawater applications mainly because of its excellent heat transferability, resistance toward corrosion and marine fouling. The corrosion resistance of Cu-Ni 90/10 has been found to be far superior in open natural seawater, however, several premature failures have often been reported during their exposure in the pollutant-rich seawater typically found near harbours, jetties and coastlines. This paper investigates the corrosion behaviour of Cu-Ni 90/10 alloyed coupons exposed to natural seawater, and pollutant-rich harbour seawater in a submerged position. Moreover, this research also investigates the corrosion mechanism on marine heat exchanger tubes of material that failed prematurely while operating in similar seawater compositions. The field experimental results for short-term corrosion results from coupons, and the long-term corrosion results from heat exchanger tubes have been evaluated, to formulate a relationship and corrosion modelling

Towards cost modelling for laser drilling process

Laser drilling is a widely used non-traditional machining process, in power generation and high-value manufacturing industries, to produce components such as nozzle guide vanes, combustion chambers, fuel injection nozzles and turbine blades. The operating cost of the drilling process is one of the critical factors for companies to consider to survive in the competitive global market. This research is intended to develop the cost model for laser drilling process due to its extensive application in the aerospace sector. Cost estimation facilitates the aerospace sector economically through the identification of critical parameters which act as key cost drivers and their relationship with cost. The proposed model will benefit the designers and cost engineers to have a brief overlook of cost distribution before manufacturing the component

Parametric modelling and multi-objective optimization of electro discharge machining process parameters for sustainable production

Electro Discharge Machining (EDM) can be an element of a sustainable manufacturing system. In the present study, the sustainability implications of EDM of special-purpose steels are investigated. The machining quality (minimum surface roughness), productivity (material removal rate) improvement and cost (electrode wear rate) minimization are considered. The influence and correlation of the three most important machining parameters including pulse on time, current and pulse off time have been investigated on sustainable production. Empirical models have been established based on response surface methodology for material removal rate, electrode wear rate and surface roughness. The investigation, validation and deeper insights of developed models have been performed using ANOVA, validation experiments and microstructure analysis respectively. Pulse on time and current both appeared as the prominent process parameters having a significant influence on all three measured performance metrics. Multi-objective optimization has been performed in order to achieve sustainability by establishing a compromise between minimum quality, minimum cost and maximum productivity. Sustainability contour plots have been developed to select suitable desirability. The sustainability results indicated that a high level of 75.5% sustainable desirability can be achieved for AISI L3 tool steel. The developed models can be practiced on the shop floor practically to attain a certain desirability appropriate for particular machine limits

Benchmark pre-production practice in manufacturing engineering

Prototyping stage is a very important phase of new product development, where many decisions need to be taken to get high quality, zero defect products at the right time with minimum cost. Therefore, any value added improvements or best practices in the prototyping stage will support competitiveness of manufacturing companies. This research aims to benchmark the best practices in prototype part manufacture to support early stages of product introduction. A set of of best practices in the prototype component manufacture, along with validated four step prototyping strategy model and best practice prototype journey path model were developed. Research findings provide insight about prototyping trends, best practices and optimum ways of doing prototyping in the manufacturing companies around the globe. Manufacturing companies can use the developed models and best practices to make better prototype strategy in their new product introduction system to achieve their business objectives

Challenges in cost modelling of recycling carbon fiber composites

The use of carbon fiber composites (CFCs) has become broad in many industries due to its superior properties compared to conventional materials. However, the increased demand coupled with environmental regulations has led to the development of different recycling methods for CFCs such as mechanical, thermal and chemical processes. Each recycling method has its own requirements and outputs along with some economic implications which need to be justified through cost modelling. This paper aims to identify current challenges associated with cost modelling of different processes for CFC recycling. The main challenges identified are grouped into three main categories such as technical issues, supply chain and market challenge