A Comparison between Regular and Vibration-Assisted Drilling in CFRP/Ti6Al4V Stack

<div class="section abstract"><div class="htmlview paragraph">During mechanical assembly, individual parts are joined by different types of fasteners which are commonly to be installed into tightly tolerated holes. Drilling of widely used modern materials like CFRP and titanium leads to challenges in terms of tool and process development. A significant challenge is one step drilling in assemblies made from mixed material stacks. It results in deviating hole diameters making the additional reaming operation essential.”But also drilling of thick single material stacks imposes difficulties in terms of hole tolerance, chip extraction, heat accumulation and lubrication issues, leading to the necessity of drilling in several steps to achieve the required hole quality and integrity.</div><div class="htmlview paragraph">During orbital drilling the drive spindle rotates eccentrically in addition to tool rotation and feed movement, leading to a circular path of the cutting tool. Orbital drilling can offer advantages compared with conventional drilling and reaming. The eccentricity can be set steplessly even during the drilling process which allows to drill different hole diameters with one tool, tapered holes, change diameter within the hole or to perform a finishing cut during the tool return stroke. Tool diameter deviations also can be compensated, thus tool diameter tolerances can be enlarged and regrinding of worn tools can be applied more often, saving tool costs. The interrupted cut facilitates an extraction of the small chips, enabling drilling of closed structures without subsequent cleaning or deburring as well as one-way-assembly applications in case of blind fastener use. Damaged surfaces due to snarl chips can be avoided. Furthermore, dry drilling of aluminum material can be applied due to the reduced introduction of process heat.</div><div class="htmlview paragraph">Although already applied in several Airbus sites, the orbital drilling process still faces different challenges depending of the relevant application. In general, the radial loads on the cutting tool and machine present challenges in terms of hole tolerance when drilling high thickness / diameter ratio stacks or hole diameters below approximately ¼”. Bending of the cutting tool and vibration issues can lead to high tolerance widths and poor surface quality.</div><div class="htmlview paragraph">Due to the changed cutting kinematics compared with conventional drilling and depending of the cut material, tool and cutting parameters, the orbital drilling process introduces reduced compressive residual stresses into the hole wall, leading to a decrease of joint fatigue life. Strategies to produce orbitally drilled holes having at least the same fatigue life level compared to conventional drilling while optimizing the drilling parameters to meet engineering as well as economical requirements are going to be presented.</div></div>

<div class="htmlview paragraph">In the automotive industry there is a continual drive to reduce cost and improve processing flexibility in the assembly plants. The competitive market place demands flexible and common processes to help reduce assembly costs and improve build quality. The selection of these common processes requires experience based knowledge to pick the best practice among a set of alternatives. This paper demonstrates how math based manufacturing analysis can be used to help in this selection process.</div> <div class="htmlview paragraph">Within General Motors, the BOP (<b>B</b>ill <b>O</b>f <b>P</b>rocess) represents a globally templated approach to manufacturing and assembling vehicles. All vehicle programs are required to follow the common BOP. Broadly defined, the BOP is a set of common processing standards relating to datum number and selection, number of stations required to build a sub assembly, etc.</div> <div class="htmlview paragraph">Full implementation of the BOP allows GM to leverage resources globally, reduce manufacturing costs, and shortens the feedback cycle in our learning organization.</div> <div class="htmlview paragraph">As GM converges towards a common BOP numerous debates arise as to the suitability and selection of various processing methods. This report is an attempt to use systematic, math based, deterministic and stochastic FEA (Finite Element Analysis) methods to guide BOP development.</div>

The effect of vibratory drilling on hole quality in polymeric composites

<div class="htmlview paragraph">Aluminum and polymer composites have long been considered the materials of choice for achieving mass reduction in automotive structures. As consumer and government demand for mass reduction grows, the use of these materials, which have traditionally been more expensive than the incumbent steel, becomes more likely. In response to this growing challenge, the international steel community has joined forces to develop the Ultra Light Steel Auto Body (ULSAB). The resulting design saves mass and increases performance relative to current steel unibodies. Although mass savings are not as dramatic as those achieved by alternative materials, this design offers the potential to be accompanied by a manufacturing cost reduction.</div> <div class="htmlview paragraph">The projected manufacturing piece and investment cost for the ULSAB are investigated using technical cost modeling. The results presented here examine the elements that contribute to the cost, including treatments for stamping, hydroforming, assembly and purchased parts. Particular emphasis is placed on the procedure for laying out the design of the manufacturing and production facility based on the respective manufacturing processes, production rates, labor requirements, equipment and tooling costs, and so on.</div> <div class="htmlview paragraph">The results of this paper provide material suppliers and automakers with a framework for understanding the technical and economic advances that are possible with the implementation of the ULSAB technology approach. Through this understanding, decisions regarding investments of limited human and financial capital can be implemented.</div>

<div class="htmlview paragraph">The feasibility of a simple-cycle gas turbine engine for automobiles is analyzed by means of comparison with Otto-cycle engines for automobiles. Applicable technology is reviewed with emphasis on centrifugal compressor technology, which has demonstrated pressure ratios of better than 10:1. The design point of a simple-cycle 150 hp automobile engine based on these components is presented, together with estimated torque and fuel-flow characteristics for the entire range of possible engine performance, derived from engine-cycle analysis programs.</div> <div class="htmlview paragraph">The results of a vehicle performance computer program designed to evaluate candidates for this application include time/speed/distance performance estimates for maximum acceleration as well as fuel economy and emissions estimates for pertinent driving cycles. Summaries of manufacturing cost estimates are presented for several candidate gas turbine engines.</div> <div class="htmlview paragraph">A speculative overall cost for both four and ten years of ownership is estimated based primarily on these fuel economy and manufacturing cost derivations.</div> <div class="htmlview paragraph">It is concluded that the simple-cycle gas turbine engine studied is sufficiently attractive as a low-pollution automobile engine for the post-1975 decade to warrant full-scale demonstration as soon as possible.</div>

<div class="section abstract"><div class="htmlview paragraph">Evolving fuel efficiency and emissions standards, along with consumer demand for performance, are strong pressures for light-weighting of performance oriented motorcycles. The field of topology optimization (TO), with the extension of multi-material topology optimization (MMTO) provide manufacturers with advanced structural light-weighting methodology. TO methodology has been adopted in many industries, including automotive where light-weighting assists in meeting efficiency regulations. The development of process specific manufacturing constraints within MMTO is a critical step in increasing adoption within industries dealing with manufacturing cost restrictions. This capability can decrease design complexity, lowering manufacturing costs of optimization solutions.</div><div class="htmlview paragraph">A conventional all-aluminum perimeter style motorcycle chassis is analyzed to develop baseline compliance (total strain energy) metrics. An MMTO design space is created and optimized with steel and aluminum, such that results match the baseline design weight. This formulation demonstrates increased structural efficiency through stiffer structures at equivalent weight. Results are generated with standard MMTO, symmetry, and extrusion constraints to demonstrate utility of these manufacturing constraints. Material ratios are used to enforce lower cost material distribution selections.</div><div class="htmlview paragraph">The usage of MMTO with manufacturing and material ratio constraints has resulted in up to 60.4% reduction in structural compliance of designs, and a multitude of lower cost alternative designs. The usage of symmetry constraints provides effectively identical results to standard MMTO, with a computational time reduction of 29%. Extrusion constraints demonstrate decreased manufacturing difficulty with a computational time reduction of 52% and structural performance penalty of 58.6% from the lowest compliance MMTO result. The enforcement of steel has demonstrated a decrease in structural performance (increase in compliance) and material costs, with varying degrees depending on manufacturing constraints and enforcement limits. The MMTO based designs provide a range of solutions to designers, which can be selected based on the importance of structural efficiency, manufacturing difficulty, and material costs.</div></div>

Austenite 0Cr18Ni9Ti stainless steel is one of difficult-to-cut materials. It has poor dilling process, especially for micro-hole machining. The main reasons are the tiny drill, poor rigidity, easy to deviation. Moreover, the chip is difficult to discharge, so the drilling force is increased and the drill bit is easy to break, or even it is impossible for micro-hole drilling. In this paper, the vibration drilling process is adopted. The vibration drilling 0Cr18Ni9Ti stainless steel micro-hole process mechanism is researched. The stainless steel micro-hole drilling experiments are conducted. The results show that the vibration drilling can be a better solution for 0Cr18Ni9Ti stainless steel micro-hole processing.

<div class="section abstract"><div class="htmlview paragraph">The body structure of a vehicle is constantly under different load cases, and the spot-welded joints are usually the weakest parts, being normally oversized by the designers. This paper drives a study about the optimal number and location of the welding spots in order to improve the durability and performance of a vehicle body node, related to a specific load case. In addition, the manufacturing time and costs reduction are consequences of this optimization. Computational tools are used and a DOE (Design of Experiments) is performed to characterize the problem statistically, through a location changing sensibility analysis. A Finite Elements software was used for analyzing the stress distribution for each case. Therefore, the feasible designs will be chosen considering the best relation between performance and number of welding spots.</div></div>

<div class="htmlview paragraph">Applying FEA optimization analysis in our utility vehicle and golf car virtual prototyping has proven very useful in accelerating time to market for new product, and reducing R&D cost. This article looks at reducing manufacturing costs, correlating FEA model with field test data and diagnosing field failure root causes. The cost reduction application uses topological analysis for preliminary design and uses Goal Driven Optimization with six independent factors corresponding to two separate loads for final dimension determination.</div> <div class="htmlview paragraph">A parametric model is the basic requirement for DOE. The model can be imported from CAD directly, and it can also be created after non-parametric geometry or the initial FEA file is imported.</div>

<div class="htmlview paragraph">Aerospatiale's activities in the field of Active Thermal Control have led to the definition, manufacture and test of a new generation of radiators.</div> <div class="htmlview paragraph">The fluid loop radiator study, engaged under the Hermes programme requirements, has resulted in the definition of large radiative panels that have low mass, low manufacturing cost constraints and various possible shapes.</div> <div class="htmlview paragraph">The hybrid radiator study, with respect to the Heat Exchanger, has provided a data base of results on the wet and dry concepts.</div> <div class="htmlview paragraph">A prototype model has been defined after a “trade-off analysis” and the choice of the dry contact solution has been selected.</div> <div class="htmlview paragraph">With respect to the two phase active thermal control concept, a complete loop is under development studies.</div> <div class="htmlview paragraph">The problems of “on-ground” testing have been analysed, particularly on the condenser section; the goal being the flight performance prediction of a space radiator.</div>

<div class="section abstract"><div class="htmlview paragraph">Electric vehicles (EVs) are a promising and proven technology for achieving sustainable mobility with zero carbon emissions, very low noise pollution, and reducing the dependency on fossil fuels.</div><div class="htmlview paragraph">Global EV sales have been increasing by ~110 % since 2015, with a significant rise in 2021 (~6.75 mils EV registered) mainly led by China, the US, and Europe, amplifying the EV market share to 8.3% compared to 4.2% in 2020.</div><div class="htmlview paragraph">Future developments aimed at designing better batteries and charging technologies that reduce charging time, reduce initial battery cost, and increased flexibility. In India, EVs are emerging significantly due to stringent Carbon di Oxide (CO2) reduction drives, increasing crude oil prices, and the availability of cheaper renewable energy.</div><div class="htmlview paragraph">Leveraging government promotional policies, evolving the entire ecosystem, globally advantageous manufacturing costs, and competitive engineering skills form the perfect blend for India. To produce world-class EVs to complement the “Make in India” drive and make India the leading EV engineering and manufacturing hub for global markets.</div><div class="htmlview paragraph">This paper reviews India’s EV market potential with a key focus on the EV ecosystem, including EV commodities infrastructure, supplier plans, and government initiatives to enhance EVs in India with statistical data and reports from research papers.</div></div>

<div class="htmlview paragraph">Global industry is faced with the competitive pressures of producing quality parts at lower costs while implementing increasingly sophisticated designs. Time is the common enemy- we must do things better and faster.</div> <div class="htmlview paragraph">Previous computer technology could not address these problems in a cost-effective manner. Recent improvements in software, hardware and interfacing have improved the quality and reduced the costs of design and manufacturing.</div> <div class="htmlview paragraph">This paper describes the application of modern CAD/CAM technology to the sealing products industry.</div>

This work aims to apply Acoustic Emission to monitor the drilling process in carbon fibre laminates. Continuous Acoustic Emission data is captured over the entire drilling process of a through hole. The use of continuous acoustic emission data acquisition allows the identification of lower frequency periodic temporal features related to the cutting process. A new approach to data analysis is presented that utilises an enveloping technique to study these periodic phenomena and show that they correlate to changes in cutting regime as tool wear advances and hole quality reduces. This analysis of Acoustic Emission data is supported by the measurement of tool temperature, thrust force and the assessment of hole quality. Results show that Acoustic Emission activity is correlated to changes in the cutting process, and a correlation between tool wear and Acoustic Emission is observed. This correlation has been confirmed by corresponding increases in thrust force and drill temperature, with a consequent decrease in the observed hole quality.

Comparative evaluation of hole making processes in magnesium alloy AZ31 under dry machining condition

In aluminium matrix composites, reinforcement of hard ceramic particle present inside the matrix which causes tool wear, high cutting forces and poor surface finish during machining. This paper focuses on effect of cutting parameters on thrust force, surface roughness and burr height during drilling of MMCs. In the present work, discuss the influence of spindle speed and feed rate on drilling the pure base alloy (Al-2219), mono composite (Al- 2219+8% B4C) and hybrid composite (Al-2219+8%B4C+3%Gr). The composites were fabricated using liquid metallurgy route. The drilling experiments were conducted by CNC machine with TiN coated HSS tool, M42 (Cobalt grade) and carbide tools at various spindle speeds and feed rates. The thrust force, surface roughness and burr height of the drilled hole were investigated in mono composite and hybrid composite containing graphite particles, the experimental results show that the feed rate has more influence on thrust force and surface roughness. Lesser thrust force and discontinuous chips were produced during machining of hybrid composites when compared with mono and base alloy during drilling process. It is due to solid lubricant property of graphite which reduces the lesser thrust force, burr height and lower surface roughness. When machining with Carbide tool at low feed and high speeds good surface finish was obtained compared to other two types of cutting tool materials.