Manufacture Of Mechanical Parts Research Articles

Experimental Investigation to Optimize Build Orientation and Raster Angle for PLA and ABS Specimens Generated by FDM Technology

The fused deposition modeling (FDM) process is used increasingly in the manufacture of mechanical parts and more particularly in the automotive and aeronautical fields. The purpose of this work is to optimize build orientation for obtaining polylactic acid (PLA) and acrylonitrile butadiene styrene (ABS) samples with the best mechanical properties, dimensional accuracy, surface quality, and minimal total cost. For achieving This, PLA and ABS specimens are fabricated by FDM technology with three build orientations (flat, on edge, upright) and three raster angles (0°, 45°, 90°).at first, the dimensions of the produced samples are measured .secondly, the tensile test, DETLAB equipment was used to obtain tensile stress. In addition, roughness testers were also used to measure surface quality. As a consequence, the findings indicate that the mechanical strength increases with decreasing raster angle and by aligning from upright to flat orientation for both materials due to the fracture mechanism and loading direction. Also, the manufacturing orientation and raster angles significantly affected the dimensional accuracy and total cost. Additionally, there was a big difference in the surface roughness depending on the manufacturing orientation and raster angle; perpendicular measurements increase surface roughness values. We aim to investigate the impact of flat, on-edge, and upright build orientations as well as raster angles on the total cost, tensile strength, dimensional accuracy, and surface roughness of PLA and ABS material through tensile experiments.

MANUFACTURING OF RAPID PROTOTYPES OF MECHANICAL PARTS USING REVERSE ENGINEERING AND 3D PRINTING

This article focuses on the design and manufacture of mechanical parts that have complicated shapes using the technique of reverse design using a scanner or an MMT for data acquisition in the form of a point cloud, using CAD software (CATIA). The digital model created is used for a virtual representation of the final product. Then we get the physical model on a 3D printer (also called additive manufacturing process) for later use in sand moulds. To have the imprint in the sand mould, we go through the fusion of the physical model (part). The use of this technique in the industry, allows us to save a lot of time in terms of model preparation and simple to implement, especially if it is mechanical parts that do not have a definition drawing, or they are worn out, then structural analysis was applied on the model using FE based software and tools to prove the quality of the product. Von Mises equivalent strains and stresses were predicted and decreased with increasing areas and honeycomb thickness. The objective of this article is to give an overview of this relatively modern technology and its various applications.

A Kind of Filling Lattice Structure Based on DFAM for Mechanical Parts: The Diamond Lattice Structure

Thanks to the geometric and material complexity of additive manufacturing, the design space of mechanical parts has been developed, in which lattice filling structure customization can be applied to the solid filling of mechanical parts to achieve the goal of mechanical structure lightweight. A kind of diamond lattice structure unit is designed by imitating the natural method based on Design for Additive Manufacturing of mechanical parts. The mathematical model of the relative density and mechanical properties of the unit are established, and the relationship between the two is obtained, which is verified by simulations; then the relatively uniform results are obtained. The variable density hypothesis of diamond lattice structure is proposed, the methods of simulations and compression tests are used to verify the hypothesis, and the results show that the variable density structure with the density of the filling element decreasing gradually with the stress point as the center has better compression performance and concurrently verify the correctness and applicability of the equivalent modulus of elasticity mathematical model. The results of this study can be applied to the solid sandwich filling of pressure mechanical parts, and the stress density matching relationship can be carried out to further specific design.

Effect of Elevated Temperature on Bending Fatigue Behavior for Neat and Reinforced Polyamide 6,6

Recently, considering polymer composite in manufacturing of mechanical parts can be caused a fatigue failure due to the very long time of exposure to cyclic loading and may at environmental temperatures higher than their glass transition temperature; therefore, in this paper, a comprehensive investigation for bending fatigue behavior at room and elevated temperatures equal to 60 °C, 70°C, and 80 °C will be done. Rotating bending test machine was manufactured for this purpose supplied with a connected furnace to perform fatigue tests at elevated temperatures. The obtained results appeared that the increase in applied stress and temperature caused a clear reduction in fatigue life; also the addition of carbon nanotubes enhanced the fatigue life at different temperatures by 183%, 205%, 218%, and 240%, respectively while the addition of short carbon fibers improved fatigue life by 324%, 351%, 387%, and 415%, respectively. As well as, Polyamide 6,6/carbon fiber composite appeared fatigue limit at temperatures equal to 20°C and 60°C and stresses approximately equal to 55 MPa and 38 MPa respectively.

Rapid prototyping methods for the manufacture of fuel cells

The term rapid prototyping (RP) is widely used to describe technologies which create physical prototypes directly from digital data. The first methods for rapid prototyping became available in the late 1980s and were used to produce models and prototype parts. Three-dimensional (3D) rapid prototyping methods are widely employed in various areas of manufacturing, research, and education. Typical applications include engineering, architecture, and medicine. The present level of technical and commercial demand requires the development of faster and cheaper methodologies for the design and execution of structures. Various techniques based on CAD platforms and rapid prototyping are available. Parts can be produced in a variety of materials: polymers, metal, paper, ceramics, and composites.The RP method also enables the production of prototypes useful for analysing the characteristics of a complex system (e.g. interference between dynamic parts, geometric evaluation, quality, and reliability). RP technologies can produce very complex parts which are impossible or difficult to produce by traditional methods.This paper presents typical applications of rapid prototyping technology for the manufacture of mechanical parts for fuel cells, such as housing parts or bipolar plates which supply reactants (hydrogen to anodes and oxygen to cathodes), conduct electrons from one cell to the next, remove waste heat from cells, and provide mechanical support for cells in a stack. Conventional graphite or composite materials can be replaced by lighter metallic materials characterised by vastly superior manufacturability and cost effectiveness, greater mechanical strength, increased durability and resistance to shock and vibration, and zero permeability.The potential for the application of this method for the manufacture of metallic bipolar plates (BPP) for use in proton exchange membrane fuel cells (PEMFCs) is presented and discussed. Special attention is paid to the fabrication of light elements for the construction of PEMFC stacks designed for mobile applications such as aviation technology and unmanned aerial vehicles (UAVs).

Experimental investigation of the tribological behaviour of carbon and low-alloy steels sliding against HSS

ISO 42CrMo4 low-alloy steel and ISO C45 carbon steel are commonly used in the manufacture of mechanical parts, which are continuously subjected to friction and wear. The effect of microstructure changes during functioning on the tribological behaviour of these steels was evaluated under unlubricated and reciprocating sliding conditions. The diverse microstructures are obtained by varying the heat treat- ment conditions. The mechanical behaviour of the diverse obtained microstructures was investigated via hardness measurements and tensile tests. Results showed that there is no correlation between friction properties and mechanical ones. Wear properties depend on hardness but no correlation is obtained be- tween wear properties and work hardening ones. Increasing normal load decreased friction properties but increased wear properties.

Design Verification through Tolerance Stack up Analysis of Mechanical Assembly and Least Cost Tolerance Allocation

Geometric dimensioning and Tolerancing (GDT) constitutes the dominant approach for design and manufacture of mechanical parts that control inevitable dimensional and geometrical deviations within appropriate limits. The stack up of tolerances and their redistribution without hampering the functionality is very important for cost optimization. This paper presents a methodology that aims towards the systematic solution of tolerance stack up problem involving geometric characteristics.Conventional tolerance stack up analysis is usually difficult as it involves numerous rules and conditions. The methodology presented i.e. generic capsule method is straightforward and easy to use for stack up of geometrical tolerances of components and their assembly using graphical approach. In the work presented in this paper, angularity tolerance has been considered for illustration of the methodology. Two approaches viz. Worst Case (WC) and Root Sum Square (RSS) have been used. An example of dovetail mounting mechanism has been taken for purpose of stack up of angularity. Based on the stacked tolerance, it can be verified with the design tolerance of the assembly. Based on the comparison, designer has to reassign the appropriate tolerances to fulfil the functionality if required. If the stacked tolerance is as per designer requirement, then reallocation of tolerances on individual components should be done. Costs versus tolerance data are available for each component. With optimization technique, the optimized cost has been calculated for the assembly.

Tolerance Stack up Analysis for Angularity of Components and their Assembly

Geometric dimensioning and Tolerancing (GDT) constitutes the dominant approach for design and manufacture of mechanical parts that control inevitable dimensional and geometrical deviations within appropriate limits. The stack up of tolerances and their redistribution without hampering the functionality is very important for cost optimization. This paper presents a methodology that aims towards the systematic solution of tolerance stack up problem involving geometric characteristics.Conventional tolerance stack up analysis is usually difficult as it involves numerous rule and conditions. The methodology presented i.e. generic capsule method is straightforward and easy to use for stack up of geometrical tolerances of components and their assembly using graphical approach. In the work presented in this paper, angularity tolerance has been considered for illustration of the methodology. Two approaches viz. Worst Case (WC) and Root Sum Square (RSS) have been used. An example of dovetail mounting mechanism has been taken for purpose of stack up of angularity. This assembly consists of two parts i.e. dovetail male and dovetail female. Tolerance stack up has been done both for the components and their assembly. Need for computerisation of methodology for geometrical tolerance stack up of large assemblies has emerged out as the limitation of the proposed method.

Geometrical position tolerance assignment in reverse engineering

Geometric dimensioning and tolerancing constitutes the dominant approach for design and manufacture of mechanical parts that control inevitable dimensional and geometric deviations within appropriate limits. Position tolerance is a critical geometric tolerance very frequently used in industry. Its designation requires size data in conjunction with appropriate datums and location coordinates for the position. In reverse engineering, where typically relevant engineering information does not exist, conventional, human-based, trial and error approach for the allocation of positional tolerances requires much effort and time and offers no guarantee for the generation of the best results. This is mainly due to the large number of possible data combinations and the applicable relationships that have to be developed and processed. A methodology that aims towards the systematic solution of this problem in reasonable computing time and provides realistic and industry approved results is presented, demonstrated and discussed in the paper.

Virtual Technology Based Associative Integration of Modeling of Mechanical Parts

Advanced application of powerful computer tools at engineering design of advanced products related activities means creating integrated product models in advanced computer systems. Leading application oriented master model concepts and standards as STEP serve this purpose. Engineers are working simultaneously on product design. Results of engineering decisions are analyzed for loads, aesthetics and manufacturability. Product design, results of analyses, processes of manufacturing of parts and much more are described in integrated product model. This model is accessed by several engineers simultaneously and is communicated with other engineering design environments. Because most of prototype development activities are being moved into computer systems, advanced modeling is often cited as virtual pro-, totyping. This paper summarizes and relates some advanced modeling approaches and methods to emphasize main trends in fulfilling demands for modeling tools in the early 21th century. As one of the key issues a manufacturing process model associative with form feature based part model is introduced. This model was proposed by the authors. The motivation is that low level integration of design and manufacturing of mechanical parts is still a main drawback of efficient application of expensive modeling systems. The proposed method ’allows for creating part models simultaneously with their analysis of machineability. In this paper chapter 2 outlines the scene of modeling based decision making of engineers as well as levels of product model creation. Chapter 3 explains the prevailing modeling principles, while chapter 4 emphasizes structure descriptions. In chapter 5 the proposed associative, Petri net model representation based manufacturing process modeling and its potential applications are explained are detailed. Two additional key subject areas are discussed in chapter 6 and chapter 7, namely effects of globalization on modeling and product data management. The main aspect of discussion is model and communication based group work of engineers.

Selected Papers INES2000

In engineering practice we often have to deal with complex systems, where the conventional approaches for understanding and predicting the behavior of the system can prove to be inadequate. Hence, the researchers try to put some intelligence into the system. The term intelligence in this context still more or less remains a mysterious phenomenon and can be characterized by different abilities of the system or machine, such as adaptation, decision-making, learning, recognition, diagnostics, autonomy, etc. Many of the new results related to this area are published in Journals and in International Conference Proceedings. One such conference is the "IEEE International Conference on Intelligent Engineering Systems". The fourth conference in this series (INES 2000) took place in Portoroz, Slovenia, on September 17-19,2000. There were around eighty participants from eighteen countries around the world. We are glad that so many authors have contributed to ideas related to the issues at the conference. Many of the papers were about applications and design, and others on more theoretical aspects of intelligent systems. This variety made the selection of papers for this special issue very difficult. Eight papers have been selected in the end, which cover different aspects of intelligent engineering systems. It should be pointed out that the respective authors were also kind to revise and update the presented papers for this special issue. The first paper deals with the manipulation problem where the motion changes depending on the state of the system as it is the case in the finger gaiting applications. To solve it the semi-stratified control theory using smooth motion planning is used. The proposed concept combines the stratified motion planning with the unconstrained finger allocations. In the second paper a special branch of Soft Computing developed for the control of mechanical devices is described. It reduces the number of free parameters and computational complexity. For illustration of the efficiency of the proposed adaptive control, a simulation of polishing with a 3 DOF robot is given. The next paper discusses the force control of redundant robots in an unstructured environment. A special attention is given to the decoupling of the task space and null space motion. For that the minimal null space approach is used. The proposed impedance controller assures good task space performances and minimizes the disturbances caused by obstacles. The performance of the proposed controllers has been evaluated by the simulation and by experiments on a real robot. The forth paper presents some advanced modeling approaches and methods. As one of the key issues a manufacturing process model fully associative with form feature based part model has been introduced. The motivation has been that the low level integration of design and manufacturing of mechanical parts, as identified by the authors, is still a main drawback of efficient application of expensive modeling systems. The proposed method allows for creating part model simultaneously with their analysis of machineability. The next paper discusses the design of fractal-order discrete-time controllers. Some approaches to implement fractal derivatives and integrals are analyzed. As the application of the theory of fractional calculus is rather new, many aspects remain to be investigated. The sixth paper demonstrates how to map classical dictionaries and similar structured data to a hypertext structure that is more suitable for the modern media. To achieve the new shape automatically, the HiLog language is used. The automated mapping is illustrated by an example based on Oxford Dictionary of Modern English. In the seventh paper a humanoid robotics shoulder is compared to the human shoulder. First, the capabilities of the robotics shoulder are analyzed and next, using the optical measurement system the human shoulder movements have been measured and analyzed. The last paper discusses the bias-variance tests on multi-layer perception. The performance of Bayesian neural networks is compared with the performance of neural networks trained with a gradient method. Additionally, it is analyzed if it is possible to use a number of networks in committee trained with gradient descent to achieve the performance of a Bayesian network.

Descriptive Geometry in Engineering

ORTHOGONAL projections are commonly used for representing three dimensional figures on a sheet of paper, and their object is usually that of conveying shape and dimensions to craftsmen, in order to permit manufacture of mechanical parts.