


Politecnico di Torino  
Academic Year 2017/18  
01NLFJM Fundamentals of machine design and drawing 

1st degree and Bachelorlevel of the Bologna process in Mechanical Engineering  Torino 





Subject fundamentals
The aim of the course is to provide the skills and knowledge necessary for the design and verification of mechanical elements, using both traditional and numerical methods and to produce 2D and 3D CAD models and drawings of components and mechanical systems with particular reference to the problems of dimensional and geometric tolerances.
The topics covered are:  integration of structural mechanics (residual stress, variable amplitude fatigue and basic multiaxial fatigue;  principles and procedures for design and verification of some of the major elements of machines and joints (axes and shafts, axial symmetric solids, hubshaft connections, bearings, springs, threaded fasteners and bolts, welded joints);  principles and rules of dimensional and geometric tolerancing, criteria for their control and methods for stackup analysis;  methods for functional representation and simulation of industrial projects 
Expected learning outcomes
Knowledge and understanding of mechanical design principles and specific design methodologies for some elements of machines and mechanical joints on the basis of the principal standards;
Knowledge of methods of functional representation and simulation of industrial projects; Knowledge of Geometric Dimensioning and Tolerancing (GD & T) and of the stackup problems; Ability to perform the design and verification of mechanical elements and connections (axes and shafts, axisymmetric solids, hubshaft connections, bearings, springs, threaded fasteners and bolts, welded joints); Ability to produce manual sketch drawing 2D, computer assisted 3D model and drawing with functional dimensioning by using dimensional and geometric tolerancing in stackups. 
Prerequisites / Assumed knowledge
Knowledge of mechanical engineering drawing according Standards ISO ' ANSI. Ability to interpret drawings of details and assembly. Experience with software CAD 3D.
Ability to carry out the kinematic analysis of simple mechanisms, ability to perform the calculation of stresses in simple mechanical components and to perform static and fatigue verifications, knowledge of the main thermal treatments. 
Contents
The aim of the course is to provide the minimum skills and knowledge necessary for the design and verification of mechanical elements and it represents the straight development and insight of the contents of the course Fundamental of Strenght of Materials towards applications of machine design. The course benefits of the subjects included in the course of Engineering Drawing for the part related with the graphical representation and functional drawing of machine elements.
Technical drawing and calculations for the design of machine elements are combined and developed for all the machine elements typical of the machine design subjects. This course is organized in two parts: In the first part, the strength of machine elements is taken into account by means of calculations and design procedure against static and dynamic (fatigue) stress. The commonest machine elements and joint elements are considered. Lectures will give a straight presentation of relevant topics to be studied to perform design of machines through verification of the components and of the system. Practice hours will be offered to solve examples, numerical exercises and practical cases, practice with machine design and tools, and an exam simulation. In the second part Machine Design topics are introduced by means of examples and applications based on the GD&T (Geometric Dimensioning and Tolerancing) which allows to specify the requirements and functional constraints for the specific shape, aiming at obtaining the best quality (tradeoff of cost and performance) of machine elements for which preliminary Geometric Dimensioning is performed. • Machine Design o Course introduction: contents, basic knowledge requirements, classes, practice (exercise), exam (1 h). o Fatigue: stress concentration, basic concepts, engineering fatigue diagrams, fatigue life and fatigue strength influencing factors, multiaxial loading, components safety (9 hours). o Spindles and shafts: stress states, computation and verification methods (3 hours). o Gearing: basics, tooth geometry, force calculation, determination of meshing forces and stress loading for spur and helical gears (2.5 hours). o Stress state for contact loads: basics of Hertz theory and applications (design procedures and fatigue verification according to AGMA standards) (2.5 hours). o Axisymmetric solids: stress state in thin walled tubes subjected to pressure load, stress field in axisymmetric solids, tubes and thick walled pressure vessels. (3.5 hours). o Hubshaft fitting: interference assembly, use of ISO tolerancing tables for stress state calculation, connecting elements, Shafthub connections by keys, splines, pins, etc. (4.5 hours). o Bearings: types, catalogue selection, endurance evaluation, mounting solutions (3.5 hours). o Shaft joints and clutches: main connection methods, permanent and moveable (6.5 hours). o Threaded connections: description and standards, interference diagrams, stresses in the threaded connectors, effect of external loading, uncertainty and loosening, antiloosing methods, static and fatigue verifications (4.5 hours). o Welding: processes and methods, types of welding, static and fatigue verifications with Eurocodes, variable loading, Miner rule. (4.5 hours). o Springs: types of springs, applications, utilization factor, springs in series and in parallel, torsion springs, leaf springs, static and fatigue verification (4.5 hours). o Tutoring, course completion, example of a test exam (4.5 hours). • CAD o Objectives, Contents, CAD exam procedure; CAX environment; Design and Mechanical Components, (1.5 hours) o Mechanical Design Steps and Mechanical Drawing Review: 2D Drawings Basic concepts, Dimensioning components and assemblies, projections (1.5 hours) o Reading Drawings: assemblies and parts components identification (1.5 hours) o GD&T (1.5 hours) o Overview on Solidworks modelling: Sketches, parts, assemblyes, drawings (1.5 hours) o Parts modelling: sketches functions and examples (3 hours) o Solidworks drawings: projections, dimensioning GD&T, examples (1.5 hours) o Commercial components selections: how to read a catalogue and select the proper components (1.5 hours) o Manufacturing processes: machining, rapid prototiping, additive manufacturing (3 hours) o Solidworks Simulation overview (1.5 hours) 
Delivery modes
At the end of the course, the student gains the knowledge of the commonest machine components used in the mechanical field and a variety of constructive solutions for each topics included in the course. Preliminary dimensioning and verifications and the skill of representing in a clear way what he calculated are also objectives of the course.
It is expected that the student achieves specific skills such as: 1. To perform preliminary verification and dimensioning calculations on the main machine components, with the aid of tables, diagrams and formulas from technical codes and standards; 2. To read and understand drawings of assembly of medium complexity and understand how the represented devices work; 3. To use of parametric 3D software (Solidworks) for the generation of parts and assemblies and for the generation of 2D drawing of features of the components; 4. To represent every components with the correct GD&T nomenclature in order to limit geometrical and dimensional imperfections and to guarantee a proper operation in service. The knowledge of the basic concepts, of the experimental techniques and of the technological framework at the origin of the theory, standards, and simplifying assumptions, constitutes a main part of the professional background even if it is not described in a mathematical form. These aspects are therefore part of the lectures which are divided into three parts: • Assisted exercises on the topics of machine design: The ability to solve real problems that an engineer must face in his professional life is achieved by developing the ability to apply theoretical models to practical applications. Thus, exercises for the part of machine design propose simple but realistic problems whose objective is to lead the student to a full comprehension of the theoretical basis to use it in everyday professional life. Exercises allow to get the sensitivity of the order of magnitudes of the values that are calculated on the final result. In this sense it is vividly suggested, during the lectures where exercises are presented and during the written part of the final exam, to also use graphical solutions also and to perform the analysis of the dimension units in order to avoid wrong conclusions determined by computation errors. Exercises will be shown and solved partly by the teacher and partly by students during the classes dedicated to this part. • Applied CAD laboratory: the drawing skills and technique will be applied to generate models of a series of mechanical systems in the LAIB of the Politecnico. Exercises are meant to let the students understand existing mechanical drawings and to allow students to gain the most advanced techniques of current CAD software (Solidworks) and necessary to generate and modify 3D assemblies of medium complexity. Depending on the availability of the seats in the LAIB, this laboratory may be developed in teamworking, by teams of maximum 3 students. Each student shall contribute equally to the development of the series of drawings. • Homework project: the development of a mechanical system project aims at approaching the professional life of a mechanical engineer. One or more parts of a mechanical system (usually a transmission line for speed reduction) will be designed. All the various parts (gears, shafts, supports, connections, etc.) will be subject to verification for strength, in static loading and fatigue, to insure an adequate level of safety against failure. The system will be drafted together with the details of the parts that compose the system. This homework project will be developed in teamworking, by teams of 3 students. Each student shall contribute equally to the development of the project, and will be equally responsible for the quality and validity results. The main fulfillment of this homework project will be the preparation of a written homework technical report of the design flow and of all the calculations and verifications made. The homework technical report, possibly printed or written in high quality standard, will include the tables with drawings of the system parts. Drawings shall be conforming to current technical standards, either Italian, European, or International. The report shall be delivered before the end of the course period (end of the lectures): failure to comply with this deadline will prevent participation to the exams. Delivery will be fulfilled in electronic form according to specifications that will be detailed during the course. The report will be evaluated and rated for what concern the design and drawing contents: rating is indicated in the following, in the section dedicated to the exams rules. A minimum acceptable quality of both design calculations and drawings is strictly requested. The teachers will evaluate the outcome of the homework project that is reported in the technical report, and can reject it: in this case the exam will not be recorded, even in the case of a positive result, and must be repeated until an acceptable report is presented within the same date of the written exam and rated. 
Texts, readings, handouts and other learning resources
Material used by the teachers during the lectures, and distributed through the university portal.
Notes directly taken from the classes will be shared with students through the website. Electronic resources that can be found in the internet will be also suggested. Main study references: • Budynas, R., Nisbett, J., Shigley’s Mechanical Engineering Design, 8th Edition in SI units, McGraw Hill, 2008 • Juvinall, R.C., Marshek, K.M., Fundamentals of machine component design, 4th Edition, Wiley, 2006 • Childs, P.R.N., Mechanical Design, 2nd Edition, Elsevier, 2004 (also in eBook format, see library website) • Rossetto, M., Introduzione alla fatica dei materiali e dei componenti, Levrotto & Bella, Torino, 2000 • Goglio, L., Resistenza dei Materiali e dei Collegamenti, Levrotto & Bella, Torino, 2006 • Collins, J.A., Failure of Materials in Mechanical Design, 2nd Edition, Wiley, 1993 Additional textbooks: • Suresh, S., Fatigue of materials, Cambridge University Press, 1998 • Niemann, G., Winter, H., Maschinenelemente, 2nd Edition, Springer, 1983 • Niemann, G., Winter, H., Elementi di Macchine, Edizioni di Scienza e Tecnica, 1986 • Niemann, G., Winter, H., Höhn, B., Manuale degli organi delle macchine, Tecniche Nuove, Milano, 2006 • Giovannozzi, R., Costruzione di Macchine, vol. 1 & 2, Patron, 1980 (historical) • Pighini, U., Elementi Costruttivi delle Macchine, Edizioni Scientifiche Associate, 1980 (historical) • Strozzi, R., Lezioni di Costruzione di Macchine, Pitagora, Bologna, 1998 • Riccadonna, A., Todeschini, M., Disegno, progettazione e tecniche di produzione, Hoepli, 2008. • Straneo, Consorti, Disegno, progettazione e organizzazione industriale, Vol. I, II, III, Principato • Moos, S., Vezzetti, E., Tornincasa, S., Zompì, A., Quotatura funzionale degli organi di macchine, CLUT 
Assessment and grading criteria
It is expected that the student achieves specific skills such as:
1. To perform preliminary verification and dimensioning calculations on the main machine components, with the aid of tables, diagrams and formulas from technical codes and standards; 2. To read and understand drawings of assembly of medium complexity and understand how the represented devices work; 3. To use of parametric 3D software (Solidworks) for the generation of parts and assemblies and for the generation of 2D drawing of features of the components; 4. To represent every components with the correct GD&T nomenclature in order to limit geometrical and dimensional imperfections to guarantee a proper operation in service. The final exam consists of two parts referring respectively to the Written exam Part and to the part of CAD drawing (Practical Part  LAIB exam). There is no oral examination, the date for the oral examination is used only to show, upon request of the student, the evaluation of the Written exam paperwork and the CAD drawing Practical Part. In this date students can ask for explanation about the evaluation process of their paperwork. The student can not share comments nor can compare results with other students. This part does not change or contribute to the final score of the exam. Dates and classrooms for the Written exam Part, the CAD drawing Practical Part and the paperwork verification upon request of the student will be indicated in the educational portal. To be admitted to any part of the exam, it is required to have and to show a valid identification card or the personal university card with a clearly readable photograph. In absence of this evidence the candidate will be rejected and the attendance to the test forbidden. The use of any electronic digital device (phones, smartphones, tablets, computers, etc.) except calculators (even programmable, but without any operating system) is strictly forbidden. The use of any of these digital electronic devices will be subjected to cancellation of the test and expulsion from the examination room. Only the material provided by the teachers and their assistants can be used, except for paper, pens and pencils, rubbers and correctors, rulers and other measuring and drawing aids and calculators. The use of any types of written or typed papers, books or handbooks is not admitted and is a reason for immediately excluding the student from the examination. All the material distributed by the teachers and their assistants shall be entirely returned. Failing to return the material will exclude from the examination. It is not permitted to communicate in any form with other students or with any other person except the teachers and their assistants. Any transgression will be subjected to expulsion and exclusion from the exam. Admission to the exams follows registration to the call in the dates indicated in the portal. The student has 15 minutes from the start of any written test to withdraw: after this time the exam will be recorded as failed. Also in the case of withdraw, all the given material shall be entirely returned. • Written Part (duration about 2.5 hours): at the end of all the classes, the student will be required to attend a Written test, divided in three parts: o 3 open questions on general topics of Machine Design where it is requested to describe a topic included in the course by developing the answer in the most concise way using formulas, drawings, diagrams which are pertaining to the question for a complete representation of the answer. Each of the three questions is rated from 0 to 5 for a maximum of 15. o 3 exercises of Machine Design to be numerically solved; exercises will be like the ones solved during practice. Correct numerical results are mandatory: development of the calculations is not sufficient for a positive outcome, as well as erroneous numerical results. Each of the three exercises is rated from 0 to 5 for a maximum of 15. The final score of the written exam for the Machine Design part is obtained by summing up the two scores so that the maximum score is 30. This score is referred to the part of Machine Design and is called A. o 10 questions of CAD Theoretical Part with multiple answers. A maximum of 7.5 points is associated to this part and is called B1. • CAD Practical Part (laboratory test, duration about 2 hours): This part aims at evaluating the student’s operational ability. The test will be as follows: o Inputs given to the student at the beginning of the Practical Part: 1. A 2D assembly drawing of a mechanical system 2. A 2D drawing of one part of the system 3. All the remaining 3D part models of the system 4. The part of the system to be represented on a 2D GD&T drawing o student’s actions during the test:  Understand how the system works  Model the part ‘Input  2’  Assemble all the parts in a working system  Make the 2D GD&T drawing of the ‘Input  4’ o Test Output produced by the student at the end of the Practical test:  3D model of the part ‘Input  2’  3D assembly of the system  2D GD&T drawing of the part ‘Input  4’ Each of the three output is rated from 0 to 7.5 for a maximum final score of 22.5. This score is referred to the part of CAD drawing Practical Part and is called B2. Both tests (Written and Practical Part) must be taken for the same date. In detail, the Winter examination session has two dates to take the exam: it is not possible to take the Written part in the first date and take the CAD Practical Part in the second date. Moreover, it is not possible to take the Written exam in one session (e.g., Winter examination session) and the CAD Practical Part in another session (e.g., Summer examination session). To complete the exam, the student has to pass initially the Machine Design part (A) and CAD Part (B = B1 + B2) with a sufficient score equal or higher than 18, i.e., A>=18 and B>=18. If both tests will be evaluated sufficient, final score will be computed as a weighted average between the marks of the two parts of the exams according to the number of credits associated to the Machine Design part (8 credit) and CAD drawing part (4 credit), plus additional points from the evaluated homework technical project. First of all, the teachers will evaluate the outcome of the homework project that is reported in the technical report, and can reject it if it is considered not acceptable: in this case the exam will not be recorded, even in the case of a positive result, and must be repeated until an acceptable report is resent within the same date of the written exam and rated. A technical report is considered unacceptable if it completely lacks of one of the requested sections. If the technical report is considered acceptable, the range of points assigned to the report goes from 3 to +3. 1 point is subtracted if the team did not report all the diagrams that are requested on the technical report. 1 point is subtracted for the lack of details on each diagram (lack of scale, axes, legends, correct dimensions and units, clarity) presented in the homework technical report. Note that the report shall be delivered before the beginning of the Examination session where the student decided to take exam. Failure to comply with this deadline will prevent participation to the following session exam. Delivery of the technical report will be fulfilled in electronic form according to specifications that will be detailed during the course. THE FINAL SCORE WILL BE DETERMINED AS FOLLOWS: 1) Written test  Machine Design Questions (3) = max 15/30  Machine Design Exercises (3) = max 15/30 Total Machine Design score in the Written test (Machine Design Questions + Exercises) = max 30/30 (= A)  CAD Theoretical questions (10) = max 7.5/30 (= B1) 2) Practical test  CAD = max 22.5/30 (= B2) 3) Technical report and drawings = max 3 points (= C) Final score = ( (2/3)*A+(1/3)*(B1+B2) ) + C 
