Learning objectives
This course aims at teaching the fundamental knowledge for studying the functional and constructive features of mechanical devices, by means of drafted representations that comply with technical standards, and according to their choice as a consequence of the production process.
The course goal is to provide to students adequate awareness and knowledge to develop and understand technical drawings both for single parts and for assemblies. In particular, the learning of the following basic skills are required:
(i) to understand theory and basic notions on technical drawing and its related standards
(ii) to know the main elements and modules of machines and mechanical systems
(iii) to draft technical drawings based on their application and the manufacturing processes needed to realize the parts
(iv) to compare design alternatives for mechanical systems based on external requirements
(v) to develop adequate independence in the evaluation of mechanical systems for a correct design and representation
(vi) to develop a fluency in the representation of mechanical systems (both in hand-sketching and with the help of software tools)
(vii) to be able to provide new concepts and design solutions for components and assemblies considering the changing of external requirements
(viii) to know the modelling strategies to be used in the CAD software (computer-aided-design)
Prerequisites
None
Course unit content
At the beginning of the course there is an introduction about the basics of technical drafting, such as geometric constructions, orthogonal projections, axonometries, representations of surfaces, sections, rotations and reflections.
After some forewords about science of materials, metrology, machining, this course thoroughly deals with typical issues of mechanical drafting, considering most used standards, conventional representations, and most common principles of dimensioning. Relationships with production and control processes are carefully taken into consideration.
Further topics are dimensional tolerances, geometric tolerances and surface roughness.
There is a thorough analysis of separable joints (by means of threaded parts), fixed joints (welding, soldering) and elastic connections (by means of springs). Furthermore, couplings used for torque transmission from shaft to other elements are analyzed (keys, cotter, splined shaft, pins).
Other topics are bearings and seals, along with several application examples, with special emphasis on the methodology which lead to their choice and mounting.
The course deals also with mechanical transmission devices, such as shafts, joints, belts, chains and gears.
Solid 3D modelling using CAD (computer aided design) tools is introduced to represent machine components (3D and 2D).
Full programme
1) Machine drawing basis: standards and standardisation authorities, standard sizes of drawing sheets, basic line types and interpretation, font heights and types, drawing scales, sheet layout and title block, drawing types (assembly and part), bill-of-materials.
2) Axonometric projection: classification. Isometric, Dimetric and Cabinet projections.
3) Isometric views: European system (first angle projection), American system (third angle projection). Symbols. Selection of Views. Designation and Relative Positions of Views. Development of Missing Views. Conventional representation.
4) Sectional views: definition, Conventional representation, Position of sectional views. Sectional view types: Full Section, Half Section, Local Section. Hatching of sections.
5) Dimensioning: definitions (dimension line, projection line, termination, value of the dimension). Special indications (Diameters, Chords, Archs, Angles, Radii, Chamfers, Tapered, etc.). Arrangement of dimensions (chain dimensioning, parallel dimensioning, combined dimensioning, co-ordinate dimensioning). Functional dimensioning, Technological dimensioning. Examples.
6) Materials and technologies: chipping, grinding, milling, refining, etc. Introduction to “Geometrical Product Specifications” (GPS).
7) Limits, Dimensional tolerances and fits: Fundamental tolerances, Fundamental deviations, Method of placing limit dimensioning, Standards followed in industry (ISO), Fits (clearance, transition, interference). Indicating Dimensional tolerances on the drawings. Examples.
8) Geometrical tolerances: definitions. Tolerances of Form and Position. Indication of feature controlled. Indicating geometrical tolerances on the drawings. Examples.
9) Surface roughness: Introduction and definition. Surface roughness parameters. Indicating surface roughness on the drawings.
10) Screw thread and Screwed fasteners: Introduction and nomenclature, ISO thread series, Representation of threads. Bolted joints, Locking arrangements for nuts, Foundation bolts.
11) Shaft couplings: keys, Cotters, Pins and Splined shafts.
12) Welded Joints, Riveted Joints, Representation on drawings.
13) Bearings and seals: Introduction and classification, Sliding contact bearings, Rolling contact bearings, Seals (o-ring, v-ring, rotary shaft seal, etc.).
14) Computer-Aided-Design introduction: basic info for solid modelling.
Bibliography
G. Manfè, R. Pozza, G. Scarato. “Disegno meccanico”, Vol. 1, 2, 3, Principato Editore, Milano.
E. Chirone, S. Tornincasa. "Disegno tecnico industriale", Vol. 1 e 2, Il capitello.
UNI M1. “Norme per il disegno tecnico”, Vol.1.
Additionally, all the material used and showed during lectures (slides and workbook), will be available for students after each lecture. This material will be downloadable by Elly web platform or by sending an e-mail to the teacher.
Teaching methods
72 hours of lessons in classroom (9 CFU - 8 hours of lessons for each CFU). 50% of lessons hours will be typical classroom lectures and 50% will be dedicated to classroom exercises (drawings). In case the given time to complete the classroom assignment is not enough for the student, it is required to complete the assignment at home. Drawings produced during classroom exercises are part of the final exam and they must be provided to the teacher during the exam.
Assessment methods and criteria
The exam consists of:
(i) written part (drawing) - 2.5 hours maximum
(ii) oral examination (2-3 questions about the course topics) - 45 minute maximum
Admittance to the oral examination happens only if the written test has been successfully passed. Students' admittance to the oral examination will be communicated through the Esse3 web portal within 3 days from the written test. Final exam evaluation (mark) will be calculated by the teacher considering that the written part has a bigger weight (70%) than the oral examination (30%). Final results will be uploaded to the Esse3 web portal within one week form the oral examination.
Students that did not pass the written part can see the errors after an agreement with the teacher.
Other information
