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 students with the necessary awareness and knowledge to create and interpret technical drawings for both individual parts and assemblies. Specifically, students are expected to acquire the following fundamental skills::
(i) to understand the theory and basic notions of 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 external requirements
Prerequisites
None
Course unit content
At the beginning of the course, there is an introduction to the basics of technical drafting, such as geometric constructions, orthogonal projections, axonometries, representations of surfaces, sections, rotations, and reflections.
After some forewords about materials used in mechanical applications, metrology, and 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 the 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.
Full programme
1) Machine drawing basis: standards and standardization 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) Bearings and seals: Introduction and classification, Sliding contact bearings, Rolling contact bearings, Seals (o-ring, v-ring, rotary shaft seal, etc.).
13) Welded Joints, Riveted Joints, and Representation on drawings.
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 shown during lectures (slides and workbook), will be available for students after each lecture. This material will be downloadable by the Elly web platform or by sending an e-mail to the teacher.
Teaching methods
48 hours of classroom lessons (6 CFU - 8 hours of lessons for each CFU). 50% of lesson 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 a writing assignment which lasts up to 3hours. The exam is characterized by 3 requests:
(i) a technical drawing of an assembly
(ii) a technical drawing of a component
(iii) a set of 3 technical questions related to the topics investigated during the course
The exam is conducted sequentially. The first part (2 hours and 30 minutes) is dedicated to completing the overall assembly drawing and the detailed drawing, while the second part (30 minutes) is dedicated to solving the 3 technical questions.
The exam result (grade) is calculated by the teacher, considering that the drawing part (overall assembly drawing + detailed drawing) has a greater weight (70%) compared to the second part with the technical questions (30%).
If the student wishes to take an oral exam (typically consisting of 2-3 questions related to the course topics), they can request it by emailing the teacher. The oral exam can result in an increase or decrease in the grade obtained from the written exam (and may also result in the student being failed). Access to the oral exam is granted only after passing the written test.
The student must apply to the exam session by registering through the ESSE3 portal (open until 3 days before the scheduled exam date).
The exam results are published on the ESSE3 portal within a week of the exam date.
Students who did not pass the graphic drawing test can review their exam by scheduling an appointment with the teacher.
Other information
None
