Computer Numerical Control

Code:

EM0045

Acronym:

CNC

Keywords
Classification	Keyword
OFICIAL	Automation

Instance: 2011/2012 - 1S

Active?	Yes
Responsible unit:	Automation, Instrumentation and Control Section
Course/CS Responsible:	Master in Mechanical Engineering

Cycles of Study/Courses

Acronym	No. of Students	Study Plan	Curricular Years	Credits UCN	Credits ECTS	Contact hours	Total Time
MIEM	18	Syllabus since 2006/2007	5	-	6	56	160

Teaching language

Suitable for English-speaking students

Objectives

Background:
The CNC technology is a fundamental technology of the modern factories mainly in the manufacturing industry. So it is essential for a mechanical engineer specialized in the automation area to be familiar with this technology, its potential, its applications and how to programme and operate it. This unit aims to prepare the students to be able to recognize the suitability of applying the CNC technology to specific industrial processes as well as to prepare them to design and implement CNC based control systems.

Specific Aims:
To provide the students with the necessary tools so they can be able to understand, design and implement flexible manufacturing equipments based on CNC technology, integrate CNC technology with other production systems as well as with Computer Aided Design and Computer Aided Manufacturing Systems.

Previous knowledge:
Technical Design for mechanical engineering – Mechanical technical design.
Systems dynamics – Automatic control.
Design of mechanical structures – Structures design and dimensioning.
Computer Aided Design and Computer Aided Manufacturing – Computer Aided Design and Manufacturing.
Sensors, transducers and instrumentation – Electricity and instrumentation.
Programmable Logic Controllers - Industrial computing.

Percentual Distribution:
Scientific component (establishes and develops scientific bases) – 40%
Technological component (apply to design and process operation) - 70%

Learning outcomes:
Knowledge and Understanding – recognize the specific attributes of the CNC technology and in what conditions and requirements it is suitable as a computerized control systems.
Engineering Analysis – Analysis and formal specification of the requirements of any practical application of a CNC system.
Engineering Design – Design of the mechanical systems as well as of the CNC solution for a particular situation in which this type of technology is the most suitable.
Investigations – Seek for the most suitable components and solutions available in the market for building a tailor made mechanical and control system.
Engineering Practice – Implement CNC based control systems.

Program

CHAPTER 0: Introduction to Computer Numerical Control.
Fundamentals and main attributes of CNC technology. CNC technology as a building block of FMS-Flexible Manufacturing Systems. CNC and types of automation: programmable, flexible and dedicated. CNC and conventional, manual operated, machines.

CHAPTER 1:Flexibility in production systems.
Flexibility concepts and limitations of FMS-Flexible Manufacturing Systems. Modern manufacturing systems and concepts: Computer Integrated Manufacturing (CIM), Just in Time (JIT) and Lean Production, Agile Manufacturing and Virtual Manufacturing.

CHAPTER 2: Applications of CNC technology.
Conventional and nonconventional machining processes (EDM, Laser cutting), sheet metal cutting, inspection stations and coordinate measuring machines, material handling, components assembling.

CHAPTER 3: Computer Numerical Control: detailed analysis
Architecture of the CNC; building blocks; functional blocks; interface level; processing level; process control level; axis control. Numerical control types: point to point, linear control, contouring. Adaptive machining control: adaptive control with optimization (ACO) and adaptive control by constraints (ACC). Generation of tool trajectory: reference systems; resolution; systematic and variable errors; Errors compensation. Tolerance of trajectory.

CHAPTER 4: Design of equipments controlled by CNC
Structural components: base elements, movements, automatic tool change, fixing and automatic part load/unload systems, axis designation and references. Tool monitoring and management systems.

CHAPTER 5: Numerical Control Programming
Alternative methods for NC programming: basic structure of the ISO programming languages for NC. Computer assisted NC programming: APT programming language, graphical programming and CAD/CAM systems, post-processors. CAD/CAM integration and STEP(Standard for the exchange of product model data): ISO 10303, AP 203, AP24, AP238 (STEP-NC). Computer Aided Process Planning (CAPP) and CAD/CAM integration.

CHAPTER 6: Integration of CNC equipment
Integration of CNC with other systems at the information exchange level control level. Integration of the flow of information and at the control levels: direct and distributed numerical control (DNC).

CHAPTER 7: Selection of CNC equipments
Criteria for assessment and comparison of CNC equipments: control attributes, CNC controller and mechanical system.

CHAPTER 8
Performance evaluation, methods and systems for testing the CNC equipments geometry. Permanent errors and compensation curves.

Mandatory literature

Suh, Suk-Hwan 070; Theory and design of CNC systems. ISBN: 978-1-84800-335-4
Altintas, Yusuf; Manufacturing automation. ISBN: 978-0-521-65973-4

Complementary Bibliography

HMT Limited; Mechatronics and machine tools. ISBN: 0-07-134634-1
Thyer, G. E.; Computer numerical control of machine tools. ISBN: 0-7506-0119-1
Groover, Mikell P.; Automation, production systems, and computer-integrated manufacturing. ISBN: 0-13-088978-4

Teaching methods and learning activities

Room classes to expose and discuss concepts and technology associated with CNC.
Elaboration of solutions for case studies concerning practical applications of CNC technology.
Laboratory classes to practice the use, parameterization and set up of CNC and CAM systems. Demonstration of existing CNC equipments for conventional and non-conventional machining.

keywords

Technological sciences > Engineering > Control engineering > Automation

Evaluation Type

Distributed evaluation with final exam

Assessment Components

Description	Type	Time (hours)	Weight (%)	End date
Attendance (estimated)	Participação presencial	56,00
	Total:	-	0,00

Eligibility for exams

75% of presences registered on the taught classes.

Calculation formula of final grade

- 60% final written exam
- 40% continuous evaluation based on the results of the case studies.

Examinations or Special Assignments

Propose solutions for three case studies.

Special assessment (TE, DA, ...)

Written exam.

Classification improvement

This will be done accordingly to the General Evaluation Rules of FEUP.