Manufacturing Technology (ME461) Lecture15

Manufacturing Technology (ME461)

Instructor: Shantanu Bhattacharya

Review of previous lectures

• Basics of NC program • Modal and Non modal commands • Absolute and incremental positioning. • Types of block formats (Fixed sequential method, tab

sequential format, word format) • Word address format • Preparatory functions, axis motion commands, Feed

and speed commands, Identification commands and Miscellaneous commands.

• G-code, Canned cycles • Special characters.

Example of NC code Write an NC program to machine a ½ in. wide L-shaped slot in a mild steel workpiece with dimensions 3X2.5X0.75 in as shown in Figure:

Assumptions: 1. The top lower left corner will be used for program zero. 2. Machining motion will start in the indicated position. 3. The tool is ¼ in. above the top surface of the part prior to start of machining. 4. The tool diameter used is ½ in., so only one pass is required. 5. A cutting speed of 500 rpm and feed rate of 10in./ min are used for machining. 6. Machine specification: N3G2X + 43Y + 43Z+ 43R+ 43F4S4T2M2

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Example of NC Code

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Example problem of NC Code

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Example problem of NC code

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Content of the MID SEM EXAM

•Theoritical Portion will have a 20% weightage and Numerical portion will have a 80% weightage. •The paper will contain both short answer questions and long questions. •The total duration is 1 hr. and the total full marks are 45. •The scores would be treated out of 15. Only 1/3rd of the marks obtained will count towards your final score. •Please refer to the assignment# 1 well before coming for the examination.

Topics to be covered (Computer Aided Design, CAD)

1. The Product Design Process

• Problem identification, Preliminary ideas, refinement process, analysis process, decision process, Implementation process

2. Computer Aided Design

3. A brief history of CAD

4. CAD/CAM system

• Mainframe based systems, Minicomputer based systems, Workstation based systems, Microcomputer based systems

5. CAD system Input-Output Devices

6. Selection of CAD/ CAM systems

7. Computer graphics and transformations

• Geometric transformation, homogeneous representation, Composition of transformations

Topics to be covered (Geometric Modeling)

1. Introduction to geometric modeling.

2. Why is knowledge of geometric Modeling Necessary?

3. Geometric Modeling Approaches

4. Wireframe Modeling

• Limitations of wireframe modeling, Wireframe Entities, Analytic curves, Representation of curves, Nonparametric representation of curves, Parametric representation of curves, Synthetic curves, Parametric representation of Synthetic curves, Hermite cubic spline, Bezier curves, B-Spline, Rotational B-Spline and non uniform rotational B-Spline curves, Curve manipulations.

5. Surface modeling

• Surface entities, surface representations

Topics to be covered (Computer Aided Process Planning)

1. Overview of manufacturing processes

• Turning Operations, Drilling Operations, Milling Operations, Grinding Operations

2. What is Process Planning?

3. Basic steps in developing a Process Plan

• Analysis of part requirements, Selection of Raw work-piece, Determining manufacturing operations and their sequences, selection of machine tools, Selection of tools, work-holding devices, inspection equipments etc., determining machining conditions and manufacturing times.

4. The principle process planning approaches

• Manual experience based planning methods, computer aided process planning method.

5. Variant and generative process planning systems.

6. Feature recognition in computer aided process planning