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Manufacturing Processes(IM 212)

Department of Industrial & Management Engineering

College of Engineering and Technology

Lecture 1 : Introduction to Manufacturing Processes

Arab Academy for Science, Technology,and Maritime Transport

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https://sites.google.com/site/academyind/home

Course Contents

1. Introduction to Manufacturing Processes

2. Mechanics of Chip Formation

3. Cutting Tools for Machining

4. Tool Wear and Tool Life

5. Economics of Machining

6. Turning

7. Drilling and Reaming

8. Milling

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9. Broaching and Shaping

10. Grinding

11. Finishing Operations

12. Numerical Control of Machine Tools

13. Nontraditional Machining

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Course Assessment

7th Week Examination : 30 (20 + 10)

12th Week Examination: 20 (10 + 10)

Weeks 1-15 : 10

Final Examination : 40

Total Marks : 100

•Reference:

Fundamentals of Machining Processes: Conventional and Nonconventional Processes

Author: Hassan El-Hofy, Alexandria University, Egypt

Publisher: CRC – Taylor and Francis, Boca Raton, Florida, USA

Cat. #: 7288

ISBN: 0849372887

Publication Date: 25 . 08 . 2006

Number of Pages: 4883

Course Objectives

At the end of this course, student should be aware of the following:

1. Classification of the machining technologies.

2. The material removal mechanism of each process.

3. Machining system components.

4. Economics of machining.

5. Effect of the different variables on the process behavior.

6. Selection of the proper machining process for any application.

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Overview of Manufacturing Processes

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• Manufacturing is the process of converting raw materials into products.

• Manufacturing represents 20-30% of the value of all goods and services produced inindustrialized countries.

• Machining activities constitute ~ 20% of the manufacturing activities in the USA.

Classification of Manufacturing Processes

Classification of Machining Processes

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Machining: is the removal of the unwanted material (Machining Allowance) from theworkpiece in order to obtain a finished product of the desired size, shape,and surface quality.

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Classification of Machining Processes

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• Cutting: machining allowance is removed in the form of visible chips.

• Abrasion: machining allowance is removed in the form of minute and invisiblechips by hard, tiny, and randomly oriented abrasive grit (bonded or loose) ofindefinite number and shape.

• Erosion: machining allowance is removed in the form of successive surface layersas a result of dissolution, melting and vaporization of the material being machined.

Cutting Abrasion

Machining by Cutting

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• The tool is penetrated into the workpiece by a depth of cut.

• Cutting tools have definite number of cutting edges of a known geometry.

• The machining allowance is removed in the form of visible chips.

• The shape of the workpiece produced depends on the tool-workpiece relative motion.

Workpiece

Cutting SpeedDepth of Cut

Cut Surface

Chip

Tool

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WorkpieceTool

Stationary Linear Rotary Spiral

StationaryShaping

BroachingDrilling

Linear Planing Milling

Rotary Turning

Spiral Hobbing

Tool and Workpiece Motions

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Classification of Cutting Processes

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Based on Number of Cutting Points/Edges

Machining by Cutting

Single Point Multi point

TurningBoring

ShapingPlaning

DrillingReaming

MillingBroaching

HobbingSawingFiling

Machining by Cutting

Form Generation Form & Generation

ShapingPlaningDrilling

Form TurningForm Milling

TurningShapingPlaning

Pocket MillingContour Milling

Thread CuttingSlot Milling

Gear Hobbing

Based on Cutting Kinematics

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Classification of Cutting Processes

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Generation Cutting Form-Generation Cutting

General Aspects of Machining Technology

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General Aspects of Machining Technology

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Main Elements of Machining by Cutting

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Main Elements of Machining by Cutting

• During metal cutting three different types of chip are formed that affects theproduct accuracy and surface roughness.

• The type of chip formed depends on the workpiece material and the machiningconditions.

Discontinuous (Segmented) Chip

Chip Formation

Continuous Chip Continuous Chip with Built-Up Edge (BUE)

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Workpiece

Chip

Tool

Cutting Speed

Discontinuous (Segmented) Chip• Discontinuous chips are produced when brittle materials such as Cast Iron and

Bronze are cut.• As the cutting tool contacts the metal, some compression stresses occur, and

the chip begins to flow along the chip-tool interface.• The metal compresses until rupture which occurs at the shear plane and the

chip separates from the workpiece.

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Discontinuous (Segmented) Chip• This type of chip causes:

• Variations of the cutting forces that result in vibrations.

• Loss of product accuracy.

• Poor surface quality.

• Extensive tool wear.

• Machining conditions producing this type of chip:

1. Materials that contains hard inclusions and impurities.

2. Very low/very high cutting speeds.

3. Large depth of cuts.

4. Very small or -ve rake angles.

5. Low stiffness of the machine tool.

6. Lake of the effective cutting fluid.

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Continuous Chip• Fractures or ruptures do not occur because of the ductile nature of the metal.• Although continuous chip is considered an ideal for better surface finish, low

power consumption and longer tool life, they are not always desirable as they tendto tangle around the tool holder.

• Hence, machining operation has to be stopped to clear away the chips.• Chip breakers are therefore used to break chips but they increase cutting tool

cost and raise cutting forces and power.

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Tool

Chip

Workpiece

Cutting Speed

• Machining conditions producing this type of chip:

1. Ductile/soft materials (Mild Steel, Copper, and Aluminum).

2. High cutting speeds (>60 m/min).

3. Small depth of cut.

4. Small feed rate.

5. Sharp cutting edge.

6. Tool material of low coefficient of friction.

7. Efficient cutting fluid.

8. Large (+ve) rake angles.

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Continuous Chip

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• Chip breakers are used to split the chips.

• The use of chip breakers increases cutting tool cost and raises cutting forcesand power.

• Types of chip breakers:

1. Groove Type.

Chip BreakerLand Width

Chip Breaker Depth

Chip Breakers

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Chip BreakerHeight

Chip Breaker Wedge Angle

Chip Breaker Distance

a) Attached

Chip Breaker Distance

b) Integrated

Chip BreakerHeight

Chip Breakers

2. Obstruction Type:

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Continuous Chip with Built-Up Edge (BUE)

BUE

BUE Welded to Machined Surface

BUE Fragments Welded to Chips

Cutting Speed

• The local high temperature, the high pressure and the frictional resistance to theflow of the chip cause the work material to adhere to the cutting edge of the toolforming the Built-Up Edge (BUE).

• The rest of the material randomly adheres to the workpiece cut surface resulting in:• Poor surface finish.• Changes the geometry of the cutting tool.• Causes failure of the cutting tool.

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• Machining conditions producing this type of chip:1. Ductile materials such as Mild Steel, Copper, and Aluminum.2. Low cutting speed (<60 m/min).3. Large depth of cut.4. Large feed rate.5. Dull (not sharp) cutting edge.6. High friction at the chip-tool interface.7. Insufficient cutting fluid.8. Small (+ve) rake angles.

Continuous Chip with Built-Up Edge (BUE)

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Factors Affecting Cutting Processes

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