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1
ISE 484/ME 473 Flexible and Lean Manufacturing Systems
Course Outline
R. Van Til Industrial & Systems Engineering Dept.
Oakland University
Copyright 2012. Robert P. Van Til. All rights reserved.
2
Focus of Course
• Technologies which increase flexibility in the modern manufacturing environment will be considered.
Ø Either in small batch systems or in large mass production systems.
Ø The emphasis will be on: What are the technologies?
How do you use them?
3
Focus of Course
• For example, a Computer-Aided Manufacturing (CAM) system. Ø We will study:
What is a CAM system.
How to operate a CAM system.
How to use CAM as a bridge from CAD to CNC.
Ø We will not study: How a CAM system makes all those pretty pictures.
• That is, linear transformation theory, splines, and a whole lot of other mathematical techniques that take place inside a CAM program.
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Course Topics
• Overview of the manufacturing environment. • Manufacturing safety procedures. • Performance of production systems. • Lean manufacturing. • Group Technology (GT). • Robotic systems. • Material transport & storage systems. • Programmable Logic Controllers (PLC). • Vision systems. • Sensors. • Geometric dimensioning & tolerancing. • Computer Numerically Controlled (CNC) systems. • Computer-Aided Manufacturing (CAM).
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Manufacturing Overview
• Broad overview of the modern manufacturing environment.
Ø Classification of manufacturing systems.
Ø Manufacturing’s essential functions.
Ø Production planning.
Ø Manufacturing plant layout.
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• Parts flow through a production system to produced finished products. Ø We will consider the behavior of flow lines.
Many different products are produced in flow lines. • Cars, airplanes, consumer electronics and cookies
Number of products produced (throughput) and distribution of parts in the flow line (Work-In-Progress or WIP) effected by:
• Machines with different processing times.
• Machine failures.
• Accumulator locations and capacities.
Performance of Production Systems
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Lean Manufacturing
• Lean manufacturing is based on the Toyota Production System.
Ø Major focus of lean manufacturing is on the reduction of waste throughout the system.
Several lean manufacturing tools will be presented.
Ø Lean techniques are also being applied in many nonmanufacturing industries. Examples: healthcare, service and logistics.
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Group Technology
• Group technology (GT) involves the classification of different parts that have similar:
Ø Design attributes.
Ø Manufacturing attributes.
• Hence, when it’s time to design or manufacture a new part, use the GT classification code to find how similar parts were designed or manufactured.
• GT is used to answer that age-old question:
Why reinvent the wheel?
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Robotic Systems
• Robots are programmable devices which are primarily used to:
Ø Transport material. Example: Load/unload machine tools
Ø Process parts. Examples: Spot welding or spray painting
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• Material transport systems.
Ø Conveyors
Ø Fork Lifts
Ø Automated Guided Vehicles (AGV)
• Material storage systems.
Ø Warehouse
Ø Accumulating conveyors
Ø Automated Storage/Retrieval Systems (AS/RS)
Material Transport & Storage
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• Material transport and storage are nonvalue-added processes.
Ø Hence, it is very important to optimize them. One goal of lean manufacturing is to minimize the
amount of material transportation and storage.
Material Transport & Storage
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• A PLC is a microprocessor device used to control manufacturing systems.
Ø Often used to control sequential processes. Examples. A conveyor system or a multi-robot spot
welding station.
Ø PLC programming methods:
Ladder logic diagrams (older method).
Sequential function charts, flow charts (newer methods).
Programmable Logic Controller (PLC)
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Initial
Load_part
Press_dwn
Press_up
Unload_part
I1_Run
O1_Prox
O2_LS_Dwn
O3_LS_Up
NOT O1_Prox
Example - PLC Sequential Function Chart
N O6_Press_ram
N O4_Conv1_Mtr
N O5_Conv2_Mtr
N O7_Robot
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Vision Systems
• A vision system collects data for use by the manufacturing system.
Ø Usually illuminate objects with either visual light or laser light.
Ø Vision systems are used for: Feature identification.
• Example: Tell a robot where a car’s windshield frame is located so it can place the windshield.
Inspection.
• Example: Did the machine tool cut a correct size hole in the specified location?
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Sensors
• A sensor measures some physical quantity and converts it to an electrical or visual signal.
Ø Electrical signals often send to computers.
Ø Visual signals often send to humans.
Ø Example: Sensor that measures your car’s speed. Electrical: sent to car’s cruise controller in order to
control the speed.
Visual: a gage (i.e., speedometer) displays the speed to the driver.
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Sensors
• In manufacturing, sensors often used by computers and humans to monitor and control various systems.
Ø Types of sensors used in manufacturing:
Thermal
Mechanical
Electrical
Optical
Chemical
Acoustic
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• An international standard used for placing dimensions and tolerances on engineering drawings.
Ø Standard implies that everyone uses the same:
Definitions
Terminology
Symbols
Geometric Dimensioning & Tolerancing
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• A computer-based control system used to control various manufacturing systems.
Ø Usually used to control machine tools such as lathes, mills, machining centers and grinders.
Ø Uses a low-level programming language. Commands called G-codes.
Computer Numerical Control (CNC)
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N5 G90 G20 N10 M06 T2
N15 M03 S1200 N20 G00 X1.00 Y2.20 Z-3.75
N25 G01 X-0.50 Y1.25 F5.0 N30 G01 X0.25 Y-0.55 F3.5
N35 G00 Z0.00 N40 G00 X0.00 Y0.00 Z0.00 N45 M05
N50 M30
Example - G-Code Program
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• A CAM system converts a CAD diagram of a part into a CNC G-code program to produce the part. Ø A high-level programming language.
Ø CAM is a 2 step process: 1. Using the CAD drawing, guide a simulated CNC
machine tool through the desired machining process.
» Called a tool path diagram.
2. Convert the tool path information into a G-code program.
» Called post-processing.
Computer-Aided Manufacturing (CAM)