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Transcript of 67049-Ch16
©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book
Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover. 1/30
Ch 16 Automated Production Lines
Sections:
1. Fundamentals of Automated Production Lines
2. Applications of Automated Production Lines
3. Analysis of Transfer Lines
©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book
Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover. 2/30
Automated Production Lines
High production of parts requiring multiple processing operations
Fixed automation Applications:
Transfer lines used for machining Robotic spot welding lines in automotive final
assembly Sheet metal stamping Electroplating of metals
©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book
Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover. 3/30
Where to Use Automated Production Lines
High product demand Requires large production quantities
Stable product design Difficult to change the sequence and content of
processing operations once the line is built Long product life
At least several years Multiple operations required on product
Different operations are assigned to different workstations in the line
©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book
Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover. 4/30
Benefits of Automated Production Lines
Low direct labor content Low product cost High production rates Production lead time and work-in-process are minimized Factory floor space is minimized
©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book
Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover. 5/30
Automated Production Line
“Fixed-routing manufacturing system that consists of multiple workstations linked together by a material handling system to transfer parts from one station to the next”
Slowest workstation sets the pace of the line (bottleneck) Workpart transfer:
Palletized transfer line Uses pallet fixtures to hold and move work parts
between stations Free transfer line
Part geometry allows transfer without pallet fixtures
©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book
Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover. 6/30
Automated Production Line
General configuration of an automated production line consisting of n automated workstations that perform processing operations
©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book
Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover. 7/30
System Configurations
In-line - straight line arrangement of workstations
Common for machining big workpieces, since they require large number of operations.
Segmented in-line – two or more straight line segments, usually perpendicular to each other
Used because of unavailable workspace, need for reorientation of the workpiece or need for returning the fixtures to the front of the line.
Rotary indexing machine (e.g., dial indexing machine)
Limited to smaller parts and fewer workstations.
©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book
Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover. 8/30
Segmented In-Line Configurations
L-shaped layout
U-shaped layout
Rectangular configuration
©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book
Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover. 9/30
Two Machining Transfer Lines
©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book
Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover. 10/30
Rotary Indexing Machine
©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book
Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover. 11/30
Workpart Transfer Mechanisms
Linear transfer systems: Continuous motion – not common for automated
systems Synchronous motion – intermittent motion, all
parts move simultaneously Asynchronous motion – intermittent motion, parts
move independently Rotary indexing mechanisms:
Geneva mechanism Others
©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book
Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover. 12/30
Belt-Driven Linear Transfer System
Side view of chain or steel belt-driven conveyor (over and under type) for linear transfer using work carriers
©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book
Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover. 13/30
Walking Beam Transfer System
©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book
Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover. 14/30
Geneva Mechanism with Six Slots
©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book
Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover. 15/30
Cam Mechanism to Drive Dial Indexing Table
©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book
Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover. 16/30
Storage Buffers in Production Lines
“A location in the sequence of workstations where parts can be collected and temporarily stored before proceeding to subsequent downstream stations”
Reasons for using storage buffers: To reduce effect of station breakdowns To provide a bank of parts to supply the line To provide a place to put the output of the line To allow curing time or other required delay To smooth cycle time variations To store parts between stages with different production rates
©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book
Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover. 17/30
Storage Buffer
Storage buffer between two stages of a production line
©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book
Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover. 18/30
Control Functions in an Automated Production Line
Sequence control To coordinate the sequence of actions of the transfer
system and workstations Safety monitoring
To avoid hazardous operation for workers and equipment
Quality control To detect and possibly reject defective work units
produced on the line
©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book
Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover. 19/30
Applications of Automated Production Lines
Transfer lines for machining (Figure) Synchronous or asynchronous workpart transport Transport with or without pallet fixtures, depending on
part geometry Various monitoring and control features available
Rotary transfer machines for machining Variations include center column machine and trunnion
machine
©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book
Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover. 20/30
Rotary Transfer Machine (Plan View)
©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book
Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover. 21/30
Center Column Machine (Plan View )
©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book
Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover. 22/30
System Design Considerations
Building block approach: machine tool companies specialize in transfer lines and indexing machines User contracts for custom-engineered line Standard modules such as workheads, feed units,
transfer mechanisms, and bases Called a unitized production line
Link line: uses standard machine tools connected by specialized handling system
Specialized processes often engineered by the user company
©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book
Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover. 23/30
Standard Feed Units used with In-Line or Rotary Transfer Machines
(a) Horizontal feed drive unit, (b) angular feed drive unit, and (c) vertical column feed drive unit
©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book
Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover. 24/30
Standard Milling Head
Milling head unit that attaches to one of the feed drive units in the previous slide
©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book
Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover. 25/30
Analysis of Transfer Lines
Three problem areas must be considered:
1. Line balancing To divide the total work load among workstations
as evenly as possible
2. Processing technology Theory and principles about the manufacturing or
assembly processes used on the line
3. System reliability - two cases: Transfer lines with no internal parts storage Transfer lines with internal storage buffers
©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book
Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover. 26/30
Lines with No Internal Storage Buffers
Figure
Assumptions: The workstations perform processing operations, not
assembly Processing times at each station are constant, though not
necessarily equal Workpart transport is synchronous There are no internal storage buffers
©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book
Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover. 27/30
What the Equations Tell Us – Lines with No Storage Buffers
As the number of workstations increases Line efficiency and production rate are adversely
affected As reliability of individual workstations decreases
Line efficiency and production rate are adversely affected
©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book
Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover. 28/30
Lines with Internal Storage Buffers
Downtime on an automated line due to starving and blocking can be reduced by adding one or more parts storage buffers between workstations.
Starving on an automated line means that a workstation is prevented from performing its cycle because it has no part to work on.
Blocking means that a station is prevented from performing its work cycle because it cannot pass the part just completed to the neighboring downstream station.
For an n-stage line, there will be n-1 or less storage buffers, not including the raw parts inventory or the finished parts inventory.
©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book
Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover. 29/30
What the Equations Tell Us – Lines with Storage Buffers
If E0 and E are nearly equal
Then little advantage is gained by adding a storage buffer
If E is much greater than E0
Then adding a storage buffer may improve line performance significantly
Storage buffers should be located so that production rates of the stages are about equal
During operation, if any buffers are always empty or always full, then the buffer is serving little purpose
©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book
Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover. 30/30
What the Equations Tell Us - Lines with Storage Buffers
The maximum possible efficiency is achieved by: Setting the number of stages = number of stations Using large buffer capacities
The “law of diminishing returns” operates in multi-stage automated lines: As the number of storage buffers is increased, line
efficiency improves at an ever-decreasing rate As storage buffer capacity is increased, line efficiency
improves at an ever-decreasing rate