Ch36 quality

Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Chapter 36Quality Assurance, Testing, and Inspection

Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Life Expectancy of Some Products

Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Deming’s 14 Points

Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Example of Robust Design

Figure 36.1 A simple example of robust design. (a) Location of two mounting holes ona sheet-metal bracket where the deviation keeping the top surface of the bracket frombeing perfectly horizontal is ±α. (b) New location of holes where the deviation (keepingthe top surface of the bracket from being perfectly horizontal) is reduced to ±α/2.

Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Taguchi Loss Function in Television Sets

Figure 36.2 (a) Objective-function value distribution of color density for televisionsets. (b) Taguchi loss function showing the average replacement cost per unit tocorrect quality problems. Source: Courtesy of G. Taguchi.

!

Loss cost = k Y "T( )2

+# 2[ ]k =

Replacement cost

LSL -T( )2

Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Frequency Distributions

Figure 36.3 (a) A histogram ofthe number of shafts measuredand their respective diameters.This type of curve is called afrequency distribution. (b) Anormal distribution curveindicating areas within eachrange of standard deviation.Note: The greater the range, thehigher is the percentage of partsthat fall within it.

!

Arithmetic mean, x =x1 + x2 + x3 +K+ xn( )

n

Standard deviation, " =x1 # x ( )

2+ x2 # x ( )

2+K+ xn # x ( )

2

n#1

Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Frequency Distribution Curve

Figure 36.4 Frequency distribution curve showing lower and upper limits.

Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

StatisticalQuality Control

Charts

Figure 36.5 Control chartsused in statistical qualitycontrol. The processshown is in good statisticalcontrol because all pointsfall within the lower andupper control limits. In thisillustration, the ample sizeis 5, and the number ofsamples is 1.5.

Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Constants for Control Charts

!

UCL x = x + 3" = x + A2R

LCL x = x # 3" = x # A2R

UCLR = D4R

LCLR = D3R

Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Control Charts

Figure 36.6 Control charts. (a) Processnegins to become out of control because ofsuch factors as tool wear (drift). The tool ischanged and the process is then in statisticalcontrol. (b) Process parameters are not setproperly; thus, all parts are around the uppercontrol limit (shift in mean). (c) Processbecomes out of control because of factorssuch as a change in the properties of theincoming material (shift in mean).

Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Unstable and Stable Processes

Figure 36.7 Illustration of processes that are (a) unstable or out of control and (b)stable or in control. Note in sketch (b) that all distributions have lower standarddeviations and have means closer to the desired value. Source: After K. Crow.

Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Operating-Characteristics Curve used inAcceptance Sampling

Figure 36.8 A typical operating-characteristics curve used in acceptancesampling. The higher the percentage of defective parts, the lower is theprobability of acceptance by the consumer. There are several methods ofobtaining these curves.

Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Liquid-Penetrant Inspection

Figure 36.9 Sequence of operations for liquid-penetrant inspection to detect the presenceof cracks and other flaws in a workpiece. Source: Metals Handbook, Desk Edition.Copyright © 1985, ASM International, Metals Park, Ohio. Used with permission.

Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Magnetic-Particle Inspection

Figure 36.10 Schematic illustration of magnetic-particle inspection of a part with adefect in it. Cracks that are in a direction parallel to the magnetic field (such as inA) would not be detected, whereas the others shown would. Cracks F, G, and Hare the easiest to detect. Source: Metals Handbook, Desk Edition, Copyright ©1985, ASM International, Metals Park, Ohio. Used with permission.

Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Radiographic Inspection Methods

Figure 36.11 Three methods of radiographic inspection: (a) conventional radiography,(b) digital radiography, and (c) computed tomography. Source: Courtesy of AdvancedMaterials and Processes, November 1990. ASM International.

Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Eddy-Flow Current Changes

Figure 36.12 Changes in eddy-current flow caused by a defect in a workpiece.Source: Metals Handbook, Desk Edition, Copyright © 1985, ASM International,Metals Park, Ohio. Used with permission.

Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Basic Optical System for Detecting Flaws in Radiography

Figure 36.13 Schematic illustration of the basic optical system used inholography elements in radiography for detecting flaws in workpieces. Source:Metals Handbook, Desk Edition. Copyright © 1985, ASM International, MetalsPark, Ohio. Used with permission.