The Elsmar Cove Forum > Common Quality Assurance Processes and Tools > Capability, Accuracy and Stability - Process, Machine, etc.

1. Ppk vs Cpk - A Good, clear explanation and How Mini-Tab Handles Certain Statistics
2. A Cpk Brief - Don Winton Contribution
3. Questions on use of SPC, Ppk, Cpk during PPAP
4. Ppk - Capability calculation using the estimated sigma calculated from the Rbar/d2
5. What are the benefits pursued with the revision of CP when Process cpk >=3?
6. SPC and GD&T - Machined parts - Is Cpk is the correct index?
7. More GD&T - We can't compute Cpk using GD&T
8. Ppk or Cpk - Preliminary Process Capability vs. Process Performance
9. What is the difference between Ppk and Cpk
10. On-going capability - Can we decide for ourselves how often to measure cpk?
11. Combining high Cpk (3, 4 or 5) with a set of XR charts
12. Cp & Cpk - How are you calculating the standard deviation?
13. Cpk for one sided dimension - GD&T true position
14. Calculating Defect Rate (PPM) from a Cpk value
15. PPAP Rev 3 Cpk/Ppk - Bulk Suppliers - Aluminum, ingot, coil
16. Capability Studies - Fewest Number of Parts for a Capability Study
17. Process monitoring of portable & stationary oxygen units: Can we use Cpk, Ppk, SPC ?
18. Going for QS Cert but not ALL processes are at Cpk 1.33
19. Determining Cpk on a single sided tolerance dimension
20. Can I calculate Cpk from Cp and Cr?
21. Cpk and Ppk calculations for QS-9000 TE (Tooling and Equipment) Requirements
22. Increased positional tol. due to departure from MMC (Bonus)and calculation of Ppk/Cpk
23. Cpk's for five different dimensions on castings
24. Cpk or Ppk in packaging closure manufacturing?
25. Using Cpk for the purpose of determining sample size/frequencies
26. Cpk on Profile - Is it possible to a Cpk study on a profile? GD&T perspective
27. How do I calculate the percentage of errors, when I know min, max, mean, cp and CPK
28. Cpk higher than Cp - Explain the relationship and why this happens?
29. Capability index for one-sided specification? Cpk(max) = (USL-Xbar)/3*s ??
30. Is there any relationship between Cpk & Right First Time? First Pass Yield (FPY)?
31. Cpk value interpretation - What is the significance of Cpk value of 1.33?
32. Cp and Cpk - Cpk is an index that should be applied to a stable process
33. Cpk, cómo calcularlo?
34. High Cpk's and Control Charts - Is it justified to stop using control charts?
35. What causes Ppk to be greater than Cpk when a basic capability analysis is run?
36. Calculating Cp and Cpk on a Non-Normal Distribution
37. Cpk Vs DPM (Defects Per Million {aka PPM})
38. Cp/Cpk vs Pp/Ppk (Short term using population sigma) - Formulas to use?
39. Short Run - Low Volume Cpk Calculation
40. Process Standard deviations and equivalence of Cp & Cpk
41. Cpk for Individual Chart
42. Cpk calculation for short runs - Manufacturing FFC (flexible flat cable)
43. Cp, Cpk calculation for np chart - No USL or LSL - SMT Production
44. Reducing gaging frequency/High Cpk
45. Need help / feedback on Xbar/R charts and Cpk/Ppk applicability - Assemblies
46. Oddities of Cpk - Chicken parts
47. Attribute Charting - Where does Cp and Cpk come into the equation?
48. Using Cpk index for Accept / Reject Decisions
49. Cpk, Cmk in electronic assembly
50. Calculating the RFT using the Cpk value
51. Calculating Cp and Cpk for Product with only LSL (Lower Specification Limit)
52. Capability: Short Term or Long Term? Cpk= Long term and Ppk= Short term?
53. Calculating Cpk on a single sided (unilateral) tolerance
54. Cmk and Cpk - When will we need to calculate Cmk? Machine Capability
55. How do I calculate Cpk with a single Control Limit?
56. Cpk vs. Ppk - Long Term vs. Short Term - Capability vs. Stability
57. How much does Cpk > 1.33 represent in precentage of good pieces?
58. Tolerancing based on Cpk Data - Spreadsheet Attached
59. Is it possible to determine the Cpk value from Cp and Cr values?
60. Cp, Cpk, Sp, Spk for a one-sided minimum specification
61. Pp and Ppk indices - Is it statistically possible to have a Ppk greater than Pp?
62. Evaluating software that measures Ppk, Cmk, Cpk, PPI, etc.
63. Control Chart CpK dilemma - Defect Per Unit data on a single production line
64. When to use Ppk/Pp and Cpk/Cp - Difference between population and sample
65. What is the 'k' in Cpk?
66. Ppk and Pp on unilateral or unequal tolerance - DCx says Pp can not be calculated
67. SPC on Wave soldering machine - Cp and Cpk analysis - Soldering pot temperature
68. Training tools wanted for CPK and PPK
69. Software Calculation Errors for Cp and Cpk With Unilateral Tolerances
70. Which should be decided first : Cpk or all equipment/technician GRR
71. Ppk formula - Can some one please help me - I have attached the sheet.
72. Cpk analysis for +.000/-.004 problem
73. Ppk - Seeking short-term study examples - Chronically unstable processes
74. Is Cpk a good measure of capability? There are several shortcomings of Cpk
75. If there is no demands of (Cpk etc) limits on SC at PPAP?
76. Capability study - What Values do I have to input to calculate Cp and Cpk
77. Cpk - Relation between measurements and resulting tolerances - Trimming resistors
78. Evaluating Process Stability - Unstable Processes - Cpk/Ppk?
79. Is there a Cpk requirement for automotive industry stated in TS16949?
80. Could anyone tell me what is relation / difference in Cpk and Ppk
81. Is it possible to have a process that is too good? Cpk is 14.63
82. Seeking a Cpk vs z vs Pz Table
83. Cpk's, specifications and tiny sd's - Resolution of measurement equipment
84. Some questions about Cmk and Cpk
85. Does anyone know the conception of "Plant Cpk average"?
86. SPC Terminoloy & Jargon: Cpk, Ppk etc.: How did it evolve?
87. Attribute capability indices - Cpk and/or Ppk value for an attribute type of feature
88. Spc Question - When the Cpk value is bigger than 2.0
89. What is the formula I need to calculate Pp and Ppk?
90. Is Cpm (Taguchi's Index) Superior to Cpk and Ppk?
91. Cpk for 3D data - Capability study from CMM data- Need Help
92. What is the difference between Cp, Cpk and Ppk?
93. The Formulas of Ppk and Cpk in VDA4.1
94. Rp with a 1.33 min Cpk (Rp?) - Anyone know what Rp represents?
95. Cpk computation for Skewed Distribution
96. What should be the best control chart? Cpk study for assembly length
97. AIAG PPAP requirement on Cpk
98. Calculating Cpk/Ppk Simultaneously in SPC software
99. Analysis of Ppk data and calculations
100. TPPS ( torque process potential study) - How to & need Excel .xls Spreadsheet
101. Experience with DOE in machine capability study
102. Capabilty & samples - Why do we use a d2 (of 2.326) for a sample of 5 parts
103. What is the meaning of "k" in Cpk and Ppk? And Cpk vs. Ppk
104. Process Capability - Bilateral vs. Unilateral Tolerances
105. Is it possible to get a negative Cpk value?
106. Which system of inspection will be better attribute type or the variable type?
107. Process capability for blended fluids? PPAP book section 1.2.2.9.1, page 6
108. Need a help in finding a research paper - Patel, J. K. (1986) Tolerance interval
109. Capability studies in Process Plants - E-coat of galvanized flat carbon steel coils
110. P-value is 0.05 - Normal or non-normal data?
111. Low Process Capability - Cpk - Man-made part - What to do?
112. What is the value of Cpk for a new process?
113. Is a machine capability the right thing to do Next? Laser measuring machine
114. Tolerance intervals - Asked to provide a tolerance for a manufacturing process
115. Confused about the machine capability index Cmk
116. Tensile made critical characteristic, but Cpk? High rate of rejection in a part
117. Process Capability Data (TS16949 8.2.3.1) - How often should it be reviewed?
118. Ppk/Cpk for geometrical true position of hole with MMC
119. Calcuating a one sided (LSL) Cpk for Proccess Capability
120. Charting Bi, Tri or More Modal Distributions to combine results from two machines
121. Differences between Machine Capability and Product Capability studies
122. Ppk sampling method - Does data for Ppk have to been continuous?
123. Analysis of non-normal stratified data for cpk/ppk? Rupture test
124. Process capability or Process control - Which comes first?
125. Use of an outlier in calculating Cpk/Ppk
126. Necessary to Write a Process Capability Procedure? ISO9001
127. Machine Capability vs. Process Capability - Differences?
128. Ppk of non-normal bounded proccess, one sided specification
129. Can CPK be a good manufacturing processor’s quality objective?
130. Process Control - Force in compression moulding of rubber keypads
131. Cp vs. Cpk - A Visual Animation and Related Discussion Threads
132. Definition of Special Characteristics Delta C and Delta S - Need for Customer Audit
133. Quality Control Index - We thought that Cpk or Ppk would be good choices
134. How do you identify your heat treat capability study samples?
135. Machine short term capability study with Cmk index in automotive industry
136. Reason for pre-production machine/process capability studies / SPC during production
137. When do you reduce SPC sampling? And How?
138. Real life example of the difference between Cpk and Ppk
139. Capability Study for Radii of laser cut pockets - 0.030" radius
140. A question about Cpk and Cmk - Can we use Cpk to replace Cmk?
141. Cpk Help needed - Explain to me where I made a mistake
142. Customer is telling me my Cpk calculation is incorrect
143. How to compare Cpk and ppm (bad pieces)
144. Is it acceptable to use S bar to compute CPK?
145. What is the difference between UCL, LCL and Cp, Cpk
146. Using Pin Gages as a Measurement Tool for Ppk/Cpk studies
147. Sub Group Size of 1 or 5 - Is there a difference in the Long run?
148. Cp and Cpk for Dispenser product
149. Process Capability Training Exercise
150. Composite Process Capability Index - Cpk is not additive
151. Process capability worksheet - how to create the Bell Curve?
152. What Capability Index should I use? SMT Application
153. Pre Production Parts Sampling for Cpk
154. Which SDLC (Systems Development Life Cycle) phase does Quality Assurance Participate
155. How can I calculate Cp & Cpk and make a control chart for maintenance activities?
156. What Tool(s) to Use to Create a Cpk Chart from Data
157. Cp, Cpk, Dpm, or other? Diameter of a Hole - Non-Normal Distribution
158. Upper and Lower Limit Calculation with Capability Formula - Product Weight
159. Capability Study Template
160. Capability Study on Extruded Alumin(i)um - How would one define a "batch"?
161. Time Study Std/Books that define minimum requirements for conducting time study?
162. Process that is Not Stable vs. Not Statistically Capable - Differences
163. Validation of Stability Testing for Sutures
164. Measuring Capability on a One Sided Variable (Surface Finish)
165. Calculation/math to find 1.33 Cpk
166. Cpk and MSA study for Chemical Production Line
167. What does a Process Capability Index of greater than 1 suggest?
168. Accelerated Stability Studies - Duration and Conditions - Class III Medical Device
169. Small Lot, Large Part Run Chart - Expressing Cp / Cpk
170. Fastener Sorting Capability
171. Cpk Studies for Concentricity - Dimension that is spec'd 0.0 - .03
172. Small Lot Sizes - 30 a month - Cpk - Very large fabrication
173. Capability Study on Attribute Data? Visual Inspection
174. Suitability and Capability of Measurement Equipment
175. Cmk (Machine Capability) - Case study
176. Why is Cpk = lower of (USL-Xbar)/3sig & (Xbar-LSL)/3sig ?
177. How to calculate the capability when the tool life is low
178. XRF Capabilities - Correlating 2 different XRF machines - Ni/Au parts
179. Process Capability on go / no-go gage?
180. Assumptions with Small Sample Sizes
181. Poor Capability - Electric torque screwdriver
182. Expansion M/C Capability
183. Machine GR&R (Gage R&R) - Capability Study
184. Gage R&R study frequency - How often should a Gage R&R be performed?
185. Capability calculation on unequal bilateral tolerances?
186. Individual & MR chart - Ppk or Cpk?
187. Cpk Graphs - what information should it contain?
188. Establishing Thickness Specifications from Measured Data
189. When shall I recalculate control limit?
190. Condition of 100% inspection in organization.
191. Capability question from CQE exam
192. MSA and Gage R&R for Measuring Microscope
193. How to plan new capacity for a cement tile factory
194. MSA (Measurement System Analysis) on automated machine
195. Using Ppk to set up Control Plans - Injection molding
196. Method to compute Cpk for Attribute Data?
197. Establishing and controlling process capability - Meaning of Phrases
198. Determining a Good Variable for Small Scale Weld Integrity Capability Evaluation
199. ASQ CSSBB Question on Cpk and PPk , can you solve it ?
200. MCA calculation - problem with Cm Cmk and boundaries
201. Is my Cpk calculator answer valid?
202. Transfering Cpk specification to 100% inspection specifications
203. Process controls on attribute data - Chrome plating manual buffing line
204. Process Impact Validation Testing - Polishing process
205. Capability Analysis (Cpk) of torque driver process
206. Automated paint process control on conveyerized lines - Million dollar question
207. Yield monitoring - Kg in and Kg out
208. Sigma Level and Capability - What are Ppu, Ppl, Sigma Level, Sigma Capability
209. Process Capability study of CNC Machining Process
210. Throughput time measurement Cpk summary
211. Does anyone know what is involved in a HiPot capability study?
212. Capability Index for Furnaces - CQI-9 Assessment
213. Cpk Calculation - Tolerance to maintain 1.33 & 1.67 Cpk respectively
214. New Japanese automotive launch (composite plastics molding) - Acceptable Cpk?
215. Is Cpk calculation of dBA (noise level) valid?
216. Process Capability for Attribute Data - Excel .xls spreadsheet wanted
217. Is the normal Cpk calculation applicable for data with positive & negative values?
218. Cpk and Ppk template wanted
219. Cpk / AQL relationship (Cpk tending towards AQL 1.0%)
220. Capability Study on a New Machining Process - Issues
221. Cpu & Cpk can be calculated the same?
222. Help with capability assessment
223. Use SPC to Calculate Correlation Device Tolerance - Hybrid Electronic Components