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cpk (related to process capability)

  1. J

    AIAG PPAP: Acceptance Criteria for Initial Study (page 9, 4th edition)

    Level 3 PPAP Can somebody please explain "initial study'? Does this include annual PPAP where we submit Cpk? Does it include anytime a PPAP is submitted - that Cpk must be met not matter what? My interpretation is that Cpk must be met and if the PPAP is going to be late because Cpk cannot be...
  2. F

    CpK on a manufactured assembly?

    Greetings, I'm new to the QA world and a customer is requesting a CpK on a manufactured box build assembly as part of their PPAP. Now I'm familiar with doing a CpK on items with actual measurable upper and lower limits but I'm a bit unsure as to where to start with this request. Essentially...
  3. O

    P-Value less than 0.05. but everything else in control

    Hello guys, I have a question about a Cpk output. My two control charts (Mean/Range) are in control. No points beyond control limits, my histogram looks well, similar to a normal bell, symmetrical. Cpk and Ppk indices meet my customer's expectations too. But P-value is less than 0.05. How can...
  4. Q

    How to perform Process Capability for true position

    The nominal for true position is 0. The print will call out a GD&T true position and allow you to go up to, let's say, .003. In cpk software, how do you reconcile this? If we put our LSL as 0 and our USL as .003, we don't get accurate results, because the LSL is NOT 0 - 0 is the nom. Is...
  5. M

    How is the Cmk and Cpk calculated?

    Hi In the machining process, after the 20 pieces have been manufactured, due to the increasing process characteristic, the grinding must be done to bring the characteristic closer to the target. In such cases, how is the cmk of the machine to be processed and cpk to be calculated?
  6. O

    Cpk for Unilateral Tolerance

    Hi Guys, I have three situations trying to do a Cpk with unilateral tolerance. I hope you guys can give me some advice on this. 1. I want to conduct a CPK for a diameter that is 10.0mm +0.1 -0.0 2. I want to conduct a CPK for a diameter that is 10.0mm minimum (it does not have a maximum...
  7. B

    How to calculate CPK with n = 1

    Hi all. I was wondering how to calculate Cpk using Rbar/d2 with a subgroup size of n = 1. All of the d2 charts I have list a minimum d2 value set at n = 2. Should we use the Ppk standard deviation or some other value for d2? Thanks, Brad
  8. O

    CPK with a P value less than 0.005

    Hello everyone, I am a bit confused about a cpk study I am analysing (Attached). The cpk and ppk are very good. this is a tube cutter and we collected the data with a caliper. in the length 508.0mm the P value is 0.177 which means a normal distribution. But in the 156.0mm lenght P value is less...
  9. J

    Are Capability Requirement(s) Valid for All Characteristics?

    Dear all, beside of special characteristic (SC, CC, ...) there are always many other characteristics in the drawing (let's say "normal"). The process capability indices are usually evaluated and controlled for special characteristics only (+ some additionally defined char.) My question: Is...
  10. A

    Short Term vs. Long Term SPC Study - Where is Cp and Cpk Defined

    Hello all! There has always been a confusion regarding whether Cp,Cpk is for short term or long term. Although I came to know that Cp,Cpk is for short term and to be used during preliminary SPC study (Such as development stage), there is no reference available supporting this. I tried to...
  11. A

    Cpk Formula seems off, need help!?

    This is driving me nuts. I have not completed many CPKs before and previously I have used a template to calculate each data set. It was setup for only 30pc inspections, but the new customer needs a 35pc. So I attempted to modify my excel sheet to incorporate the extra parts. However I am getting...
  12. E

    Questions regarding Cpk Calculation - Should we be using LSL/USL or LCL/UCL?

    Hello, just a small question to which i can't seem to find an answer: For Cpk calculation, we have: Target 0% UCL 2% LCL -2% USL 4% LSL -4% when calculating Cpk, should we be using LSL/USL or LCL/UCL? also, if we have out of spec values somewhere within results, should they be left there to...
  13. M

    Process Capability in a High Precision Environment

    Hi Everyone, I just started introducing the automotive process control approach in a non-automotive, high precision manufacturing business. Immediately it's clear that many of the grinding tolerances (0.003mm) are very difficult to achieve and even harder to measure due to resolution issues...
  14. B

    Maximum Material Condition with Bonus - Determine Cpk for this one kpc

    I have a .005 true position tolerance with MMC. One of the readings is .0061 but bonus is .0077. How would I enter this to determine cpk for this one kpc? The .0061 is within the bonus tolerance of .0077, but the attached file shows what they want. Any help would be highly appreciated.
  15. Hami812

    Cpk Setting Tolerance - Cart before the Horse? (Wifi Routers)

    I'm struggling with a Colleague approach to something related to testing Wifi Routers who wishs to perform a Gage R&R on some Routers that have Wifi. There are numerous testers that need to be "Qualified" for production and a gage RnR is required. My colleague suggests, in order to set the...
  16. TarKEpa

    Calculating LCL, UCL, Cp, and Cpk in an Excel Spreadsheet

    Hi All; Kindly I need to make sure from my calculation in the attached sheet 1. I'm calculating the UCL and LCL for Product Overall Yield (Pharmaceutical), I used I-MR chart, 2. then, calculate Cp and Cpk. (This is before Improvement)...
  17. V

    Product Development - When to start calculating Process Capability

    product development goes through stages of strategy - prototype - scale - validation/verification; my question is, at what stage should we start calculating process capability index; and how to interpret them at each of the stages!.
  18. Proud Liberal

    Cpk on Position w/ MMC on Location and Size

    I have several bolt hole pattern FCF's with MMC on both the tolerance and feature size with the added wrinkle of no rotational alignment (datums only on a plane and a center of the bolt hole pattern). 1. How should the lack of fixed alignment system be handled w/respect to capability? 2. On...
  19. Mikael

    Combining FMEA, CP and Kano

    Hi Does it make sense to combine the Kano model with some version of FMEA and/or with process Capability (Cp/Ckp)?
  20. E

    SPC Production - Getting Cpk and Ppk

    Hello to all my friends. I need to make a control chart for analyzing (statistically) a dimension during 10 days production. I need to know the Cpk and Ppk . Does anyone have any examples please ? Thank you
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