Husaria wingLevinson Productivity Systems, P.C.
William A. Levinson, P.E.  Principal
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Online and downloadable Excel spreadsheets

The following freeware is subject to the following conditions:

  1. All spreadsheets are copyrighted, and all rights are reserved.
  2. You may download and distribute them freely, provided that all copyright and authorship information is left in place.
  3. This freeware carries no warranties, express or implied, regarding fitness for use.
    • Your remedy for any dissatisfaction is a full refund of your purchase price :-)
    • No freeware offered here constitutes engineering advice or an engineering design service. Such services must be rendered personally, or under the direct supervision of, qualified engineers.
  4. The following spreadsheets should work in Internet Explorer.
    • You may be asked if you want to download and install a .dll file. ("Click Here to install the Office XP Web Components")
    • The spreadsheets can also be downloaded for use on computers in your workplace
PRE-Control (more details here)
  • Unlike traditional statistical process control, PRE-Control makes no assumptions about the underlying statistical distribution, nor does it require any historical information about the process. 
    • It is therefore useful for process startups for which no prior process history is available.
    • •The PRE-Control chart is a very simple visual control.
  • To qualify the process, measure parts until five consecutive pieces are in the green zone.
    • Take periodic samples of two pieces.
    • If both are in the green zone, or one is green and one is yellow, continue to operate the process.
    • If both are in the yellow zone (same side of the nominal), the process requires adjustment.
    • If either is in the red zone, stop the process because it is making nonconformances.
    • Re-qualify the process (5 consecutive pieces in the green zone) after an adjustment.
  • If the two pieces are in the yellow zones on opposite sides of the nominal, this could be due to excessive process variation.
The downloadable Excel spreadsheet includes the following innovative feature. Cells turn green, yellow, or red as the operator or inspector enters each measurement, thus providing an immediate visual control on the status of the process. The spreadsheet also determines whether the qualification run, or periodic sample of 2, passes or fails.
PRE-Control is available for three applications:
  • Two-sided specification: nominal is best (interactive Web page for Internet Explorer; conditional cell colors do not, however, seem to work)
  • One-sided specification: minimum is best
  • One-sided specification: maximum is best

visitors since 15 January 2009