Manufacturing statistical process control in the presence of multiple batch effects

Patent metadata

Field	Value
Publication number	US-10928801-B2
Application number	US-201816184293-A
Country	US
Kind code	B2
Filing date	Nov 8, 2018
Priority date	Nov 8, 2018
Publication date	Feb 23, 2021
Grant date	Feb 23, 2021

Abstract

Techniques for qualifying for use in an overall manufacturing process items produced by a bulk manufacturing process that has a plurality of batch effects are presented. The techniques can include obtaining a collection of items produced by a bulk manufacturing process that has a plurality of batch effects; measuring a quantifiable property of a sample of items from the collection of items; developing a linear mixed model for the quantifiable property based on the measuring; determining a statistical process control standard deviation for the collection of items based on the linear mixed model; computing a statistical process control parameter from the statistical process control standard deviation; determining that at least a portion of the collection of items conform to the statistical process control parameter; accepting at least a portion of the collection of items; and using at least a portion of the collection of items in the overall manufacturing process.

First claim

What is claimed is:

1. A method of qualifying for use in an overall manufacturing process items produced by a bulk manufacturing process that has a plurality of batch effects, the method comprising:
obtaining a collection of items produced by the bulk manufacturing process that has the plurality of batch effects;
measuring a quantifiable property of a sample of items from the collection of items;
developing a linear mixed model for the quantifiable property based on the measuring;
determining a statistical process control standard deviation for the collection of items based on the linear mixed model;
computing a statistical process control parameter from the statistical process control standard deviation;
determining that at least a portion of the collection of items conform to the statistical process control parameter;
accepting at least the portion of the collection of items; and
using at least the portion of the collection of items in the overall manufacturing process.

2. The method of claim 1 , wherein the collection of items comprise a plurality of forged metal parts.

3. The method of claim 2 , wherein the plurality of batch effects comprise at least a heat treatment batch effect and a mill heat batch effect.

4. The method of claim 1 , wherein the statistical process control parameter comprises a process capability index requirement.

5. The method of claim 4 , further comprising implementing a statistical process control reduced sampling plan for at least one future collection of items produced by the bulk manufacturing process that has the plurality of batch effects.

6. The method of claim 4 , wherein the process capability index requirement is of the form

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B represents a number of batch effects, J represents a set of possible batch effect level combinations from all batch effects, represents a standard deviation for batch effect i, represents a standard deviation representing a within-batch batch variation, n j represents a sample size of items in batch effect level combination j, and t n*−1,C 0 √{square root over (n*)},1−α represents a (1−α) quantile of a non-central t-distribution with n* degrees of freedom and non-centrality parameter C 0 √{square root over (n*)}, where α is a Type I error rate associated with a confidence level.

7. The method o

Assignees

• Boeing Co

Inventors

• Jones Lindsay L W
• Cox Kelsea
• Lawton Robert M

Classifications

• G05B2219/32191

  Real time statistical process monitoring · CPC title

• Y02P90/02

  Total factory control, e.g. smart factories, flexible manufacturing systems [FMS] or integrated manufacturing systems [IMS] · CPC title

• G05B19/41875 Primary

  characterised by quality surveillance of production · CPC title

• G05B2219/32368

  Quality control · CPC title

• G05B2219/42001

  Statistical process control spc · CPC title