MSA Type 2 (Gage R&R)

“Measurement system uncertainty can have multiple components. In MSA Type 2, both repeatability and reproducibility are evaluated.

Objective
  • Assessment of measurement system capability
  • Determination of repeatability
  • Determination of reproducibility
  • Compliance with standard requirements
  • Compliance with supply agreements
  • Validation of measurement data
berg_glossar_zielsetzung

Procedure:

Purpose of the measurement system

▪ Is the measurement system for process monitoring or quality assurance?
▪ Which parts should be evaluated?
▪ What are the tolerances (Upper Tolerance Limit and Lower Tolerance Limit)?

Obtain at least 10 different units from the process

▪ These units should reflect the "typical" amount of process variation.
▪ The units must be labeled (numbered).

Select 2-3 operators

The operators selected for the MSA study should be the ones who actually perform these measurements in production.

Develop an experimental plan and conduct the investigation

1. The operators should receive the units in a random order.
2. Each operator should measure each part two to three times.

Analyze measurement data

ANOVA can be used to determine the overall uncertainty as well as the components of repeatability and reproducibility.

Analyze measurement data

1. The P/T ratio (Precision/Tolerance) indicates how well good and bad parts can be distinguished.

2. The Gage R&R value shows how effectively changes in process conditions can be detected within the process window.

Bewertungstabelle
P/T% GR&RBewertung
0 - 10%0 - 10%Messsystem ist fähig
10% - 30%10% - 30%Messsystem ist bedingt fähig
> 30%> 30%Messsystem ist ungeeignet

The Golden Rule of metrology states that the precision of a measurement system should not account for more than 10% of the tolerance window.

Formulas:

MSA Typ 2 - 1

MSA Lean Six Sigma

Figure 1: A “good” measurement system should use no more than 10% of the width of the tolerance window.

Tips:

▪ No action is required for a good measurement system.
▪ For poor reproducibility, eliminate the causes of variation between operators.
▪ For poor repeatability, it may be necessary to purchase a new measurement system.

With more than 4,000 projects and case studies, Alphadi is a leader in the field of Lean Six Sigma and Sales Process Engineering. We advise you holistically so that your goals are achieved sustainably and in the long term.

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