Anova Gage R And R

View this Gage R&R example case study to understand. There isn't enough part variation to use the Average and Range Method or the ANOVA method to calculate Gage R&R. A site dedicated to helping with Gage R&R setup, analysis and interpretation. Gage R&R Solutions. Home; Articles. Variable Data ANOVA Gage R&R calculator.

A measurement systems contains variation from three main sources: the parts or products being measured, the operator (aka appraiser) taking the measurements and the equipment used to perform the measurements. A Gage Repeatability and Reproducibility ( Gage R&R) study is used to identify the contribution of each of these sources of the variation in the measurement process (called precision).

The main focus of the study is on determining whether the measurement system is adequate for its intended use. Such a study evaluates several parts that are repeatedly measured (called trials) by multiple operators. A typical study is done by three operators who measure 10 parts at least three times each. The level of variation is then calculated among the operators and parts, across the trials. The operators should randomly sample the production across all the major sources of process variation (parts produced, equipment used, equipment calibration, shift, time between measurements, etc.). It is essential that they choose part samples that represent the true variation of the production process; otherwise the study will be worthless.

The actual analysis is conducted using two factor ANOVA. Example 1: Conduct a Gage R&R analysis for the data in Figure 1, which shows the measurements (Meas) done by two operators (Op) on five parts (Part) based on two trials. Figure 1 – Data for Gage R&R study You can conduct the analysis by performing a two fixed factor ANOVA as described in section 16.2 and 16.2a.

The ANOVA output is shown in Figure 2, although the data in range J13:N23 are not part of the ANOVA output, but have been added (as described below) to complete the Gage R&R analysis. Figure 2 – Gage R&R using ANOVA Note that the error term has been relabeled Repeatability (cell J10) and that the alpha value has been set to 25% (cell O5). Since the interaction effect (i.e. Operator*Part) is not significant (cell P9), the ANOVA output needs to first be modified by including the interaction values in the Repeatability term, as shown in the top part of Figure 3.

Thus, cell S9 contains the formula =K9+K10, cell T9 contains the formula =L9+L10 and cell U9 contains the formula T9/S9. Figure 3 – Gage R&R based on modified ANOVA We now explain the Gage R&R report shown in the bottom part of Figure 3.

Figure 4 describes the value of each of the sources of variability (i.e. The Variation column, column S). Column T shows the percentage of each variation component (divided by the Total Variation in cell S21). Column U shows the standard deviation of each variation component (i.e. The square root of the corresponding variation component) and column V shows the percentage of each of these standard deviations (divided by the total standard deviation).

Create Gage R&R (Crossed Worksheet) • To create a blank Gage R&R worksheet, click SigmaXL >Measurement Systems Analysis >Create Gage R&R (Crossed) Worksheet. A crossed Gage R&R study means that every operator/appraiser will measure every part/sample. • The default settings are 10 Parts, 3 Operators, 3 Replicates with Parts and Operators randomized. Clicking the Reset button will restore the dialog to these default settings. • Part and Operator names can be edited. The following worksheet is produced: • Your worksheet order will be different due to the randomization.

The results of the Gage R&R study are entered in the yellow highlighted Measurement cells. Analyze Gage R&R (Crossed) • Open the file Gage RR – AIAG.xls.

This is an example from the Automotive Industry Action Group (AIAG) MSA Reference Manual, 3rd Edition, page 101. Note that parts were measured in random order, but the worksheet is given in standard order. • Click SigmaXL >Measurement Systems Analysis >Wic Reset Keygen Free Download here. Analyze Gage R&R (Crossed). The data worksheet is recognized by SigmaXL and highlighted automatically. • Select Part,Operator OperatorOperator and Measurement as shown. Check Display Multi-Vari & X-Bar R Charts. Check Tolerance/Historical StDev (Optional) and enter 8 for the Process Tolerance Upper-Lower Spec.

The following Gage R&R Study Report is produced: • The first ANOVA table shows that the Operator * Part Interaction is not significant with the P-value = 0.9741 (greater than the alpha-to-remove value of 0.1). The second ANOVA table shows the results excluding the Part * Operator Interaction. • The cells shaded in light blue highlight the critical metrics: Gage R&R% Total Variation (also known as%R&R) and%Tolerance: 30% indicates an unacceptable measurement system.

The Number of Distinct Categories should be at least 5. Initial analysis shows that this is a marginal measurement system. (Traditionally NDC is truncated to an integer value, but SigmaXL reports a more informative one decimal place). • SigmaXL also reports the confidence intervals for the Gage R&R metrics. Note that when the confidence intervals are taken into account, it is possible that this measurement system is totally inadequate. This strongly suggests that the measurement system needs to be improved but it also points out the weakness of the traditional Gage R&R study with 10 Parts, 3 Operators, and 3 Replicates. These sample sizes will typically yield wide confidence intervals.

For statistical details of the Gage R&R confidence intervals see Burdick, R. K., Borror, C. M., and Montgomery, D. C., “Design and Analysis of Gauge R&R Studies: Making Decisions with Confidence Intervals in Random and Mixed ANOVA Models”, ASA-SIAM Series on Statistics and Applied Probability, 2005.

• Click on the Gage R&R – Multi-Vari Sheet tab to view the Multi-Vari Chart: The Multi-Vari chart shows each Part as a separate graph. Each Operator’s response readings are denoted as a vertical line with the top tick corresponding to the Maximum value, bottom tick is the Minimum, and the middle tick is the Mean.

The horizontal line across each graph is the overall average for each part. • Click on the Gage R&R – X-Bar R Sheet tab to view the X-Bar & R Chart: When interpreting the X-bar and R chart for a Gage R&R study, it is desirable that the X-bar chart be out-of-control, and the Range chart be in-control. The control limits are derived from within Operator repeatability. The Range chart indicates a problem with Operator B being inconsistent.