Type-2 Study. Measurement system analysis in destra, version 11

Transcription

1 Type-2 Study Measurement system analysis in destra, version 11

2 Type-2 Study 1/25 Contents 1. Preface Basic information about type-2 study Performing a measurement system analysis according to type-2 study How to create type-2 study Adding type-2 study to an existing project Expand project structure Add a new data source for type-2 study Evaluating a DFQ file including data for type-2 study Creating a new project based on type-2 study Entering data for type-2 study in the values mask Documenting the analysed test process How to evaluate data according to type-2 study Evaluation criteria of type-2 study Resolution in per cent %RE Required minimum number of measurements min %GRR total variation of the measurement process in per cent How to open diagnostics graphics Value chart of individuals Value chart of the part s averages Value chart of interactions Value chart of deviations from the total average Value chart of variations Bar chart of the percentage variation (% total variation) How to create reports Report preview How to save a project...25

3 Type-2 Study 2/25 1. Preface This document shows how to conduct a measurement system analysis according to type-2 study in destra, version 11. All evaluation results the document shows are based on the Q-DAS Measurement Process Qualification (06/2013) evaluation strategy. In case your company applies a different evaluation strategy, the results might differ from the ones shown in this example. We also assume that you have the required statistical knowledge of measurement system analysis. Note: In case you do not have the required theoretical knowledge, we recommend you to attend the respective seminar first. Our affiliate TEQ Training and Consulting GmbH offers a wide range of suitable training courses. Find a suitable seminar at Note: Version 11 of destra introduced the Project Explorer. In case you do not know how to handle the Project Explorer, we recommend you to complete the Project Explorer case study first. Otherwise, you might have problems understanding the single steps we take and the single options we use.

4 Type-2 Study 3/25 2. Basic information about type-2 study Starting point is a product or process characteristic to be monitored. This characteristic has to meet two requirements for this application. 1. The characteristic to be monitored refers to a property whose values are a multiple of a physical unit. 2. The actual value of the characteristic to be measured remains constant under repeatability conditions and does not change in a measurement. In order to be able to trace the measurement system you analysed and the reason why you analysed it any time, you first collect all relevant information. 1. Part information: From which product / process do you take the measurement? Part number, part description, customer ID and customer name, drawing number and amendment status. 2. Characteristic information: Which characteristic of the product / process do you measure? Characteristic number as given in the drawing, characteristic description, measurement unit, lower specification limit of the characteristic and upper specification limit of the characteristic. 3. Measurement system information: Which measurement system takes the measurements? Identification number, description, resolution and site of operation. You should even record date / time and location. 2.1 Performing a measurement system analysis according to type-2 study Most guidelines recommend the following test set-up.

5 Type-2 Study 4/25 Operator: Two or three trained operators conduct the test. These operators will also be responsible for the serial measurement. Two or three trained operators measure 10 serial parts and take two or three repeated measurements. Order: Since you did not enter and evaluate the values in random order in the program, you can do without the recommended randomisation of trials. Repeated measurements: Each operator measures each item at least twice. Part selection: Select 10 or more produced parts / items whose characteristic values cover at least 80% of the characteristic s tolerance. In order to reach this aim, you can either include some items with a poor evaluation result and / or add items from various batches of the production process. Place of measurement on the items: Since you do not want to consider form and location deviations of the items as equipment variation, you should align the items properly before you take measurements. If possible, mark the respective measuring point(s) on the items and train operators to do so. Note: Marking measuring points is often dismissed since it is considered as unnecessary. The following example, however, shows the consequences. Example: A company records the characteristic diameter as a linear measure and uses a micrometre to take these measurements. The parts are measured once in each trial, at any place and in any position (alignment). So the variation of the diameter caused by form and location deviations at different points of the measuring object becomes part of the evaluation. Type-2 study considers this variation that occurs at different measuring points of the parts as equipment variation (EV). In short: The part variation is now assumed to be caused by the measurement system, even though it is not! Since the equipment variation is now inflated by the part variation, the equipment variation is excessively high and you cannot establish the system s capability.

6 Type-2 Study 5/25 3. How to create type-2 study When you create a data source for type-2 study, there are three different initial situations available. 1. You want to add a new type-2 study to an existing project. 2. You want to include an existing DFQ file in an existing project. 3. You want to start a new project based on type-2 study. We now have a look at each of these three cases. 3.1 Adding type-2 study to an existing project An existing project already contains structural elements and you have to be careful when you integrate new elements into this structure Expand project structure The following figure shows an existing project in the Project Explorer. It already includes an evaluation according to type-1 study. Now you want to add an additional evaluation according to type-2 study. You want to add type-2 study as a new work space node under the Measurement system analysis project phase. Right-click on the Measurement system analysis project phase node in the Project Explorer. Figure 3-1: Project Explorer showing an existing project A context menu opens and shows the Create work space option. Figure 3-2: Context menu of the Project Explorer

7 Type-2 Study 6/25 The Create new work space dialog box opens. Under Name you enter Type-2 study orifice nozzle diameter. Figure 3-3: Create new work space dialog box showing the name you entered The program now creates a new work space and you may focus on creating a new data source for type-2 study now. Figure 3-4: Project Explorer showing the additional work space node Add a new data source for type-2 study Click on the Type-2 study orifice nozzle diameter work space node in order to activate it. Now you select Start Create Measurement System Analysis Type-2 Study. The program opens the Measurement System Analysis Type-2 Study window. Here you enter the characteristic s specifications. Figure 3-5: Measurement System Analysis Type-2 Study window showing your entered data

8 Type-2 Study 7/25 After you entered the data, click OK to confirm your input. The program creates a new data source node in the Project Explorer right below the activated work space node. In addition, the values mask opens for data input. Figure 3-6: Program after creating an analysis for type-2 study Please switch to chapter 3.4 on page 10 in order to become acquainted with how enter and evaluate data. 3.2 Evaluating a DFQ file including data for type-2 study Figure 3-7 shows the project structure of an existing project. Note: Chapter on page 5 gives an example of how to extend the project structure of an existing project. Now we assume that you already added the Type-2 study work space node to the existing project structure. Activate Type-2 study node in the Project Explorer. The program will now load the file you open as a data source below the existing work space node. Figure 3-7: Existing project structure with type-2 study added before loading the DFQ file Now you select File Open.

9 Type-2 Study 8/25 The Windows dialog box for opening files opens. Select CAS_destra_v11_gc_002.dfq and click Open. Figure 3-8: Windows dialog box for opening files, select CAS_destra_v11_gc_002.dfq Now you have to select the module in which you want to open this file. Figure 3-9: Open data in module dialog box with the Measurement System Analysis module selected Select Measurement System Analysis from the drop-down menu under Available modules and confirm your choice by clicking OK. Figure 3-10: Values mask after loading the DFQ file

10 Type-2 Study 9/25 The program added the CAS_destra_v11_gc_002.dfq data source in the Project Explorer and opened the values mask including the data of this data source. Please switch to chapter 4 on page 14 to continue data evaluation based on type-2 study. 3.3 Creating a new project based on type-2 study You analyse a drive shaft whose outside diameter shall be measured by means of a micrometre (25 mm 50 mm). Since a micrometre is a hand tool, you have to expect some appraiser variation. This is the reason why you selected type-2 study including two trained operators who measure each of 10 series parts twice. Please consider that you measurement system successfully established its capability in type-1 study. After you opened destra, select File New project Measurement system continuous Type-2 study. Figure 3-11: Measurement System Analysis Type-2 Study window Enter the data of the following table in the Measurement System Analysis Type-2 Study window. Field Value Name Outside diameter Unit mm Nominal size Lower specification limit LSL Upper specification limit USL Number of operators k 2 Number of trials r 2 Number of parts n 10 Table 3-1: Values to be entered in the Measurement System Analysis Type-2 Study window After you entered the data, click OK to confirm your input. The program creates a project structure in the Project Explorer.

11 Type-2 Study 10/25 Figure 3-12: Project Explorer including the automatically created node elements The root element is the project node. The program creates a project phase node right below the project root node. The next subordinate node is a work space node and the last node in the graphic above is the data source node. Tip: Right-click on a node element to open a context menu. This menu includes an option for renaming the selected node element. Always select a clear name for these elements in order to be able to identify the contents they contain. Figure 3-13: Project Explorer after renaming the automatically created nodes 3.4 Entering data for type-2 study in the values mask The following data for type-2 study are available for download at our website. Select the text file CAS_destra_v11_gc_002.txt to download it and open the file in Notepad. Copy the data and paste it into the values mask. Figure 3-14: Values mask showing the measurement results

12 Type-2 Study 11/25 The following table shows the values once again for a better readability. type-2 study: outside diameter in mm Part no. Operator A Operator B Measurement 1 Measurement 2 Measurement 1 Measurement Table 3-2: Measured diameters in mm two operators measured each of 10 parts twice 3.5 Documenting the analysed test process When you require the values and results later again (e.g. in quality audits or for a call on customers) we will be pleased to be able to assign them to the correct test equipment and the correct characteristic / part. This is the reason why you should enter additional data in the parts mask and characteristics mask. Open the parts mask by selecting Edit Mask Parts mask. Figure 3-15: Parts mask including specifications making the part assignable

13 Type-2 Study 12/25 Enter the following data in the parts mask. Field Value Part number T4711 Part description Drive shaft Manufacturer number QDAS Manufacturer name Q-DAS GmbH Weinheim Material description X12CrMoS17 Drawing number S Drawing - amendment Rev. 01 Test facility reason for test Acceptance of measurement system Test begin Test end Contract 0815 Contractor internal Customer number 007 Customer name Prototyping Table 3-3: Information making the part assignable Open the values mask by selecting Edit Mask Characteristics mask. Now we add information about the measurement equipment and others. You thus want to establish the capability of the measurement equipment by using type-2 study. Figure 3-16: Characteristics mask including information about the applied test equipment

14 Type-2 Study 13/25 The following table shows the values once again for a better readability. Field Characteristic number Description Gage number Gage description Group Test location Table 3-4: Input for the characteristics mask Value M1 Length BMS-027 Digital micrometre (25-50) mm HM-022 WSP-42 Note: In general, it is possible to link the input fields of the parts and characteristics masks to the catalogue fields of the database (however, this requires the Q-DAS Form Designer). In case you linked these fields to the respective database fields, the user can select the catalogue information stored in the database from a drop-down menu.

15 Type-2 Study 14/25 4. How to evaluate data according to type-2 study After you entered your data, you save the project. Select File Save project file as Select the respective storage location in the Windows dialog box and select a clear name for your project file. Before you start the evaluation, click in the Project Explorer on the data source to be evaluated. This click activates the correct data source for analysis. Now you select Start Evaluation Standard procedure. First, you have a look at the new structure in the Project Explorer. A blue session node called Default Session was appended to the data source node. Figure 4-1: Project Explorer The Form sheet Design 3 window opened automatically. It shows the analysis results of type-2 study. Note: The results of this case study are all based on the Q-DAS Measurement Process Qualification (06/2013) evaluation strategy. The single variation components are determined by means of mathematical procedures based on the twofold analysis of variance with random effects. The evaluation algorithms and requirements of this automated evaluation of results according to type-2 study are specified in the evaluation strategy. Different organizations normally apply different settings in the evaluation strategy. In case your company applies a different evaluation strategy, the results might differ from the ones shown in this example. This is not a bug.

16 Type-2 Study 15/25 Figure 4-2: Form sheet Design 3 window showing the evaluation results of type-2 study The upper part of the window shows a table containing the components causing variation. The total variation of this test was thus resolved into single components. Figure 4-3: Table showing the causes of variation that occurred in the test All columns of the table are self-evident except for the last one. It shows the components percentage share of variation (= standard deviation of the respective component) referring to the total variation (= standard deviation of total variation). %EV = EV AV GRR PV 100 %, %AV = 100 %, %GRR = 100 %, %PV = 100 % TV TV TV TV Note: The standard deviation for total variation is calculated from TV = Tol when the tolerance is the reference figure. Page 122 of the AIAG Measurement System Analysis manual, 4 th edition 2010 provides you with some details about this estimator. 6 Figure 4-4: Table of the overall evaluation result

17 Type-2 Study 16/25 The smiley indicates that the measurement process met the requirements. Look at the last line of the overall evaluation result. It says Measurement system capable and provides some symbols in brackets. These symbols refer to the evaluated requirements of type-2 study. The following chapters focus on the single criteria. 4.1 Evaluation criteria of type-2 study The Q-DAS Measurement Process Qualification (06/2013) evaluation strategy includes the following three criteria for evaluating the analysis results according to type-2 study. Resolution in per cent %RE Required minimum number of measurements min Gage repeatability and reproducibility %GRR Note: Evaluation criteria and minimum or maximum values are adjusted individually in the evaluation strategy according to customer requirements. In case your company applies a different evaluation strategy, the results might differ from the ones shown in this example Resolution in per cent %RE The resolution in percent %RE specifies how many different characteristic values can be recorded within the tolerance. The upper limit in the evaluation strategy is %RE max = 5%. In case the tolerance is set to 100%, a resolution of %RE = 5% means that you may record 20 different values within the tolerance (100% / 5% = 20). You meet this requirement when the actual resolution %RE is less than or equal to the upper limit. %RE = RE Tol % = 100 % = 4.76 % 5 % The analysed measurement system thus meets this requirement Required minimum number of measurements min The product of the number of parts n multiplied by the number of trials r multiplied by the number of operators k leads to the number of measurements. According to the evaluation strategy, the number of measurements is set to min = 30. In this case: n r k = = 40 > min = 30 The requirement for the minimum number of measurements is met.

18 Type-2 Study 17/ %GRR total variation of the measurement process in per cent You use mathematical calculation methods based on the analysis of variance to resolve the variation into single variation components. Repeatability Reproducibility Part variation Two variation components belong to the measurement process; they are generally referred to as repeatability and reproducibility. Their full description is gauge repeatability and reproducibility (acronym: GRR) referring to the total variation of the measurement system. σ GRR = σ EV 2 + σ AV 2 = = % GRR = 6 σ GRR Tol mm 100 % = 100 % = % mm The evaluation strategy includes limits for statistic %GRR. Total variation of measurement system Result of process analysis %GRR %GRR < 15% Measurement system is capable. 15% %GRR < 30% Measurement system is conditionally capable. %GRR 30% Measurement system is not capable. Table 4-1: Requirements according to Q-DAS Measurement Process Qualification (06/2013) The measurement system is capable according to this evaluation. Note: Please consider once again that evaluation criteria might vary from organisation to organization. The limits specified in the Q-DAS Measurement Process Qualification (06/2013) evaluation strategy are based on the recommended maximum values Q MS_max = 15% and Q MP_max = 30% as given in VDA Verband der Automobilindustrie Quality Management in the Automotive Industry Capability of Measurement Processes VDA 5, 2 nd completely revised edition 2010

19 Type-2 Study 18/25 5. How to open diagnostics graphics Diagnostics graphics help you to identify systematic patterns in the data indicating possible errors and sources of interference in the experiment. 5.1 Value chart of individuals This graphic shows the original values of the measurements taken by both operators. Select Graphics Individual characteristic graphics Value chart. Figure 5-1: Value chart of individuals per operator and part Use this graphic to check whether the parts show a sufficient variation within the tolerance. Parts shall cover about 80% of the entire characteristic tolerance. This example meets the requirement.

20 Type-2 Study 19/ Value chart of the part s averages Compared to the value chart of individuals, this graphic calculates the averages of both individuals (first and second measurement per part). It thus shows the part s averages per operator. Select Graphics Individual characteristic graphics Value chart Averages. Figure 5-2: Value chart of averages Use this graphic to check whether both operators reached about the same measurement results. Ideally, the charts of the two operators are congruent. 5.3 Value chart of interactions This graphic displays the value charts of the part s averages for each operator in a different colour. Operator A is displayed in blue and operator B is shown in red. There are not any interactions available when the charts of the two operators are congruent or almost congruent. However, if the graphic shows skew lines (instead of parallel lines), the graphic indicates interactions between operators and parts. Select Graphics Individual characteristic graphics Further Interaction plot.

21 Type-2 Study 20/25 Figure 5-3: Interaction plot 5.4 Value chart of deviations from the total average Here is the calculation of deviations for the first part only. This calculation, however, needs to be performed for each of the 10 parts. This is what the software does. In this example, there are four measured values available for the first part. They were recorded in the first and second trial of operator A and in the first and second trial of operator B. Operator A, first part, first trial Operator A, first part, second trial Operator B, first part, first trial Operator B, first part, second trial x A.1.1 = mm x A.1.2 = mm x B.1.1 = mm x B.1.2 = mm You calculate the total average of the first part from these four measurements. x 1 = Now you calculate the deviations. Operator A, first part, first deviation ( )mm 4 = mm x A.1.1 = x A.1.1 x 1 = ( ) mm = mm Operator A, first part, second deviation x A.1.2 = x A.1.2 x 1 = ( ) mm = mm

22 Type-2 Study 21/25 Operator B, first part, first deviation x B.1.1 = x B.1.1 x 1 = ( ) mm = mm Operator B, first part, second deviation x B.1.2 = x B.1.2 x 1 = ( ) mm = mm Select Graphics Individual characteristic graphics Value chart Deviations. Figure 5-4: Value chart of deviations from the part s total average the blue line refers to the first trial and the red line to the second one Use this graphic to find out whether the measured values of the operators were too high or too low. The scale of this graphic makes it easier to answer questions such as Does only one of the two operators always show a positive deviation? or Does only one part lead to the highest deviations?. 5.5 Value chart of variations In order to calculate variations, you use the same calculation methods as for calculating deviations (see chapter 5.4 for further information). Select Graphics Individual characteristic graphics Value chart Variations.

23 Type-2 Study 22/25 Figure 5-5: Value chart of variations the blue line represents the two trials of operator A whereas the red line refers to the trials of operator B Use this graphic to find out whether the first trial varies considerably from the second trial or not. There are considerable variations between the first and second trial. The graphic makes it easier to answer questions such as Does only one of the two operators always show considerable variations? or Does only one part lead to the highest variations?. 5.6 Bar chart of the percentage variation (% total variation) This graphic is a bar chart showing the percentage standard deviations of the components repeatability (%EV), reproducibility (%AV) and total variation of the measurement system (%GRR) referring to the total variation. Select Results Analysis % variation measurement system. Figure 5-6: Graphic of the percentage variation (% total variation according to MSA)

24 Type-2 Study 23/25 6. How to create reports The program provides you with a predefined report for type-2 study. You can have a look at the preview before you print the report. 6.1 Report preview Open the preview of your report by selecting Start Reports Report preview. The program opens the Report selection window where you select the GC Type 2 Characteristic Report template and confirm your choice by clicking OK. You may also open the preview directly by double-clicking the GC Type 2 Characteristic Report template. Figure 6-1: Report selection window with the GC Type 2 Characteristic Report template selected The program now opens a preview of the GC Type 2 Characteristic Report. Right-click on this window to open the context menu.

25 Type-2 Study 24/25 Figure 6-2: Report preview GC Type 2 Characteristic Report window with a context menu opened by rightclick Use the options in the context menu to print the report or save it as a PDF file.

26 Type-2 Study 25/25 7. How to save a project Finally, you save the project by selecting File Save. The program now saves the project in the Q-DAS project file format (filename.qpf). When you open the project file again later on, all data and results will be available to you. Tip: If you want to save your data in the Q-DAS ASCII transfer format (filename.dfq), you first click on the respective data source in the Project Explorer and select File Save Save as