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Chapter 3 Step-by-Step Tutorial 61

Chapter 3

Step-by-Step Tutorial In this chapter, you will learn the basic steps of RAM Commander operation by going through a short tutorial. Upon completing the tutorial, you will be able to do the following:

• Open RAM Commander projects

• Navigate through a product tree

• Generate reliability reports

• Conduct mission profile analysis

• Edit reliability block diagrams

• Conduct maintainability prediction and spare parts evaluation

• Add new projects and components

• View information in the component library

• Calculate reliability for a project

• View and print reports

• Conduct a reliability growth study

• Use the Process/Design FMEA modules.

• Perform FMECA analysis

• Use the Fault Tree Analysis module RAM Commander’s dialog boxes contain many fields. Refer to Appendix A for specific definitions of each RAM Commander field.

Note Complete the installation process described in Chapter 2 before running the tutorial.

62 RAM Commander User’s Guide

Opening a RAM Commander Project Welcome screen (shortcut to recently used projects) The screen below appears after successful login to RAM Commander and helps to quickly navigate to TUTORIAL project, open project list on drive C, open one of 10 most recently used projects, or open RAM Commander Help.

If you do not wish this screen to appear automatically, just check the “Do not show this screen again” checkbox.

To open the Welcome screen manually, select “Welcome screen” from the Drive menu.


If you close “Welcome screen”, your screen will look like this:

To open a RAM Commander project 1 From the Drive menu, choose Open; the Open

Drive dialog box opens.


The Open Drive dialog box displays a list of the drives to which your computer has access.

2 Select the drive where you installed your RAM Commander software.

3 Choose OK.

RAM Commander displays a project view. A project view shows a list of all the RAM Commander projects stored on the selected drive.

If you chose to install the TUTORIAL project during installation, then when you run RAM Commander for the first time, only the TUTORIAL project shows on the installed drive.

Once you open a drive, you can access all the projects to which you have access privileges or permission. (For more information on permission, see Chapter 7.)

On the left side of each row within the project view is a status icon. If the status icon is a green check mark , the item is selected for operations such as copying or deletion. If the select icon is grayed, then the item has not been selected.

To select, deselect, edit or delete items in a project view 1 Click on the row with the right mouse button.

2 In the pop-up menu, choose select, deselect, edit or delete.

RAM Commander toggles the status icon – only for select/deselect, but not for edit/delete.


"Deselect All" option added in Projects list, Library, other lists allows to deselect all marked with the green projects by removing all green " " marks. At the Project List window, from the Project menu, choose “Deselect All” option.

To open the TUTORIAL project 1 Click on the list row containing the project name TUTORIAL.

The row will have a dark gray background.

2 From the Project menu, choose Open - OR - Press F2.

RAM Commander displays the Product tree view. A Product tree view displays all items of a project’s assembly hierarchically.


The Product tree view displays information for each project item:

Field Description

Ref. Des. Reference designator - an identifier you assign to each item

ID Sequential item number within the current assembly - set automatically by RAM Commander

Name Name of item

Qty Quantity of the item in the assembly

Opr. FR[10^-6] Failure rate per million hours in operating mode

Status This field indicates the item’s current status in the project

Customizable Fields in Product Tree View


Now you can change an existing Product tree view by adding new columns. User can create unlimited number of predefined views.

Open project, from the “View” menu choose “Custom Tree fields”.

In Customizable Product Tree View dialog box click on Add button. Add report definition box opens. In Report definition name box type Custom view and choose OK.

After clicking on Add button in the lower part of the Customizable Product Tree View screen Add/Edit Field box opens. Now you can create a new field by selecting required data from Group and Field Name lists. To confirm your selection, click on OK.


In Customizable Product Tree View dialog box click on Close.

In the Product tree view new columns will be displayed.

To select or deselect items in a Product tree view Click on the row with the left mouse button.

Note Use the MS Windows selection convention using the Ctrl and Shift buttons. Only items from one level may be selected together.

To edit, create, insert or delete items in a Product tree view 1 Click on the row with the left mouse button.

2 In the pop-up menu, choose Edit, Create, Insert or Delete.

- OR -

From the Tree menu, choose Edit, Create, Insert or Delete.

Each item within the product tree is associated with a descriptive item icon. These icons follow the RAM Commander conventions for denoting electronic and mechanical components. The assembly icon has a special appearance, and looks like this:


Navigating a RAM Commander Project In this section of the tutorial, you’ll learn how to navigate through a RAM Commander product tree.

If an item in the product tree has a lower level item, then you can review that level in the Product tree view by clicking on the small gray plus (+) sign.

To open a lower level in the product tree 1 Double-click on an item.

-OR-

Click the gray plus (+) sign

RAM Commander displays the lower levels in the Product tree view.

To close a level in the product tree 1 Double-click on an item.

- OR -

Press the gray minus (-) sign

RAM Commander closes the lower levels in the Product tree view previously displayed.


Reports RAM Commander provides a wide variety of reports on product trees, reliability computations, spare parts planning, and much more. Table reports are displayed in report windows with its own report viewer menu and graphs are viewed in dialog boxes. You can customize the appearance of reports using the techniques described in Chapter 11.

You need to select an assembly item that the report/graph will start from.

Tree reports Tree reports provide information pertaining to the product tree. You have wide flexibility in selecting what type of information RAM Commander displays in tree reports.

To view a Tree basic structure report 1 Activate the Tutorial Product tree view.

2 Navigate to any level in the product tree.

3 From the Reports menu, choose Standard Kit; the Report Selection dialog box opens.


4 Select Tree basic structure from the Type list box.

5 Choose OK.

RAM Commander displays the output in a report window. You can print the report by selecting Print from the Report menu or click on the printer icon. The Windows print dialog box opens. Make the selections appropriate for your printer and choose OK.

Repeat the steps of the previous procedure to generate different types of available reports. In step 3, make different selections from the Type list box to familiarize yourself with the various types of reports.

To close a report window, double-click on its control button.

Reports in HTML format (all reports in HTML format, with possibility to export to MS Word and Excel and with easy upload to web)

• New report format allows much more convenient use of RAM Commander reports:

• Select and copy any part of the report • Export tables to MS Excel • Open reports in MS Excel • Open reports in MS Word • Open reports in MS Internet Explorer • Reports are web-ready and can be placed on the web without any

additional conversions. New RAM Commander supports two report formats: RTF and HTML. To switch between the report formats use Reports menu, Setup submenu.

All Product Tree-related reports – maximal depth is increased from 9 to 20

The previous RAM Commander versions had depth limitation of 9 levels. Now you may work with 200-levels deep product tree.


Pareto Reports Pareto reports display the list of components sorted by their contribution to the overall failure rate.

To view a Pareto report 1 Activate the Tutorial Product tree view in Operating.

2 Navigate to any level in the product tree, such as Communic.

3 From the Reports menu, choose Pareto; the Select type of Pareto Report dialog box opens.

4 Select the report type required.

5 Choose Prepare Report.

RAM Commander displays the Pareto analysis report selected.

Repeat the previous procedure to generate different types of Pareto reports. In step 3, select Item Code-Table or Item Code-Graph to view the corresponding Pareto reports. After viewing the reports, close them by double-clicking the control button on their respective windows.


When the Item Code Graph Report is selected, using the new improved Graph Generator for RAM Commander allows you customize the appearance of the Pareto graph by clicking on Setup button, opening Graph Control tabbed dialog box and clicking on respective tab buttons. After selecting required graph appearance (fonts, color, styles etc), click on Apply now button and then on OK.

Click the Clipboard button to export graph to clipboard.

To print the graph, choose Print. The Windows print dialog box opens. Make the selections appropriate for your printer and choose OK.

To close the Graph Generator for RAM Commander dialog box, choose Close.

A sample Pareto analysis


Temperature Curve Reports Temperature curve reports show the influence of temperature on a project’s reliability. You can view the temperature curve results for several environments simultaneously, in graph or text form.

To view a temperature curve report 1 Activate the Tutorial Product tree view.

2 Navigate to any level in the product tree, such as Main Switch.

3 From the Reports menu, choose Temperature Curve; the Temperature Curve dialog box opens.

4 From the Type list box, select Multi Environment.

5 In the Environments list box, select GF, NSB and NUU by clicking on them.

6 In the Description field, type Temperature Report.

7 From the Output list box, select Graph. Your dialog box looks like this:

Like all reports, temperature curve reports are level-specific. See Chapter 11 for more information.


8 Choose OK.

RAM Commander displays a graph similar to that shown below.

Using the new improved Graph Generator for RAM Commander allows you customize the appearance of the graph by clicking on Setup button, opening Graph Control tabbed dialog box and clicking on respective tab sheets. After selecting required graph appearance (fonts, color, styles etc), click on Apply now button and then on OK.

Click the Clipboard button to export graph to clipboard.

To close the Graph Generator for RAM Commander dialog box, choose Close.


Repeat the previous procedure to generate different types of temperature curve reports. In steps 4–6, make different selections in the dialog box to view the different types of reports.

Mission Profile Analysis RAM Commander provides a fast and convenient Mission profile analysis module for product mission, or life cycle, under a sequence of combined environmental and temperature conditions. A specific combination of these factors is called a mission phase. For each product, you define a mission by specifying its various phases.

In this tutorial, you will add a phase to an existing mission profile. See Chapter 12 for information on how to create your own mission profile specifications.

To add a new phase to an existing mission profile 1 Activate the Tutorial Product tree view.

2 From the Modules menu, choose Mission Profile; than Regular MP. The Mission Profile dialog box opens.


This dialog box displays the TEST mission profile. Under the Phase Description column, three stages are listed: Storage, Transportation and Flight.

3 Choose Add Phase. The Mission Profile Phase dialog box opens.

4 In the Phase Description field, type Maintenance.

5 From the Mode list box, select Non-operation Mode.

6 From the Environment list box, select GB.

7 In the Temperature field, enter 20.

8 In the Time field, enter 1.

Your Mission Profile Phase dialog box looks like this:

9 Choose OK.


RAM Commander redisplays the TEST mission profile with the Maintenance phase appearing at the end.

Repeat steps 3–9 in the previous procedure to add more mission phases as you require. When you have completed adding phases, you can view the Mission Profile Analysis Report by choosing Report from the Mission Profile dialog box. RAM Commander displays the Mission Profile Report in a separate window.


Reliability Block Diagrams RAM Commander provides a Reliability Block Diagram (RBD) module to evaluate the reliability, availability and mean time between critical failures (MTBCF) for an arbitrary system. This module also provides a convenient graphic display window to manipulate your system’s structure. It is also fully integrated with the Monte Carlo simulation module.

To load the Tutorial RBD 1 Activate the Tutorial Product tree view.

2 From the Modules menu, choose RBD; the Open RBD dialog box opens.

3 Select STANDARD and choose OK; the RBD window opens.

See Chapter 14 for a description of RBD symbols and display options.


An RBD diagram contains two types of objects:

• a rectangular figure that represents an RBD element; • a small square, called an insertion node, which is used to insert

new RBD elements. There are two types of RBD elements: regular and K-out-of-N. Each element is characterized by a failure distribution and optional repair distribution. You can modify RBD elements to reflect changes in your system.

Improved RBD interface New improved RBD interface allows many new options – customizable fonts and display items for diagram, customizable colors for each element, special symbol of K/N with switch elements, possibility to link each diagram element to product tree element and to its Failure mode from element data dialog:


RBD elements are selected when object sizing handles appear around it, as in the illustration to the right. To select an RBD element, simply click on it.

To modify the Tutorial RBD 1 Select an RBD element, such as “Main Switch”, by clicking on it.

2 From the Item menu, choose Edit - OR - press ALT+ENTER; the Element Parameters Definition dialog box opens.

You can also click the right mouse button to access the Add and Edit menu choices


3 From the Element Type list box, select K out of N.

4 In the N field, enter 10. In the K field, enter 3.

5 In the Repair list box, select Full repair.

6 From the Repair distribution list box, select Exponential.

7 In the MCT [hours] field, enter 10.

8 Choose OK.

RAM Commander updates the RBD diagram:


K-out-of-N model for Sub-RBD The new possibility allows setting a K-out-of-N model for not only a single RBD element, but now also for a Sub-RBD. To use it, choose K-out-of-N on Sub-RBD properties window and enter K and N parameters:

K-out-of-N model with Switch


The new option allows calculation of a K-out-of-N model with Switch. User may set FR distribution model and FR distribution parameters to the switch, and use Monte-Carlo simulation to get RBD results.

To use the option, create K-out-of-N element, enter its data screen, press button “Switch”, and fill data on the Switch data screen:

K-out-of-N items with Switch have a special symbol “S” on their display box in RBD diagram:

RAM Commander has the flexibility to use distributions other than the exponential to characterize RBD elements. The tutorial project comes with a other RBDs, including one called Weibull, which uses the Weibull time-to-failure distribution.

To load the Weibull RBD 1 Activate the Tutorial Product tree view.


2 From the Modules menu, choose RBD; the Open RBD dialog box opens.

3 Select WEIBULL and choose OK; a second RBD window opens with one element.

4 Select the element and right click with the mouse. From the popup menu, choose Edit, or press ALT+ENTER.

RAM Commander displays the following dialog box:

You can modify existing parameters for the Weibull distribution, and then choose OK to close the dialog box. RAM Commander displays the Weibull RBD reliability estimate in the status bar.


Computing the RBD Diagram RAM Commander provides two ways to compute RBD diagrams: analytical and simulation.

Whenever you make a modification to an RBD, the analytical availability and reliability results are automatically recomputed and displayed in the status bar. To initiate an analytical computation of the RBD, choose Analytical from the Calculation menu.

To perform a Monte Carlo simulation, choose Monte Carlo from the Calculation menu. RAM Commander requires some time to run the simulation, after which a table report and graph appear.

The Monte Carlo simulation allows an evaluation of Reliability and Availability for arbitrary configurations when there is no analytical solution. The module allows you to deal with rare events and systems consisting of ultra-reliable and ordinary elements.

RBD steady-state availability and reliability results are displayed in the status bar

Text and graph output from the RBD module


Reliability Function and MTBCF Computations RAM Commander numerically integrates the reliability function R(t) to compute the mean time between critical failures (MTBCF).

To compute MTBCF 1 Activate the RBD dialog box (from the Modules menu, choose

RBD).

2 Choose Standard.

3 From the Calculation menu, choose MTBCF and R(t); the MTBCF dialog box opens.

4 In the field next to Max Time, enter a value of 1000000, step = 100.

5 Choose Calculate; RAM Commander computes the MTBCF and displays the graph of R(t).


6. Choose Close.

RBD MTBCF calculation: support of non-continuous mission Choose “Mission time” option in RBD – MTBCF calculation dialog to get calculation for non-continuous mission:

MTBCF in this case is calculated by formula

)(1

)(

0

0

TR

dttRMTBCF

To

−=∫

,

where To is Mission Time. You can also generate text reports detailing all RBD computations. See Chapter 15 for more information on RBD reliability reports. After completing RBD computations, close all RBD windows by clicking on their control button.

System Configuration This module allows the building of different configurations, where each is a set of assemblies. Different values are calculated for each set: MTBF, MCT, and MTBCF. You can create the configuration based on your project, or create a new configuration from an existing one, or create a custom configuration. The difference between the configurations is in the quantity of assemblies and the reliability models they are associated with (Parallel, Serial, K-out-of-N). This feature allows an easy transformation of the system configuration into the RBD based on the assemblies’ reliability models.

The Tutorial project is supplied with two pre-created system configurations.


To open the configuration system list 1 Activate the Tutorial project.

2 From the Modules menu, choose System Configuration.

3 The System Configuration list opens.

To create a new configuration 1 Right click, and in the pop-up menu, choose New Configuration.

- OR -

From the Configuration menu, choose New.

2 The System Configuration dialog box opens:


3 The calculate button is only activated when an RBD has been

created.

4 Input a new configuration name and relevant data into the other fields.

Inserting assemblies into a configuration 1 Drag and drop an existing assembly (such as Transmitter in the

Tutorial Product tree view) into your new configuration

- OR –

right click the mouse and select Insert from tree.

The Select Tree item dialog box opens:


2 Select the assembly to be inserted and choose OK.

To edit a configuration item 1 Right click on a configuration item, select Edit from the pop-up

menu

- OR -

From the Configuration menu, choose Edit.

2 The System Configuration - Item dialog box opens:


3 Input the relevant data and choose OK.

To create RBD from a configuration 1 Right click on a configuration, select RBD from the pop-up menu

- OR -

From the Configuration menu, choose RBD.

The Open RBD dialog box opens the first time the RBD module is run.

2 See the instructions for RBD manipulation on page 81.

To calculate MTBCF using RBD 1 From the Configuration menu, select Edit

- OR -

Right click and choose Edit from the pop-up menu.

The System Configuration dialog box opens.

2 Choose the Calculate button.

The MTBCF for RBD graph appears (similar to that on page 87).


Preparing a System Configuration report Two report options are provided: Summary and Details.

1 Open a Product tree view.

2 From the Modules menus, select System configuration.

3 Right click on a configuration (such as the Switching base configuration in the Tutorial project) and select Report-Details from the pop-up menu.

- OR -

From the Reports menu, choose Summary or Details.

RAM Commander creates a System Configuration table report.

Note Only a Details report may be selected from the Report-details option on the pop-up menu. For a Summary report, choose the Summary report option from the Reports menu.


Maintainability Prediction To perform maintainability prediction, your project must be in Maintainability mode.

To activate Maintainability mode 1 Activate the Tutorial Product tree view and click on the

Maintainability button in the Current Analysis tool bar.

- OR -

From the Project menu, choose Configuration; the Project Configuration dialog box opens.

2 In the Current Analysis group box, select Maintainability.

Your dialog box now looks like this:


4 Choose OK.

RAM Commander updates the Product tree view to reflect maintainability mode. The quantity and reliability columns are replaced by MTTR (mean time to repair) and Mct (mean corrective time).

The next step in a maintainability analysis is to define the required parameters. In this tutorial, you will modify the parameters for one repair task and then recalculate the project to see how the change affects the MTTR.

To manually edit maintainability parameters 1 Click on the Communic. item and press the plus (+) sign. RAM

Commander displays the assembly’s next lower level.

2 Click on the Main Switch item and from the Tree menu, choose Edit

- OR -

Press ALT+ENTER

- OR -


Right mouse click and select Edit.

The Item Data - Maintainability dialog box opens.

Note The Method of Mct calculation and Method list boxes are already set for the maintainability prediction method. The Level of replace list box displays a value for the replacement level. Make sure that the item’s level of replace matches its parent’s level of repair.

3 Without changing values in other fields, click the MIL 472 Procedure 5A button; the Maintainability-RCM dialog box opens.


4 Click on Disassembly in the Task Type column.

5 Choose Edit.

The Maintainability - Task data box opens.


6 This dialog allows task time selection or calculation. It also contains several additional pages – Skills, STE and Materials. Each one of these pages gives possibility to specify how many and which skilled specialists (Skills), Test Equipment (STE) and which materials like fuel etc. (Materials) is required to perform this task.

7 Change Qty=2 of "T1 standard screws" task to 4 to imulate a longer task duration.

8 Choose OK.


RAM Commander redisplays the Maintainability-MIL 472 procedure 5 dialog box with higher value in the Time column for the Disassembly task. In addition, the values in the Mct and MMH fields are automatically updated.

9 Choose Close.

10 Choose OK in the Item Data - Maintainability dialog box.

You return to the Product tree view. RAM Commander displays the new value for Mct computed in the previous step.

11 From the Calculation menu, choose Quick.

RAM Commander recomputes the MTTR values. Note that the MTTR value for the Main Switch item increases. This result is intuitive: an increase in disassembly time will lead to an increase in required MTTR.

Another way to edit maintainability parameters is to retrieve data from the standard tasks library directly into the Maintainability-MIL 472 procedure 5 dialog box.

To retrieve standard tasks data 1 Click on the Main Switch item and press ALT+ENTER, or right

mouse click and select Edit; the Item Data - Maintainability dialog box opens.

2 Choose the MIL 472 Procedure 5A button; the Maintainability-MIL 472 procedure 5 dialog box opens.

3 Click on Disassembly in the Task Type column.

4 Choose Edit.

5 In the list box next to the Total Time [min] field, select Tasks Library.

6 Make a selection from the Tasks Library list box over the OK and CANCEL buttons. Observe how the value in the Total Time [min] field changes.

7 Choose OK.


RAM Commander redisplays the Maintainability-MIL 472 procedure 5 dialog box. The value in the Time column for the Disassembly task is the last one displayed in the Total Time [min] field in step 5. In addition, the values in the Mct and MMH fields are automatically updated.

8 Choose Close.

9 Choose OK in the Item Data - Maintainability dialog box.

You return to the Product tree view. RAM Commander displays the new value for Mct in the Product tree view.

10 From the Calculation menu, choose Quick; RAM Commander updates and displays the MTTR value.

You can build repair routings (standard task) using standard times. You can then make maintainability predictions as in step 8 of the previous procedure.

For more information on using the Standard Times and Standard Tasks Library, see Chapter 13 – Maintainability Prediction.

Spare Parts Analysis RAM Commander offers a spare parts module to compute safety stocks for spare parts.

To generate a spare parts analysis 1 Activate the Tutorial Product tree view.

2 From the Modules menu, choose Spare Parts.

3 Select Quick Calculation or Optimization and their respective dialog boxes appear.

Quick Spare Calculation 1 In the Quick Spare Calculation dialog box review scenario

parameters and then choose the Calculate button.


In the Spare parts - Report Options dialog box, select the Intermediate and Depot check boxes.


RAM Commander displays the results of a spare parts analysis in a report window.


You can change the report parameters to reflect your system scenario. See Chapter 17 for more information on building spare parts scenarios.

ISLE Spare Optimization Calculation 1 Activate the Tutorial Product tree view.

2 From the Modules menu, choose Spare Parts.

3 Select Optimization.

The ISLE - Spare Optimization dialog boxes appears.


Review the scenario parameters. In addition to the previous option there are additional optimization parameters.

3 Enter Budget.

4 In the ISLE - Spare Optimization dialog box choose the Optimize button and the Spare parts - Report Options dialog box opens.


5 In the Spare parts - Report Options dialog box, select the

Organizational check box.


RAM Commander generates a Cost Optimization graph in a graph window and a Spare Parts Optimization table report.

The report parameters may be changed to reflect your system scenario. See Chapter 17 for more information on building spare parts scenarios.


Adding a New Project When you add a new project, your first step is to create and define it.

To create a new project 1 Activate the Project list.

2 From the Project menu, choose Create or press F7. The Edit Project Properties dialog box opens.

3 In the Project Name field, type a word such as FIRST.

4 Tab to the Description field and type a description such as Sample project for the tutorial.

Your screen now looks like this:

5 Choose OK.


RAM Commander updates the project listing on your disk drive.

Your next step is to open the project so that you can start to define it. Press F2; an empty Product tree view opens.

Now assign a prediction method for the project’s electronic, mechanical and electro-mechanical components. From the Project menu choose Configuration. In the Project Configuration dialog box, make the following selections.

From this list box make this selection Electronic MIL-217F-2 P. stress

Mechanical NPRD-95

Electromechanical NPRD-95


When you have finished making the selections, your dialog box looks like this:

Choose OK; RAM Commander returns you to the Product tree view.

Adding New Assemblies Product trees are typically constructed of several assemblies that in turn are constructed of components.

To add a new assembly 1 With the Product tree view activated, from the Tree menu, choose

Create


- OR -

right mouse click and select Create from the pop-up menu

- OR -

Press F7; the Item Data - Operating dialog box opens.

2 Tab to the Ref. Des. field. Type PS.

3 Tab to the Part Name field. Type Power Supply. Your screen now looks like this:


4 Choose OK.

5 Repeat steps 2–5, except this time type PC for reference designator and Personal Computer for part name.

6 Choose OK.


You return to the RAM Commander Product tree view, which now looks like this:

You now have a product called FIRST with two subassemblies, PS and PC.

Adding New Components Components may now be added to each subassembly.

Adding a component - Phase 1 1 Select the PS subassembly by clicking on it.

2 From the Tree menu, choose Edit

- OR -

Right-click the mouse and select Edit from the pop-up menu

- OR -

Press ALT+ENTER

The Item Data - Operating dialog box opens.


3 From the Family list box, select ELECTRONIC.

4 From the Item Code list box, select IC-Digital.

5 In the Ref. Des. field, type U1.

The top of the dialog box now looks like this:

6 Choose the MIL-217F-1 P.stress button.

RAM Commander opens a dialog box titled IC Digital MIL-HDBK-217FN1.


This dialog box contains the detailed reliability information needed for reliability prediction.

Adding a component - Phase 2 1 From the Type list box in the IC Digital

MIL-HDBK-217FN1 dialog box, select Gate/Logic Arrays.


2 Toggle the defaults for gate/logic arrays by choosing the default icon.

3 Choose OK and then choose OK in the Item data – Operating dialog box. You return to the Product tree view.

Repeat steps 3–7 of phase 1 and steps 1–3 of phase 2 to add another component to the PS assembly. This time, select Resistor from the Item code list box, and type R1 in the reference designator field for phase 1; in phase 2, select RC from the Style of Resistor list box. Choose OK.

Your Product tree view now looks like this:

Next, add components to the second subassembly, PC.

Select the PC and repeat steps 3–7 (phase 1) on page 111 and 1–3 (phase 2) above. Use the following table for family, item code and reference designator fields.


Part Family Item code Ref. Des.

1 Electronic Capacitor C1

2 Electronic Connector P1 Select Power in Configuration field

This completes the data entry phase of your project. At this point, you may perform a quick reliability computation by choosing Quick from the Calculation menu.

Using NPRD as a Reliability Prediction Method

RAM Commander supports the NPRD reliability prediction method for mechanical and other non-electronic parts. In this tutorial, you will add a mechanical component to the project and estimate its NPRD reliability values.

To add an NPRD mechanical component to the tutorial project 1 Activate the Tutorial Product tree view.

2 Navigate to any level.

3 Press F7 to create a new item.

4 In the Item Data - Operating dialog box, select Mechanical in the Family list box.

5 Select Battery from the Item Code list box.


6 Type a reference designator, such as Battery, in the Ref. Des. field.

The dialog box looks like this:


7 Click on the NPRD-95 button to the right of the dialog box; the battery’s NPRD dialog box opens.

8 From the Part Description list box in the Primary choice group,

select General. In the Search data for calculation by list box, select Primary/Secondary.

9 In the Quality list box, select Unk (unknown).

RAM Commander performs a search in the NPRD database and displays the certainty value in the failure rate field. Again, from the Quality list box, select Mil (military). RAM Commander searches the NPRD database and displays a different certainty value in the Failure rate field.


10 Choose OK and choose OK in the Item data – operating dialog box.

RAM Commander displays the certainty value under the FR column of the Product tree view.

RAM Commander searches the NPRD library for the battery’s failure rate first using the primary General description, and then the secondary Summary description.

Failure Rate Table Libraries RAM Commander provides a special library for field reliability data. You can apply the values in the library to perform reliability prediction and analysis.

In this tutorial, you will create a new failure table using manual data entry.

To manually create a new failure rate table 1 Activate the Product tree view.

2 From the Library menu, choose GPRD; the Table Manager dialog box opens.


3 Choose Add; the Add/Copy Table dialog box opens.

4 In the Add/Copy Table dialog box, enter a Part name, such as

HARD DISK, and select GB from the Environment list box.

5 Choose OK.

6 In the Table Manager dialog box, click on 35 in the Temperature column.

7 Choose Edit.


8 In the FR Table Data dialog box, enter a failure rate in the F.R. field.

9 Choose OK.

10 Repeat steps 5–6 to enter several other temperature values and failure rates. As you make new entries in the failure table, RAM Commander redraws the failure rate graph.

11 In the Table Manager dialog box, choose Close.

The new table is now available for use during reliability prediction.

By checking “Use for conversion” check box, you can mark one of the environments as “Use for conversion”. This table is now for a specified environment and is set as the default for the specified Part Name. If you try to perform calculation for this part name and for other environments, which do not have FR Table data, the program will take the default environment for this part name.

Reports To generate reports for the failure rate table library, open the Table Manager dialog box. In the Request group box to the right of the dialog box, select one of the following:

All to generate a report for all part names and all environments

Part Name to generate a report for the selected part name

Environment to generate a report for the selected environment

RAM Commander displays the report in a separate window. After viewing the report, press CTRL+F4 to close the report window.


Applying Failure Rate Tables RAM Commander uses the part name, environment and temperature values in the Item Data dialog box to extract an item’s failure rate from an FR table.

To apply a failure rate table to a product tree item 1 Highlight an item in the Product tree view and press ALT+ENTER;

the Item Data - Operating dialog box opens.

2 In the Part Name field, enter the name of the table used in step 4 of the previous procedure.

3 In the Environment field, select GB.

4 In the Method of Lp calculation list box, select user defined.

5 In the Method list box, select Table/Packed project.

6 Choose the Table/Packet project button, the Table Manager dialog box opens.

RAM Commander displays the Table Manager dialog box, similar to the one on page 118. Choose Close to close the Table Manager dialog box; choose OK to close the Item Data - Operating dialog box. RAM Commander displays the Product tree view. The failure rate for the highlighted part is what was specified in step 6 of the previous procedure.

Calculating Reliability The reliability of the subassemblies may now be calculated. From the Calculation menu, choose Quick. RAM Commander updates the numbers in the Opr. FR (operating failure rate) column.

Now you can generate a report for screen display and printer output. Follow the procedure on page 70.


Reliability Growth RAM Commander supports the Duane reliability growth model described in MIL-STD-1635.

To view the reliability growth window 1 Activate the Tutorial Product tree view.

2 Verify that the Operating mode is selected in the Current Analysis group in the Project Configuration dialog box (see page 94).

3 From the Modules window, choose Reliability growth; the Reliability Growth list opens.

RAM Commander’s Reliability Growth module allows you wide flexibility in defining the growth parameters. See Chapter 20 for more information on customizing Reliability Growth models.

When the reliability growth list is displayed, you can generate text and graph reports.


To generate Reliability Growth reports 1 With the Reliability Growth list activated, from the Reports menu,

choose RG Info; the Reliability Growth report dialog box opens.

2 Choose OK.

RAM Commander displays a reliability growth report in table form.


To generate a reliability growth report in graph form, repeat the previous procedure. This time, select Graph in the Type field. After choosing OK, RAM Commander displays the same report in graph form.


Use the techniques described in Chapter 20 to set reliability growth parameters


Process/Design FMEA In this section you will go through the basic steps of performing an actual Process/Design FMEA study. The Tutorial project supplied with our installation set presents the example supplied with the PFMEA module but you can similarly work in the DFMEA module.

The example presents a simplified Process of printed circuit board production. The diagram presents each step of the process as a diagram item. FMEA will deal with the potential Failures on every step of the process.

Process / Design FMEA Main View To enter Process/Design FMEA main project window. 1 Click Modules on the left toolbar of the RAM Commander

Product tree view

- OR -

From the Modules menu, choose Process FMEA or Design FMEA

The FMEA screen consists of two parts – the flow diagram in the upper part of the window and a data table in the lower part.


The flow diagram presents each step of the process as a diagram item.

Process / Product Flow Diagram Let’s learn the basics about FMEA flow diagram building and manipulation. An accurate and easy to understand diagram of your process/product is a very effective tool for presenting your FMEA project.

To view / insert / edit a diagram item 1 Select the Print board node on the diagram by clicking on it.

2 Change the size and position of the item by moving it and pulling its placeholder handles with your mouse.


3 Double click on the item.

The FMEA item data dialog box opens.

4 Choose the Color button. Select any color you wish and choose

OK.

5 Select a shape from the Shape drop-down list.

6 Select text alignment in Alignment list. Select the text font by clicking on Font button.

7 Choose OK to see the changes applied to the item.

Failure Mode, Causes and Effects Data The lower part of the main FMEA main window serves for the input and presentation of all intrinsic components of FMEA: failure modes,


causes, effects, severity, occurrence, detection, controls, corrective actions and recommendations.

Let’s learn how to work with the table displaying this data.

To view and understand the FMEA data of a diagram item (process step or product element) 1 Select the Prepare laminate item of the diagram by clicking on it.

2 The FMEA data for this process step is displayed in the lower part of the screen.

Note See Chapter 19 for a detailed description of the PROCESS/DESIGN FMEA fields

The first three columns present the Potential Failure Modes of the selected step of a process. The other columns are: Causes of the Failure, occurrence, current process controls, detection, RPN, recommended actions, taken action, result occ., result det. and result RPN. Each process/part may have an unlimited number of failure modes, and each failure mode may have an unlimited number of corresponding causes of the failure. Move the horizontal and vertical scroll bars to view all the data in the table.

To view / edit a failure mode 1 Click on the first line of the table, right-click and choose Edit FM.


The Insert/Update Potential Failure Mode dialog box opens:

Here are the descriptions of possible failures, the effect of the failure and the severity. All the fields can be edited directly in this dialog (try to place the cursor in the Effect of Failure field and type some text) or from the library.

To enter the library 1 Press the button “>” to the right of the Effect of Failure field.

The Select Severity dialog box opens.

2 Choose the line in the library required and press Select.

3 To store the Failure data in the table, choose OK in the Insert/Update Potential Failure Mode dialog box.

To view / edit a Potential Cause of Failure 1 Click on the data cell in the fourth column (Cause data).

2 Right-click on it and choose Edit Cause from the pop-up menu.

The Insert/Update Potential Cause of Failure dialog box opens with possible failure cause information.


You can change all the data directly on the screen, or call the library by clicking on the “>” button.

Here you can see the description of the possible cause, quantitative characteristics of it, the Control Method of the Cause (a method which can be used to detect the cause), and a description of actions taken to prevent the failure.

To the right of the Actions field, you can see new values of Detection and Occurrence. These values are improved values of Cause occurrence and Control method detection, after the corrected actions were (will be) performed. The resulting RPN must be less than the initial value – the goal of the FMEA analysis is to reduce risk and increase reliability.


Decision Making The Decision Making utility, accessed from Include/Update Cause Information dialog box, is a special utility designed to track alternative methods of preventing failure causes, to analyze possible corrective actions and to choose the best implementation from among them.

1 Open the Insert/Update Potential Cause of Failure dialog box.

2 Press the Decision Making button to open the Corrective Actions – Decision Making dialog box.

Here is a list of all possible recommended actions that can help to correct the problem. You can write down the advantages, disadvantages and remarks, etc. for each action. During the process of


discussion, analysis or testing, we can calculate which actions in the list are valuable and helpful, and which are not. Those actions we choose to perform are marked green and called “Selected actions”. Performed actions are called “Taken Actions”. You can select or deselect an action in the list by clicking the action and pressing the Select and Deselect buttons beneath the table.

3 To close the dialog box, choose OK.

The primary advantage of the Decision Making feature is that you can maintain a list of all recommended actions for preventing a failure cause. If the action you adopt isn’t successful, you’ll have a record of other candidate actions ready for implementation.

The new feature gives possibility to work with all selected corrective actions, concentrated in one data table:

Select “Actions Data Table” from the Item menu of FMEA module to use this feature.


FMEA – Multi-user mode

RAM Commander allows multiple users to edit the same FMEA analysis case. Only one (first) of the users has exclusive access to diagram itself (picture elements, their position, colors etc.), but all users have a free access to FMEA data (analysis table in the lower part of the screen).

Managing Process/Design FMEA Libraries Process/Design FMEA’s set of libraries provides a convenient facility to quickly and efficiently build and update projects. The libraries contain predefined data for FMEA analysis. You can modify the data in the libraries as required.

Below you will learn how to access Process/Design FMEA libraries. The effective use of these libraries ensures that the time you spend with Process/Design FMEA will produce quick and accurate results.

To access the libraries 1 Activate the Tutorial project and open a Product tree view.

2 At the bottom of the tool bar, click on the Modules button

3 Select Process FMEA.

- OR -

From the Modules menu, choose Process FMEA

The Process FMEA for Project Tutorial window opens.

4 Select a diagram in the upper window.

5 From the Libraries menu, select the required library.

The Library window opens (e.g. Occurrence).


The following buttons are available:

Add – To add a library item.

Edit – To edit the highlighted item.

Delete – To delete the highlighted item.

Print – To print out the library item list.

Close – To close the window.

To modify / add / delete data in a library • Select a row to be modified and click on the Edit button.

• Click on the Add button to add a row to the library.

• Select a row to be deleted and click on the Delete button.


Process/Design FMEA Reports Reporting Process/Design FMEA provides a number of standard and additional reports. To review the available report groups, select the Reports option on the menu bar; the Process/Design FMEA Report menu appears. To review all available reports in each group, choose the corresponding option from the Reports menu, or click on one of the four report icons to open the corresponding report parameters dialog box.

To generate FMEA reports 1 From the Reports menu, choose FMEA reports.

The FMEA report generation dialog box will open with a list of reports and some radio buttons to choose from:

Sort the report – by RPN, by Resulting RPN, or no sorting.

Contents of the reports – all the processes/design elements, or selected diagram elements only (see Diagram Basics – Multiselection topic) or all elements and Sub-FMEA (get not only the currently open FMEA data, but also all child Sub-FMEA diagrams data).


2 Choose the report you need (e.g. “FMEA Standard”), choose report sorting and limits (all/selected elements) and choose OK.

After a brief data processing procedure, Process/Design FMEA displays the report in a window. Use the scroll bars to view the entire report. To print the report, from the File menu, choose Print.


To change default report parameters

See Chapter 11 on how to change the default report parameters

Diagram Modification

Adding a new item

Now, let’s modify the diagram. We will create a new diagram element – Quality Control, between the elements External Connection and End.


Choose a free space on the diagram, click on it and move the mouse pointer to draw a rectangle. Release the mouse button.

-OR-

Right-click on the empty space of diagram and choose “Create” from the popup menu.

An item will be created and you will see the item data screen. Enter the name - Quality Control, change the other data, choose the shape and color of the new item:

You should get something like this:


Click the link between the elements External Connection and End, press the Del key, then choose OK to delete the link. Move End to the right, into the free space for the new item. Move the new Quality Control item between External Connection and End.

Now let’s draw links. Click External connection. You will see a placeholder (small black square) in the center of the item. Drag it, pull and drop it to the new item. Release the mouse. Repeat the operations to create a link between the new item and End.

We have created a new item in the diagram, but it does not look pretty enough. The items are of different sizes, their vertical positions differ, that’s why the links are not straight.

Let’s correct it.

Select the items: click on the left-most item (it will be a sample for size and position), press Ctrl and hold it while clicking on the other 2 items. Placeholders should appear around all of them.

From the Item menu, choose Make same size and then Align top edges. We will obtain the following result.


Now, let’s perform an FMEA analysis on this particular process step. For example, quality control for board production is performed by a robot. The robot could have a general operation failure due to power loss or internal errors. Thus, the robot could fail to remove bad products from the production line – for example, due to a lack of storage space for bad products.

Let us write data into the table.

Select the Quality Control item. The lower table should be empty.

First right-click on the cell in the table and choose Add FM from the pop-up menu. Fill in Failure data and choose OK:

Right-click on the newly created line and choose Add Cause. Fill in Cause data and press OK.


Once more select the line, right-click on it, choose Add Cause from the pop-up menu and fill in the data for the next cause: Quality Control robot internal errors, Control method – Visual inspection, movement detectors. Choose OK.

You will obtain the following table:

Let’s think how we could improve the situation with the failure. In the case of a power failure, possible actions could be: a) Stop production line automatically if the power is off to the quality control robot; b) Provide the robot with accumulators; c) Entrust the quality control task to humans. Let’s enter the data into the system.


Select the first line of the table (cause: power loss), scroll to the field “Recommended actions”, and press the <….> button. You will be in Decision making mode.

Press the New button beneath the table and enter data for a new possible corrective action and choose OK.

If you want to store the action in the library for future use, click on the Add to library button. If you want to take an action from the library, you can press the Select from library button.


Enter two other actions, and you will get the following table:

Now you can weight all the advantages and disadvantages, perform an analysis and make a decision as to which of the actions are worth being implemented. For example, you could choose the first and the third actions. Click on the first action and press the Select button. Click the third action and press the Select button. The selected actions will be highlighted in green.

Now, these actions serve to reduce risk, to decrease failure cause occurrences or to improve the detection-ability of the failure (decrease detection rank). You can set new values (or new forecast values) for Occurrence or Detection throughout the table:

After implementing the action, you can enter action progress for every action, and fill in the “Actions Taken” field. If the real Occurrence or Detection after implementation differs from your initial forecast for recommended actions, you can change them:


Choose OK to return to the main FMEA screen.

The FMEA table for the new item should look like this:

The field “Recommended action” contains all the actions you entered, but selected actions are marked with a “>” sign in front of it. “Taken Actions” and resulting Occurrence and Detection values can be changed in this grid too.


To print an FMEA table for this new item only, select the item in the diagram, then from the Reports menu, choose FMEA reports. In the reports list, choose FMEA, and click the Selected elements only radio button. Choose OK to print a report.

Summary Upon completing this tutorial, you will have:

• gained the skills required to perform almost all types of RAM Commander reliability and maintainability analyses. The remaining material in the User’s Guide provides greater detail of the RAM Commander functions.

• learned how to modify an item's data within the tree, and how to approve an item’s data changes.

• learned Process/Design FMEA basics: building libraries, modifying the FMEA tree, data checking and generating output reports.

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