Related Topics:
	FMEA Records

Causes

Causes are FMEA records that state the specific reason for the failure, preferably found by asking "why" until the root cause is determined. Some of the features for working with causes will depend on the FMEA structure that has been selected for the current project.

The following topics are discussed here:

• FMEA Structure and Causes

• Adding and inserting causes

• Editing causes

• Copying and pasting causes

• Cause properties

FMEA Structure and Effects

As discussed in Choosing the FMEA Structure, you can use the FMEA Structure field on the General page of the Project Properties window to choose how you want to display effect and cause records in the FMEA hierarchy. Note the following:

• If the FMEA structure is Causes Before Effects or Grouped Effects and Causes, each cause will be associated with a failure record.

• If the FMEA structure is Effects Before Causes, the cause will be associated with an effect record.

Adding and Inserting Causes

To add or insert causes into an FMEA, select the failure or effect that the cause will be associated with and choose FMEA > FMEA Records > Causes, then select one of the following options:

  Add Cause adds a new record to the bottom of the list.

  Insert Cause inserts a new cause above the one that is currently selected.

  Import Causes opens the Import Existing Causes window so you can choose to copy one or more of the existing causes into this FMEA. There is no link to the original record(s) (i.e., changes made in one record will not automatically update the other(s)), and you have the choice to import with or without dependents (e.g., associated effects, causes, etc.).

Editing Causes

To edit an existing cause in the project, either edit it directly in the worksheet view or use the properties window. To open the properties window, select the cause and choose FMEA > FMEA Records > Causes > Edit Cause or double-click the cause in the hierarchy or filtered view.

Copying and Pasting Causes

If you have copied a cause, there are two options when you choose Home > Clipboard > Paste:

  Paste (CTRL+V) pastes the cause(s) and all dependent records (e.g., controls, actions, etc.).

   Paste Without Dependents pastes only the cause(s) without any dependent records.

Cause Properties

Note the following:

• The Cause Description is required.

• Use Classification to identify design characteristics that require special manufacturing control (e.g., Critical, Significant, Key Leading, etc.).

• The options in the following drop-down lists are based on the occurrence scale that has been assigned in the Project Properties window. The RPN will be calculated automatically if you have defined a Severity rating for the effect, and Occurrence and Detection ratings for the cause.

• • The Initial Occurrence and Revised Occurrence ratings are numerical values that estimate the probability of occurrence for the potential failure cause.

  • The Initial Detection and Revised Detection ratings are numerical values that estimate the probability that the problem will be detected before it reaches the customer or end user.

Tip: If you need to define the reliability characteristics for this record, use the FMRA tab. These characteristics will be applicable if you wish to perform criticality analysis, use the FMEA occurrence ratings to calculate a preliminary baseline estimate of the system reliability or share system configuration/reliability data between Xfmea and BlockSim.

What's Changed? In previous versions of Xfmea, the probability of occurrence for the cause was set using the Probability of Occurrence page of the Cause Properties window. In the Synthesis version, the probability of occurrence for the cause is defined by setting the cause's universal reliability definition (URD) in the new FMRA tab.