Methods for Making the System Definition Process Easier

When performing reliability prediction analyses to compute MTBF (Mean Time Between Failures) parameters, the data entry portion can be the longest part of the process. First, the system hierarchy must be defined. The system hierarchy is generally made up of multiple assemblies, with each assembly having its own parts list. To accurately predict your system MTBF, each of these components must be logged and categorized. Component lists can be long, and the entry of all the parts and their associated data parameters can be tedious and error prone. This article describes some methods for making this process more efficient, resulting in better predictions in less time.

Importing

One method commonly employed to speed up the data entry process for MTBF analysis is to import BOM (Bill of Material) files rather than to manually enter each part one record at a time. Pictured below is an example of a BOM. A BOM stores the part lists for the assemblies in your system. Being able to import a BOM into a reliability prediction software package is more efficient and less error-prone than the manual entry of part data.

Sample BOM

In the above BOM, a text file contains a parts list with specific part information. In this text file, commas are used to separate the various data elements. Thus, it is called a delimited text file. The commas signify where one column of data is to end and another column of data is to begin.

The information in a BOM can be imported into a reliability prediction software package. This process takes the information in a delimited text file or from a table in such applications as Microsoft Excel or Access and copies it into the appropriate fields in the software package. When importing, you must map the part data in the BOM to the appropriate fields. Mapping consists of telling the software package if the information in the BOM is being viewed correctly and specifying how this data is to be stored in the database.

Mapping the Part Data in the BOM

The above figure shows how the data in a BOM might be mapped for importing. The delimited text in the BOM is broken into columns, depending on where the comma delimiters are placed. When importing part data from a BOM in either an Excel or Access file, the columns in that table are used. To map the part data in the BOM to the fields in the software package, for each column, you choose the field into which the data in that column is to be copied. If you do not want to import a particular data element in the BOM, you simply do not map it, and it will simply be ignored during the data import.

Automating the Import Process

At times, the mapping of data for the import process can be very lengthy. The number of data elements in the BOM can be very large, and mapping the columns to fields in the software package can be time-consuming and potentially hazardous. In these cases, the import process can be taken one step further by automating the mapping process. This is accomplished by saving mapping information to a file for later reuse. If you can save mapping information to a file, whenever you have a new BOM that is set up in the same manner, you can use the saved data mapping information to automatically map the fields, both expediting the import and minimizing opportunities for mistakes to occur.

Part Libraries

Another technique to make part entry more efficient is to use Part Library data files. Part Libraries store part numbers and the specific data associated with these parts. When a part number is entered, these libraries are searched to see if a part number mach is found. If a match is found, then all of the specific data for that component is automatically retrieved.

Part Libraries are also used during the importing of part data to even further expedite the data entry process. When the mapping of the part data in the BOM occurs, one of the data elements is likely to be the part number. When the part number is included in the import process, the Part Libraries can be searched for part number matches in the same manner as if they were manually entered. Once again, if the part number is located in the Part Libraries, all the part data is automatically retrieved.

Consulting Services

Lastly, in some cases, it makes more business sense to offload the data entry and data parameter look-up to an outside service adept at doing this type of work. Additionally, the resources needed to perform reliability predictions are not always available in-house at the time such analyses must be completed. In these cases, the Relex Consulting Services team can help you out.

Relex consultants are experienced reliability professionals, many with Certified Reliability Engineer credentials from the American Society for Quality and/or advanced degrees in reliability engineering. Every day, they work with reliability and quality professionals in diverse industries such as automotive, aerospace, defense, information technology, medical, process control, and telecommunications. The Relex Software consultants have helped a large number of customers in a wide array of industries in their MTBF analysis work.

Using industry standard best practices, Relex consultants can provide you with the knowledge and experience needed to maximize the benefits derived from your reliability program. For example, when time is a constraint, they can serve as an adjunct to your reliability team, doing anything from creating a custom Parts Libraries to performing all of the types of reliability analyses that you need. You can learn more about our consulting services by visiting www.relex.com/services/consulting.asp.

Summary

Accurate MTBF analyses require gathering a comprehensive list of all components in the system. Even though the number of parts may be great in large systems, if an efficient mechanism is in place for easily entering and reusing part data, this task can be streamlined. Relex Software's MTBF tools, including Reliability Prediction, provide various methods to help with this effort. For additional information about the many reliability analysis tools in the Relex Reliability Software Suite, visit our web site.