FMEA Worksheet

Worksheet 41. FMEA Worksheet

General Information

Function Potential Potential

Potential Current

Recommended Responsibility

Actions

Failure Failure

Causes

Controls

C Action

and Due Date

Taken

Mode Effect

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Issue#

Process Metrics

Six Sigma projects operate upon business processes. These processes are designed to deliver something of value to a customer, such as a product or a service. For this reason, these processes are sometimes called customer value streams. The purpose of most Six Sigma projects is to improve business processes so that they deliver greater value to customers. In this section you will determine precisely how the success of these efforts will be measured.

What Are the Key Metrics for This Business Process? Six Sigma process metrics typically fall into one of three major categories: quality, cost,

or schedule. These characteristics are critical to the success of the enterprise and are thus commonly referred to as “critical to” characteristics. A critical-to-quality characteristic (CTQ) is one that impacts on the fitness for use of the product or service produced by the process. A critical-to-cost (CTC) characteristic has a significant impact on the cost to produce the product or service. A critical-to-schedule (CTS) characteristic has a significant impact on the ability to deliver the product or service in a timely manner. Collectively, these are often called CTx characteristics, where x = Q for quality,

C for cost, and S for schedule. Note that it is often difficult to separate a metric into one and only one category. For

example, if a Six Sigma project involved a coffee mug manufacturing process, a crack in

a coffee mug would be classified as a CTQ characteristic even though cracked mugs also impact cost and schedule. Normally, the CTx is assigned to the dominant effect; in this case it is quality. An example of a CTC characteristic for the coffee mug process might

be the energy consumed firing the ceramic. A CTS characteristic might be the timeliness of raw material deliveries.

DPMO Definition Defects-per-million-opportunities (DPMO) criteria must be carefully defined. The defect

must be described in clear, rigorous, and unambiguous terms. Defect definition often includes photos, physical specimens, or other inspection aids. Similar attention must be given to the opportunity used as the base. Opportunities are events or characteristics that might be incorrect.

Example: Wave solder. A defect would be an improperly produced solder joint. The defect might be missing solder, incomplete solder, poor solder bond, grainy solder, short circuits, etc. Each of these defects would be carefully defined and personnel would be thoroughly trained to identify each. A single solder joint might have several defects; all would be counted. The opportunities would be solder joints. DPMO would

be calculated for this process as follows:

defects

DPMO = 1, 000, 000 (Equation 1)

number of solder joints

For example, for a circuit board with 1,000 solder joints and 5 defects, the DPMO would be:

The DPMO for a characteristic is measured as the process average DPMO. Poorly chosen opportunity metrics can lead to “denominator management”—

manipulation of the measurement system. For example, the opportunity metric for complete electronic units delivered to final assembly should be the number of units, not the number of solder joints in the units. A proper denominator reflects the process being measured, not an earlier process or subprocess. For example, if the process is creating solder joints, then solder joints are a proper opportunity measure. If the process is placing circuit boards into an electronics assembly, then we would count circuit boards, connectors, fasteners, etc. but not the constituent elements of these parts.

If you find that games are being played with the measurement system, list it as an issue to be resolved by the project sponsor, process owner, or management. If the issue is serious enough, consider classifying the project as “Stalled” until it is resolved. Six Sigma can’t function in an environment where honest measurements are not available.