With these figures, it is possible to go to data for similar production efforts and determine actual yields that can be compared to the new project.
If it is found that yields similar to the component's 99.32% have been achieved previously, then a 'bid' decision, if that is the issue, can be supported.
If the data on past experiences show that producibility of some elements or components did not achieve the yields necessary to reach the specified goal, then a degree of risk enters into the producibility measurement.
If the disparity is small, it might be overcome by changing suppliers or materials being used or making an improvement in the production process.
If the disparity is large, perhaps a design change in the board is dictated - maybe the total number of elements can be reduced from six to four or the components from four to three or two, thus reducing potential misplacements in assembly, the frequency of soldering errors, and failure rates.
If there is a truly large gap, it is the responsibility of management to seriously consider dropping pursuit of the program or for the DoD customer to review its specifications or consider other sources.
In all instances, if complete data are not available for all the components involved, educated estimates based on the best data available and experience can be used. But, the more estimates and incomplete data are used, the greater the risk involved in the measurement that is rendered and any decisions that may be based upon that measurement.
What has been depicted above is a simple example of
Measurement Tool 2
can be used deductively - to determine what is needed to achieve a customer or company-specified goal. The depth of the measurement can be broken out to further suballocate yield to lower levels, depending upon the size of the potential contract, the nearness to the goal achieved at any given level, the amount of risk the company or the DoD customer is willing to accept, etc.
Even when this form of producibility measurement indicates that the aggregate yield for all components is sufficient to meet the overall design goal, it may highlight weaknesses that can be reduced or eliminated to improve quality and producibility for the benefit of the company and DoD.
For example, if 18 of the 24 components on our original board had high enough yields to offset somewhat lower yields of the other components and allow the board to achieve its 85% goal, it would be good business to explore how the yield of the substandard components might be improved and how such an improvement could positively affect quality and profitability.
It might be that using a 25-cent resistor instead of a 15-cent resistor would do the trick and produce a rework savings of $1 per board. On the other hand, if it is necessary to replace the 15-cent resistor with a $1.50 resistor to save $1 of rework, the cost of improved producibility is not justified.
Tool 2 can also be used by reversing the mathematical process, moving from components to elements to boards, etc., to determine the overall producibility of a product so management can determine if it is economically feasible with the manufacturing resources available. This approach can be used most effectively when historical yield data are available.
It can also be used to identify areas where quality and productivity can be improved to increase profitability for the contractor and to
provide the DoD customer with a product that has increased reliability, maintainability, and operability at lower cost.
Measurement Tool 2
is used, its primary goal is to eliminate or reduce observed or potential defects in design, process, and materials to achieve increased producibility.
Producibility Measurement . . .
whether Tool 1, 2, or both are used, is not something that is done once and then forgotten. It should be a continuous process repeated frequently in the early stages of a program, where new data emerge almost daily and variables are most likely to occur, and periodically as a program matures to ensure that the most cost effective methods of production are being maintained.
of the basis for Producibility Tools 1
& 2 can be found in the first three works listed in the bibliography that