Yield Rate: The Daily Definition
What is yield rate?
Yield rate (in this case the first time yield or FTY) is the expected success rate in the manufacturing process for an item. Manufacturers calculate their yield by dividing the number of “good” units by the total number units that went through the process. Only good units with no rework or scrap are counted as part of this calculation— any goods that don’t meet a defined standard are either discarded or reworked. Total process yield considers only what went into a process step and what went out, but the FTY helps identify waste in your operations.
Yield = the number of non-defective items / the number of manufactured items
On a production line, if 100 units go in and 90 make it out, the yield rate is .9, or 90%. This is straightforward enough, but what if you have multiple steps in production? To determine the overall FTY of your entire manufacturing process, multiple the yield rate of each step together.
Using a three-part manufacturing process, calculating the FTY looks like this. Say the yield of step one is .92, the yield of step two is .9, and the yield of step three is .7. To determine the first time yield of the entire process, multiply .9 x .875 x .7. The total yield rate in this case equals roughly .58.
Our two cents:
Identify the yield rate of your production to see where you’re experiencing inefficiencies. From our example above, the rates for steps one and two are OK, if not a little low, while step three deserves a closer look. Maybe there’s a defect in some machinery on this step, or possibly a technician working on this line needs a little more training.
While FTY is a useful calculation for identifying gaps in your efficiency, don’t cling to it as the only form of yield rate that can be used. Rolled throughput yield and traditional yield are both useful methods for further streamlining your operations.