Key Points

• FTY is a calculation for determining how a product goes through a process without any defects showing up.
• This calculation is quick to do, allowing for rapid changes if needed.
• It is one of the most important tools at your disposal for discovering defects or flaws in your processes.

The purchasing department manager left another message, informing the planning department that they once again sent over a request for a quote that didn’t contain all the information needed to place the order. 

It’s a problem that seems to keep repeating, but is it truly that impactful an issue? To better understand the situation, the true frequency of the problem must be quantified, and that’s where first-time yield is used. 

An Overview: What Is First-time Yield?

First-time yield, also known as first-pass yield, is the percentage of the time that a product or service passes through a process step without any defects on the first attempt.

The formula is straightforward, being the number of products that pass through a step of the process without error on the first attempt, divided by the total number of products being tested. Be sure to recognize that the total number of products is different than the total number of tests run. This can be true if a single product may be tested multiple times if rework is involved.

First Time Yield = [Number of products without error / Total number of products]

For example, the planning department creates 20 quote request documents. These documents are required by the purchasing department as they contain key information needed to reach out to the suppliers and acquire a quote. 

It turns out that four of the requests contain incorrect data. They require the purchasing department to return the documents back to the planning department for rework. Sixteen quote request documents have correct information the first time they pass through the step. Using the formula, we take the 16 documents that passed the first time and divide this number by 20. As such, we arrive at an 80% first-time yield.

Why It Matters

While there are many metrics and measurements we can gather data from in Six Sigma, delivering a defect-free product should be the top of your concerns. First-time yield more than accounts for that, letting you see where issues might be arising in the production. As such, this becomes a powerful tool at your disposal.

3 Benefits of Attending to First-time Yield

Having the data regarding first-pass yield will help you understand where your process stands on the issue of quality.  It helps you understand where you are and quickly puts a spotlight on issues that need to be addressed to get to the next level of quality.

Great Measure of Efficiency

First-time yield is a very easy metric for all members of the team to recognize. If a product doesn’t pass, there is an issue tied to why it didn’t pass. This data is easy to communicate and is often used as part of overall efficiency calculations. These can include OEE (overall equipment efficiency).

Identifying Areas of Improvement

Yield information in general is how we hunt down inefficiencies due to quality. First-time yield, along with throughput yield, are key metrics used to determine where the quality issues are occurring. They also help understand the impact on the system. 

Looking at the lowest first-time yields within a larger process will point you in the right direction on where the largest opportunity for improvement can be found. Identify and analyze these steps first. Utilize a Pareto chart to identify the largest contributors to the lower first-pass yield. Finally, you’ll need to work hard on eliminating or minimizing these issues.

Allows for Rapid Identification of Issues

It is typically easier to measure first-time yield than other metrics. Metrics that are easier to measure can also be easier to identify more quickly, allowing for a faster reaction. Automatic data collection systems are common. Some are capable of collecting lower-level data that can point toward key impacts.  

3 Best Practices for First-pass Yield

• Remember that even if a single first-time yield appears high when you take the multiple steps that have yields and calculate the throughput yield, the overall process may have a poor rolled throughput yield. Always strive to get your first-time yield as high as possible.
• Be wary of automated data collection systems. These systems can be a great source of yield information, assuming data fidelity. Many do not collect the level of data that will be useful to help determine the root cause of the yield issues. Even with this data at your fingertips, be sure to visit the area where the work is performed. Watch the process and discuss known issues with the personnel performing the work daily.
• Be sure to frequently revisit first-time yield, as well as your other yield metrics. Great measurements can turn into poor measurements very quickly. The time it takes to identify and address the impact on yield is time that will cost you time, money, and possibly your reputation with your customers.

Other Useful Tools and Concepts

While we’ve spent a fair bit of time covering yields, that isn’t the only thing that matters in Six Sigma. As such, you might want to transform your DOE, something the Taguchi Method excels at. This approach simplifies experimental design, however, it isn’t the only tool at your disposal.

Additionally, learning how to interpret data is one of the cornerstones of Six Sigma. While you might be up to speed with most statistical methods of interpreting data, looking for variation might have you puzzled. With that in mind, you might enjoy our guide covering special cause variation.

First-time Yield Is a Great Metric to Identify the Health of the Steps in a Process

First-time yield is an easy metric to calculate and communicate to your team, allowing for quick response time to quality issues. When used in conjunction with other yield metrics, it is useful in gaining a clearer picture of the overall efficiency of your operation.