First Pass Yield - Part 3

This article is the second in a 4-part series: 
Part 1: Continuous Improvement for Cable/Harness assembly
Part 2: Divide and Conquer your BAD Cables/Harnesses
Part 3: Getting Quality Right the First Time
Part 4: Measuring Success: Why Put a Dollar figure on Quality Improvement?


Getting Quality Right the First Time

Step 4: Take Action

Can defects be prevented from happening? Alternatively, can we provide a means of immediate recognition when errors do occur? How inexpensively can we accomplish this?

The cost of delay in detecting errors:

Principle 5 of The Toyota Way urges us to "Build a culture of stopping to fix problems, to get quality right the first time." 

When we use downstream testing to separate GOOD from BAD and regularly experience "BADs" we get caught up in "testing IN quality." Shrinking the time delay between making an error and discovering the error improves learning (if you don't know you have a problem, you don't know when to stop and repair, which results in scrap and rework). If you've ever experienced a batch of assemblies that were all defective, you'll find that single piece flow, which integrates assembly and test, will eliminate such wastes. By moving test to the point of assembly, assemblers know when to stop if quality is not right! Usually they find their own defects.

Is Training your "Low hanging fruit"?

Sometimes improvement comes simply with training. If assemblers do not understand opens/shorts and miswires, they may benefit from our table on such defects: As assemblers take responsibility for producing "GOOD" assemblies, they need to treat those mystery "BAD" assemblies, with defects they can't understand, as "gold." If you have collected these "gold" defectives but are unsure of their defect cause, start with our tables from last month that help identify root causes for various test results. See "Causes of Bad Insulation" and "Causes of Bad Connections." If you have identified the defect but are unsure how to prevent it from reoccurring, these same tables have been extended with ideas on corrective actions and countermeasures (we welcome your ideas and contributions on countermeasures and corrective actions to improve these tables).

If I need to buy equipment, will it pay for itself?

If you solved your problem with training, with little or no investment, congratulations! In our First-Pass-Yield problem with transformers, we only needed a Which Ender (~$50) and some training to solve the problem. However, implementing process change with rapid feedback (usually some form of error-proofing) to immediately catch defects, often means we need to buy equipment. The cost might not be justified. Let's consider the information that may help you demonstrate how these kinds of changes can save money.

Three key questions:

  1. How much are these defects costing us now and in the future?
  2. How will the change affect current worker productivity?
  3. How much does the equipment cost?

First Pass Yield (FPY) or other quality metrics can help us put a dollar cost on the problem. In some cases, such as anticipated volume increases, we need to add the opportunity of increased business. In simple terms, let's consider the cost of the defect multiplied by how often it occurs.

Solutions that are more cumbersome than the problems they solve make great Dilbert jokes. "How many quality people does it take to change a light bulb? Eleven: One to hold the bulb and 10 to turn the house." Does testing add "one more thing to do?" Or, can the addition of test equipment reduce the time to complete work, as is often the case with guided assembly? The difference between adding recurring cost of doing more work verses subtracting the recurring cost of less work can turn a money losing quality improvement effort into a money saving solution. In simple terms again, how much will the solution add or subtract from current labor costs even when nothing goes wrong? Lastly, how much does the solution cost? Keep in mind, the more complex the solution, the more likely its cost to implement and support will represent a significant part of its price tag.

Let's get real with our dollars

In the following examples, we considered the value of upstream testing using Cirris easy-wire CR and Pin-Sight equipment by entering these costs into a worksheet. Your specific costs can be very different due to the complexity of what you build and the training and skill of your people. Here is one way we might put a dollar impact on our planned improvement: