February 29, 2012
Predicting the Future
In the manufacturing world, it is really difficult to predict the future, and many times we make our decisions based on our gut feelings. While InfinityQS can't provide you with a crystal ball, we do have tools that can help you predict the effect of changes in specification limits. How is this possible, you ask? First, let's look at a few situations where this tool might be useful.
Scenario A: Let's say your customer asks you to tighten your specification limits for a specific Part/Test combination. The first thing that might come to your mind is: How will this change affect my business? Or, should I charge more money to the customer? If so, how much more money should I charge?
Scenario B: Every year, upper level management set the KPIs (Key Performance Indicators) goal for the following fiscal year. You would like to use a tool that could help you predict the impact of having a different metric. This could help you determine how capable your processes are or how much effort you will need to put into the next fiscal year to be able to hit your new KPI's targets.
Does this sound familiar? Let's talk about what we can do to help answer some of the questions above. In ProFicient, you can enable override limits in the Capability Analysis Chart. To do so, right click the Capability Analysis Chart, and in the pop-up menu, click Processing. In the Processing Options dialog box, click the Special tab, and under the Special tab, click the Enable Override Limits checkbox.
Using this option, you ensure that the assigned specification limits will be used for analysis purposes, and no new specification limits will be created in the Specification Limit Table. This is great because it will help you analyze "what if" scenarios.
To see this option working, use a Capability Analysis Chart for the OD-Loc B test on the Blue Part. If this chart represents the current specification limits, examine the variables highlighted in red. In this scenario, the Expected Below is 0.012%, the Cp is 1.567, and the Cpk is 1.551.
What will the impact be if you changed your Lower Specification Limit (LSL) from 1.495 to 1.4976?
As you can see in the chart below, by overriding the LSL, the Expected Below has significantly increased to 4.081%, the Cp values has decreased to 1.16 and the Cpk to 0.736.
You can use these values to help you predict the impact of changing the specifications. Not only that, but for Scenario A, you could use the Expected Below and/or the above number(s) and multiply it by your total number of units and the unit cost, and you will obtain the monetary impact of this change. Now you can go back to your Customer with a business plan.
In this example, you only changed the LSL, but you could also do the same for the Upper Specification Limits (USL), or change both limits to analyze both at the same time. This is a great tool that is very simple to use and can definitely help you to save time and money in the decision making process!