Is Real Time SPC Worth it?

Years ago I was in a discussion with some engineers at a large automotive manufacturer where I was told the executive vice president of manufacturing made a statement similar to “I am paying 5 million dollars a year to collect data, what is it getting me?” I am told that no one stood up and explained the reasons. If the event really happened or not who is to say, it does lend reverence to the fact that data collection does have a cost and can the benefits of collection data improve the bottom line?

It has been my personal experience that there are two main reasons why manufacturers are collecting data. The first is to conform to an audit in accordance to the organization ISO standards and the second is to improve quality. Far too often I am finding the first reason to be the prevailing factor for collection the statistical data. There are many reasons why an organization can justify this approach, but in truth, they are the wrong reasons.

When organizations implement an initiative to improve quality, they will typically put in place a standard that has been proven throughout the industry, collecting data through means of a software package for statistical process control (SPC). They may also implement other quality practices such as lean manufacturing or a six sigma to improve the quality practices as well. The key though, is to react to the data before a part is produced that in non-conforming. This is what is termed as real-time SPC.

The object of real time SPC is to give the user tools to react to a process change before a part can be produced incorrectly. If the process is maintained or as in SPC terms “in control”, the benefits of real time SPC can be realized with better quality parts, satisfied customers, and reduced quality cost for internal quality and external quality such as warranty claims, liabilities, sorting, and returns. If these tools are used correctly you can also reduce the cost to inspect such parts by understanding the process and the assignable causes related to the manufacturing of such parts and implementing preventative measures to eliminate the occurrences.

Too often we find manufacturers collecting data and are reacting after the fact. In other words they have the data to prove they have a quality plan implemented but they do not react to what the data is telling them.

When the question is asked, “is the cost of collecting SPC worth it?” , may be better put as a question “is the cost of not collecting SPC data worth it?”

1. The question that you should also ask is how many defective parts do I produce before I know they are defective?

2. How much cost is involved in sorting parts produced to see if they conform to our customers’ expectations?

3. What is the cost to the organization for sending bad parts to our customer?

When answering any of these questions consider the loss of a customer. There is no doubt that collecting any type of data is a cost to every organization. Data though is what we are able to react to. Opinions are just that, opinions, and without data become unsupported. Real Time Data is critical to the overall success of any organization. If used to improve the overall quality of parts produced the benefits will yield increase profitability. That of course is a “big IF.” You have to use the data, not just to pass an Audit.

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