Quality beyond torque

More than torque

In past blogs, we examined quality inspections that were all torque related. Posts covering this included:

• 3 reasons why Quality Assurance should begin with Residual Torque
• Tool validation vs tool calibration

Surely, these inspections are important for a manufacturing plant to check the quality of their tightenings, but there’s more than tightening in the production process. The quality of the goods being produced depends also on the molding, painting, sewing, welding, gluing processes and so on.

More variables need to be inspected. In this post, we will try to create order with easy classifications. We can split all the non-torque inspections into two main categories:

1. Qualitative inspections
2. Quantitative inspections

Quantity

Quantitative inspections are the ones that have a numeric result. All the torque inspections fall into this category, for example.

Other types of inspection we can think of are length inspections where the dimensions of components or of the product itself are being collected. Or the quantity of a liquid in a container can be measured to have a volume inspection.

In all of these cases, the inspectors collect a series of numeric samples. We already know a statistical tool that helps us evaluate a collection of numeric samples and that’s the Cm/Cmk.

Is this case, we would talk about a Cp/Cpk, as the “P” stands for process instead of the “M” that stands for machine. The formulas are the same but the name changes are we are analyzing the output of a process and not the behavior of a machine.

Quality

Qualitative inspections, on the other hand, do not collect a numeric value. An example of this could be a visual examination of a seat in search of defects like creases or tears.

In this case, there are no numeric values to collect here, but we are collecting data as well. Here, we are collecting strings that represent eventual flaws in a product. The statistical tool that can help in this scenario are Pareto charts.

Pareto charts give us a graphical representation of occurrences. The more occurrences we have of a specific event, the taller the bar representing the event would be. These diagrams help quality teams to address first the cases that create the most occurrences and thus the most quality defects.

To learn more about our products that can be used for both quantitative and qualitative inspections, please visit our STpad and STpalm product pages.

Have a question? Want to schedule a Walk the Line tour of your facility? Contact Atlas Copco today.