Measure Your Workholding
More than likely, you use a number of performance metrics throughout your facility. These metrics may measure sales, inventory, gross margin, spindle uptime, quality, etc. etc. etc. Are you measuring the performance of your fixtures and workholding?
As mentioned in previous blogs, there are a number of methods that may suffice. Simple time studies that measure old set up time vs. new set up time. Rolled throughput yield will show you how many workpieces go into a process vs. how many good finished parts come out. I believe you should be using Overall Equipment Effectiveness (OEE) to measure your workholding.
Just looking at the loss factors involved with OEE should convince you. When taken in context, I believe they speak to the fundamental purposes as to why you would look to improve your workholding. The three-loss factors used to calculate OEE are:
Availability: Availability deals with all events that have interrupted or stopped planned production. Examples could include but certainly are not limited to missing components or incomplete systems to catastrophic fixture failure or “throwing parts”. In addition, workholding that doesn’t repeat well will always cause a stoppage.
Performance: Performance takes into consideration anything that causes production to slow down or not run at full speed. A great example is adjusting manufacturing speeds and feeds or depth of cut because you lack confidence in your workholding.
Quality: Quality looks at any manufactured parts that don’t meet yours or your customers’ quality standards. Poor surface finish, out of tolerance, too much vibration, the list of quality-related workholding failure is a long one.
Once you have identified your loss of productivity, you will simply need to formulate them;
Availability = Actual Run Time/Planned Production Time
Performance = (Ideal Production Time X Total Pieces)/Actual Run Time
Quality = Good Parts/Total Workpiece
Once you have these metrics, simply multiply them together;
Availability X Performance X Quality = OEE
Now that you know your OEE, you will not only be able to measure the performance of your fixtures and workholding, but also be able to determine where you are losing the most productivity or which area of concern you should look at first when improving your workholding.
Measuring the performance of your fixtures and workholding will ensure that these systems contribute to your overall efficiency and profitability. Remember the old saying, “if you can’t measure it, you can’t manage it.”