Q: What is the use of the Name Plate Capacity (NPC)? When defining OEE, you tell us we have to define the maximum speed per product per machine (the ‘Standard’).
Arno Koch • The NPC (Name Plate Capacity or Design Speed of the machine) is what the manufacturer of the equipment defined to be its maximum speed. Usually it is defined at a specified situation and a specified product.
There is only ONE Name Plate Capacity (NPC). The NPC nevertheless is usually not equal to the theoretical maximum speed of the machine.
Suppliers take safety margin
If the supplier reports the machine can run at maximum 100 strokes, it is not unusual to discover it can run at 110 or more. Obviously suppliers take a certain margin. Liability or covering deviations between machines is probably the reason.
Adjust Name Plate Capacity when needed
Do not be afraid to adjust your NPC to this higher level. Even if you are not going to run the machine at this speed. In this way you prevent the performance rate ever to go over 100%. In this way you make visible there is a hidden potential in this machine which later might be approached as a chronic loss.
The Ideal Situation versus Reality
In the ideal situation, the Maximum Speed for all your products would be the same as the NPC. The product-mix you are running on a machine determines whether this is true. You bought an expensive machine, because it has a NPC of 480 Mtrs/min. But it is running products that can not go over 240 mtr/min. In that case you might as well have bought a cheaper machine with a maximum capacity (NPC) of 240 mtr/min. Or maybe you might decide to run this products on another, lower capacity machine.
In real live, different product are being produced in different situations.
Different products, different speed
Imagine a machine that has a NPC of 60 strokes per minute. Thin product A can be cut in one stroke. The standard (maximum speed) for this product A on this machine would be 60 products per minute.
The standard is the theoretical maximum speed per product(group) on a machine
The thicker product B be can be cut in two strokes. This means the standard for product B on this machine is 30 products per minute.
So running 60 product A per minute means a performance rate of 100% while running 30 products B also results in 100% performance.
The difference between NPC and Maximum Speed
The NPC is the maximum speed of the machine. Not taking into account possible limitations for a product on that machine. I.e. a cutting machine might be able to cut 4 plies of 80 grams paper at a speed of 150 mtr/min, but only 2 plies of 120 grams paper. ‘The standard’ is the maximum speed for a certain product on a certain machine. For printing and laminating equipment, it is not unusual to have different speeds for different foils (i.e. paper, aluminium or PE foil) and even for different thickness of foils. The NPC is then determined by the rotation speed of the engine, and the standard by i.e. the strength of the foil.
To make the difference visible between the effectiveness based upon NPC versus effectiveness based upon the maximum speed per product, the OEE-Top value is being used.
In the OEE, the performance rate is calculated based upon the Standard (maximum speed per product). In the OEE-Top, every product’s performance is calculated against the NPC. If you see large and frequent differences in OEE and OEE Top, this might be an indicator for reviewing the allocation of your product-mix.
Name Plate Capacity should be the highest possible speed
The NPC should be the highest possible speed for this machine (thus standards never can be higher!). Nevertheless one should consider carefully if this is really true. Don’t feel surprised when you sit besides the machine with a stopwatch and it turns out to be faster than NPC…