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3 Definition of Speed

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3.1 Base
To calculate the performance rate, the THEORETICAL maximum speed is related to the ACTUAL speed.
The THEORETICAL maximum speed is currently most probably not achievable, just like the theoretical maximum running time will not be achieved.
The goal of the performance rate is to visualize ALL potential, regardless whether it is considered to be ‘realistic’ or achievable.
What IS achievable is not yet discovered; to find out is a task of kaizen teams.
The Theoretical Maximum is based on physical limitations (that cannot be stretched without changing the physics and thus the process), rather than on ‘practical’ or ‘technical’ limits (that can be stretched by kaizen teams).
3.2 Time versus Quantity
The maximum speed can be calculated in time or in number of product; i.e.
  • maximum speed is 10 seconds per product
  • maximum speed is 6 products per minute

Nevertheless since OEE is primarily a shopfloor tool, and people on the shopfloor usually rather talk about ‘units being produced’ than ‘seconds it has taken to produce a unit’, it is preferred to register speed in units, not in time.

The parameters for Performance can be expressed in either TIME or QUANTITY, but QUANTITY is preferred
3.3 Maximum speed of what?
The maximum speed can be determined from the NPC, the Name Plate Capacity (Design speed).
However, mostly there are several product(groups) on a machine with their own derived maximum speed. In such cases, special care has to be taken not to include hidden losses in the maximum speed due to ‘difficult products’ which might refer to ‘products which we don’t control the process for’.
3.4 Name Plate Capacity (NPC)
The NPC should not be taken granted for. More than once it was discovered to include all kind of hidden losses. The manufacturer might have chosen a low NPC for reasons of liability or to ‘fit’ the equipment with other equipment in a line.
3.5 The Standard
The standard is the theoretical maximum speed for a product(group) on the machine; thus the performance rate never exceeds 100%
The derivation of different maximum speeds for different products should be done in a mathematical manner.
Example:
An extruder is designed (and checked for!) extruding max. 500 kg plastic per hour.

 

Product A consists of 250 grams plastic, product B consists of 500 grams. Thus:
  • the theoretical maximum speed for A is 500kg/250gram= 2000 pcs per hour.
  • The theoretical maximum speed for B is 500kg/500gram= 1000 pcs per hour.

 

The theoretical maximum speed for a product-machine combination is called ‘The Standard’.
It is specifically not called ‘Norm’, since this word has negative associations related to piece work for many people in different countries.
3.6 How maximum is maximum speed?
100% OEE = The theoretical maximum capacity of the equipment
This statement should be taken serious. If not done so, situations may (and do) occur where the shopfloor is filled with scrap, the machine is suffering one breakdown after the other and still accounts for 80% or more OEE. How?
70% Availability, 80 % Quality, 143% Performance = 80% OEE !
As soon as the performance rate goes over 100% (indicating the standard is chosen too low!) the beautiful balance of the OEE parameters is broken, and the focus may be taken away from what it is all about: identifying and reducing losses.
In cases where the maximum speed has to be determined based upon a Best Of Best analysis, it should be considered that this BOB is achieved under the former and current circumstances, including current losses.
Since in the end even standards are broken by product- and equipment improvement, the BOB should not be considered too easily as maximum value. As a rule of thumb the BOB value should be raised with at least 10 to 25% to serve as Standard.
At well-chosen Standards, the performance rate will NEVER exceed 100%, unless the product or the machine fundamentally changes
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