Considerations

The size of a standard batch is determined primarily by the physical constraints of the production facility.  (The Manufacturing Engineering User Manual discusses more fully how batch size affects the way routings are defined and the way production schedules are calculated.)  Similarly, the primary factor in determining the stockkeeping unit of measure for each item is the way you store and track inventory.

When defining batch sizes and units of measure, however, you should keep in mind how they affect the way product structures are defined.  The quantity of component required to produce a parent product is based on the standard batch quantity, parent's stockkeeping unit of measure, and component's stockkeeping unit of measure.  For example:

If:

Then:

5 boxes of the component are required to make 3 dozen of the parent.

When you define stockkeeping units of measure and batch quantities, you should try to choose ones that will make it easy to specify component quantities accurately. 

In many cases, it might be appropriate to use a stockkeeping unit of measure of "each" and a batch quantity of one.  For example, a bicycle manufacturer would have no trouble specifying the number of wheels required to make each bicycle.  It might be simple to track inventory and plan production based on individual bicycles.  This solution applies to all environments that do not use batch sizing.

In other cases, finding the appropriate units of measure and batch sizes might be more complex.  Using the chocolate chip cookie example again, assume that it takes 1 pound of salt to make 100 boxes of cookies (each of which contains 36 cookies).  The table below shows how the quantity per batch for the salt will vary depending on how the stockkeeping unit of measure and batch quantity for the parent item are defined.  In this example, we assume that the stockkeeping unit of measure for salt is pound.

   Relationship between Batch Size and Quantity Per Batch

This example would become more complicated if salt were stored in some unit other than pound.  For example, if salt is stored in 100-pound drums, the quantity of salt per each cookie would be .000002777.

The Quantity Per Batch field on the data base can store seven significant digits.  In other words, the quantities can range between 9999999 and .0000001.  When you define the quantity per batch for each component, you define the decimal precision for the field.

The limit of 7 significant figures will not cause problems as long as some consideration is given to selecting appropriate batch sizes and units of measure when parts are defined.