A product and its variants that go through similar processing steps and for which common machinery is used just before delivery to the customer.
Product families are important to Lean thinkers because they provide the unit of analysis for value stream maps, which are defined from the last downstream step.
Product families can be defined from the perspective of each customer within an entire value stream, ranging from the ultimate customer (the end consumer) to intermediate customers within the production process.
An example: in a company that produces power tools, a product family could be defined as mid-size power drills that use the same frame and go through the same assembly cell as the final production step before being delivered directly to the end consumer.
A product family can also be defined as the drive motor and its variants assembled in the same cell just before delivery to the customer, in this case a manufacturer of drills.
In addition, a product family can be defined as the drive motor stator and its variants that go through the same manufacturing process just before delivery to
the customer, in this case a drive motor manufacturer.