ABSTRACT
Multistation assembly machines may be classified into two main groups according to the system used to transfer assemblies from workstation to workstation. The first group includes those assembly machines that transfer all the work carriers simultaneously. These are known as
indexing
or
synchronous machines
, and a stoppage of any individual workhead causes the whole machine to stop. In the other group of machines, which are known as
free-transfer
or
nonsynchronous assembly machines
, the workheads are separated by buffers containing assemblies, and transfer to and from these buffers occurs when the particular workhead has completed its cycle of operations. Thus, with a free-transfer machine, a fault or stoppage of a workhead will not necessarily prevent another workhead from operating, because a limited supply of assemblies will usually be available in the adjacent buffers.
