Power and Free assembly machines (also known as Pallet Conveyor Systems) incorporate component part tooling nests mounted on Pallets which ride on continuous belt conveyors stopping at module work stations to perform sequential or concurrent assembly and test operations. A pallet transfer system can be balanced for simple and complex operations by buffering pallets at station in-feeds and by duplicating stations if a function takes longer than the overall system cycle time.
Power and Free Assembly Systems are typically more ideal for larger or more complex assemblies requiring a higher number of assembly and testing operations. Advantages of Power and Free platforms include high productivity with use of multi-up pallets, high accuracy providing consistent assembly positioning, ability to integrate many modules and provide adequate spacing for operations and maintenance, ability loop pallets off line for rework or alternate operations, and modular construction allowing for easy insertion of additional tracks and modules. When higher outputs are required, Power and Free pallets can be tooled with 2 to 8-up or more station nests for production rates of up to 120 or more parts per minute. Another advantage of the Power and Free system is that system cycle times are not limited by the slowest required operation. In this case, an additional module of the slowest operation can be added to reduced this component of the system cycle time in half.
There are many set-up variations that can be employed when using Power and Free Assembly Systems; Pallets can travel around a single loop or include multi-track off shoots to perform various operations depending on results of upstream operations. Multiple Pallet Systems can also be integrated together in order to satisfy certain assembly and testing requirements or again to balance production cycle times.
As with most other machine platforms, Power and Free machines can be designed to be either fully automatic or semi-automatic. Semi-Automatic Power and Free Assembly Systems are best suited for oddly shaped assemblies where automatic parts feeders would not be cost effective. Semi-automatic versions can also be designed to be upgraded to fully automatic versions once production volumes have sufficiently increased. Fully automatic machines are best suited for higher volume products that would benefit from reduced labor costs and whose components can be fed efficiently automatic feeding systems. These types of machines are also good candidates for being integrated together with injection molding or stamping operations.