1. Field of the Invention
This invention pertains to the field of automated manufacturing equipment, and more particularly relates to automated equipment for verifying that an automated manufacturing machine is correctly configured prior to operating the automated manufacturing machine to produce assemblies at a high rate.
2. Description of the Related Art
In the electronics manufacturing industry, surface mount technology placement machines capable of placing electronic components on printed wiring assemblies during automated assembly line production at rates as high as 14,000 electronic components per hour are common. Such machines typically utilize as many as 140 or more different electronic component feeder magazines arranged in a predetermined order to maintain such a high production rate.
In such a machine it is important that the correct electronic component be loaded in each component feeder magazine and that each component feeder magazine be loaded in the correct sequence on the placement machine. Only in this way will the printed wiring assembly data set, which controls printed wiring assembly manufacture and electronic component placement cause the placement machine to accurately place the correct electronic component in the correct position on each assembly.
In order to perform manufacturing at high production rates, the placement machine feeder magazine configuration must be free of error. Manually checking 140 different component feeder magazines to ascertain that the correct electronic component is loaded in each component feeder magazine and that each component feeder magazine is correctly positioned on the placement machine is time consuming and prone to error. Failure to verify that the setup is correct before beginning production risks producing a large number of defective printed wiring assemblies before the error can be discovered and corrected.
Some manufacturers of surface mount technology placement machines have sought to deal with this problem by including apparatus to test each component before it is placed on the printed wiring assembly to insure the correct component is being placed. Components are typically quite small, and testing equipment must be quite sophisticated and consequently expensive. This approach slows the production rate by a factor of 60 percent or more, and is generally unsatisfactory for this reason.
Other manufacturers have included electronic circuitry, usually a semiconductor chip bearing an identification code or programmable circuitry, within each component feeder magazine. This allows the placement machine to interrogate each component feeder magazine, usually using a gold finger contact connection, and determine that each component feeder magazine is in its correct location. This system requires that each component feeder magazine be dedicated to loading one component part number so that a given component feeder magazine always contains the same component part. This system has no way of checking which part is in which magazine, other than having the operator manually check. Including programmability within component feeder magazines increases the cost and complexity of the component feeder magazine, but does not guarantee the correct component is loaded within that feeder magazine.