You are ight about the costs, hillbepa. The vision system becomes simply a fixed cost that can be amortized over multiple parts and sold systems - the same as the RFID reader. However, the tags are a cost that keeps on giving. As Ann pointed out, unless the application is such that individual tracking (or post-sale tracking) is vital, this system would be much more cost effective in the long run.
hillbepa, I agree. The imager cost--which can be well under $10K these days depending on all the variables--is usually less than the cost of an RFID system, and it can do a whole lot more. In smaller plants with simpler parts inventories, this seems to be an overriding factor. But in larger factories, or even in businesses with unusual track and trace needs, such as the Blue C Sushi kaiten sushi restaurant--no kidding, see link below--RFID can deliver what a particular company needs.
It's been a few years since I was in this industry, but I would have to think that the cost of the imager (<$10K ?) is less than the cost of individually tagging each item. E.g., we used vision to verify proper auto assembly ("the BOM for this VIN indicates cruise control should be included; cruise control requires a number of parts, can cameras 'see' those parts?") An aircraft BOM has about 1M parts; it would be problematic to RFID each one, and are the parts still functional after the RFID has been applied?
Also, as you imply, the vision system can check for positional and quality concerns.
RFID is quite complex and not inexpensive to implement. It also doesn't provide much except location information, and certainly not the inspection type data that vision provides. If you also needed inspection data, that would mean implementing two systems, one with RFID and one with vision, and then trying to integrate the incompatible data between the two. That would be a lot more expensive.
Moreover, with vision you can capture a huge amount of data about products and components almost instantly. In this aerospace example, the data codes used are not unlike the standard data matrix codes used in electronics. These are essentially barcodes on steroids, and the infrastructure is well in place for attaching, reading and tracking them, in electronics, and in aerospace.
As usual, much depends on the particular application.
Given the need to track and trace assemblies during aerospace manufacturing, wouldn't RFID or some sort of sensor system be a better fit for this kind of application rather than what I imagine are costly machine vision cameras? Or is the camera necessarily for easily and quickly identifying problems or quality issues?
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