Improving Inventory Accuracy with X-ray Component Counting
BY DON NAUGLER, VJ ELECTRONIX INC.
Having an accurate inventory is critical to any production process. This is especially true in a dynamic SMT line where frequent changes take place. To maintain the highest accuracy, compo-nents must be counted each time they are returned to stock.
Many pick-and-place systems will track and report component usage, including mis-picks. However, error still will exist such as losses when load-ing or unloading feeders and the more than occasional use of short pieces of tape for rework and R&D purposes.
The common method for verifying component count in reels is manual reel-to-reel counters. To use these counters, the operator must load the reel, feed the tape into the counting mechanism and insert the lead end of the tape into a take up reel. The operator must carefully count the number of components between the lead and the count mechanism because these will not be included once the counting process starts. Additionally, the operator must set the tape pocket pitch. These are both opportunities for counting error.
The tape is then fed onto the take up reel to complete the count. At the end of the process, the tape must be fed back onto the original reel. This entire process takes several minutes. The requirement for handling increases risk of more lost components as well as ESD hazards and exposure to moisture.
X-ray based component counters substantially reduce counting time and can improve counting accuracy. The simplified operation also reduces han-dling risks. Many systems allow count to happen inside of moisture and ESD barrier bags.
X-ray counting uses transmission X-ray to present an image where individ-ual components are easy to see, and the tape and the reel are effectively hidden. Computerized algorithms are applied to recognize the components and to deter-mine the number (component count).
In most cases, these algorithms rely on predefined parameters to help them to separate individual components from the background and from adja-cent components. Smaller components can be particularly difficult as the component size approaches the resolu-tion limit of the X-ray system.
X-ray based component counters reduce counting time and can improve counting accuracy. The simplified operation also reduces handling risks.
At the other extreme, wide com-ponents also are difficult due to the parallax effect where X-ray is transmitted at a greater angle towards the outer circumference of larger reels. This parallax causes the image of one tall component to overlap the image of an adjacent component, making separation of the two images hard to accomplish.
The VJ Electronix XQuik II addresses these challenges with novel imaging techniques and advanced counting algorithms. VJE’s unique imaging provides the highest res-olution for counting. The XQuik detector uses a line scan, producing an image with higher signal to noise and reduced parallax. The end result is significantly more accurate counts of 01005 components, down to metric 03015 capacitors.
The proprietary XQuik AccuCount algorithms are completely automatic. Most components count accurately with-out any type of advanced teaching or programming1. The algorithms quickly identify individual components, regard-less of type, size and shape. Operation is no more complex than loading reels and pressing the scan button.
The final step to ensure the greatest accuracy and to remove one more cumbersome manual intervention is to automate the updating of inventory count data. In addition to the option of using a barcode reader and label printer, the XQuik may be integrated with any MES or inventory storage system. VJE provides a standard data input/output software module (DLL). Customers are given source code and instructions to modify the DLL to precisely match their particular needs. The company also can make modifica-tions as a value-added service.
With the average return on investment reported to be well under one year, XQuik will help improve productivity as well as the bottom line.
the Library function to address these components.