In many applications, “good enough” often is not. Sony produces MP3 players, which are destined for a demanding consumer market, so quality is paramount. To ensure quality, managers at the company’s Malaysia facility sought a device that could read the codes and traces on the printed circuit boards that go into these devices. Product tracking is essential to prevent costly recalls and product mix-ups as well as help with “damage control” in the event of a problem.
The old code reading system was inaccurate, which led to high rejection rates that cost the company a lot of money in terms of re-work and rejected units. Thus, management installed the In-Sight® 5110 for code reading from Cognex Corp., Natick, Mass.
Each printed circuit board (PCB) rides on a conveyer through nine production lines and is marked with a Datamatrix code containing product information in ten characters that measure 1 mm x 1 mm in size. The plant produces 40,000 units a day. The ideal reading system must guarantee a read rate of 100%, which would allow the production line to work nonstop and eliminate down time. The previous code reading system was clearly not up to the challenge as it had an average rejection rate of 10,000 units per week.
Four In-Sight 5110 ID readers are mounted in fixed positions. In this application, a conveyor automatically moves PCBs, which are repeatedly placed in front of the reader in either continuous or indexed motion. A “trigger” from an external presence sensor or a position encoder signals the reader that the part is ready for reading.
It is vital that the serial number marked on each PCB heading for the assembly lines be identified and tracked. If the code reader cannot adjust to the product changeovers on lines, it can miss a serial number and lose data. Complicating matters, no two read points are the same. Lighting, environment, or the way the piece is presented can differ greatly, so code-reading equipment must be robust, flexible, and perform reliably under various conditions.
Sony tested different readers available on the market. In the end, the only reader capable of meeting expectations was the In-Sight 5110 ID reader. The 5110 out-performed other systems in the following areas:
–its read rate was superior in terms of decoding speed and sturdiness
–its perspective distortion support ensured reliable reading even when at an angle to the PCBs
–the reader attempts to read code several times using different exposure values, adapting itself to the surface of the PCB and increasing the chances of successful reading
–there is no reader retraining required for a product change
–it offers flexible multiple communication channels
–it offers versatile data gathering, which can be essential for a factory database
–it also ensures reliable original character recognition (OCR)
The new readers are now installed on the production lines. Code reading time is now two seconds per read whereas competitors took more than 10 seconds. The reading success rate has increased from 95% to 100%. With a 100% successful rate, the production line no longer stops as a result of a badly read code. There is no longer the need to stop the line for product repositioning or focus adjustment. These factors are saving Sony about $5,000 a week. The company expects a return on their investment within ten months.
:: Design World ::
Filed Under: Electronics • electrical, Vision • machine vision • cameras + lenses • frame grabbers • optical filters