New high speed part inspection and sorting system
Original article date: July 1999
Fast efficient component inspection and delivery are vital elements in high speed automated manufacturing machinery. Bob Jackson of Festo describes how the Checkbox system contributes.
The Festo Checkbox family is designed for applications where the limits of conventional handling systems such as mechanical escapement bowl feeders have been exceeded due to speed and part complexity Based on optoelectronics it provides fast non-contact part recognition and orientation quality inspection and sorting of different items on the same conveyer. Contact-free operation reduces wear and tear while improving reliability and consistency. The Checkbox concept was originally developed by Festo engineers to meet quality requirements in their own production facilities.
Checkbox is available in three different formats. Identbox checks parts for conformity and ejects bad and erroneous parts. Incorrectly orientated parts are sent back to the source to be rerun. Countbox adds to this by counting the number of accepted and/or rejected parts and comparing this with a pre-selected target quantity ideal for collating batches of components. Sortbox adds further features again with multiple levels of programmable blow-off eject allowing up to six components to be accurately sorted.
The system suits rotationally symmetric parts as well as pre-orientated parts of any geometry. Part diameters and lengths can range from 0.5 to 80mm and 3 to 80mm respectively.
The Checkbox system comprises a conveyer (80 30 or 9mm wide); a narrow vertically mounted CCD camera array; LED illumination; an industrial PC control unit; and pneumatic ejection/sorting nozzles. Industrial protection is IP54. Standard conveyor speed is 300mm/s. The Checkbox is CE approved and EMC certified. Prices for complete systems start at (UK pounds)8300for Identbox rising to around (UK pounds)10 500 for Sortbox with six nozzles. Stripped down OEM variants are priced at around (UK pounds)5000.
Parts are delivered to the conveyer and pass the scanning head. A profile of the moving part is generated and a precise pixel count is used to determine length and height. Real-time image analysis software sub-divides the profile to establish orientation. These parameters are compared to a good image example stored in memory. Checkbox can memorise up to six different components concurrently.
Additional CheckOpto software zooms to critical areas to measure fine details such as radii chamfers and thread pitches. Off-line software tools provide extra facilities for charting data-logging trend analysis and mathematical/statistical functions.
Dimensional accuracy is 0.1mm for 30 and 80mm conveyors and 0.02mm for the 9mm conveyor. Conveyor speed is programmable and maximum component length is proportional to conveyor speed. Speed achievable for a 10mm long component would be 1800 per minute.
The system recognises new components via a learning process that takes only seconds. The user switches the control system to teach mode selects Orientation-1 and places good components on the conveyor (in the correct orientation) a minimum of four times consecutively. Then the user selects Orientation-2 and feeds the part through a minimum of four times in the wrong orientation. Components chosen for teaching should ideally be at their upper and lower dimension so the box can learn the range. The feed system can be set up for a part changeover by simply pressing a key. Up to 24 different parts can be stored in memory.
Over 100 Checkbox units are already in full time production and a video demonstrating some of these applications is available.
- Festo
- 01252 775000
July 1999