100% Vision Inspection Comes to HDPE Bottles
Kerr Plastics, Lancaster, Pa., a producer of injection blow molded HDPE pharmaceutical bottles, never used to inspect every bottle it produced.
Kerr Plastics, Lancaster, Pa., a producer of injection blow molded HDPE pharmaceutical bottles, never used to inspect every bottle it produced. "Like every other company, we would take samples, evaluate them off-line, then go back to make adjustments to the machine," says Fred Bixler, technical manager of quality assurance. However, more stringent quality standards demanded by customers prompted Kerr to become one of the first makers of polyethylene bottles to use on-line vision inspection for 100% quality control. Kerr already had experience with the technology for on-line inspection of bottle caps.
Vision inspection systems are better known in the specialized field of PET bottles for carbonated beverages. They are just starting to make inroads among PE extrusion blow and injection-blow molders, says Ron Puvak, new product marketing director at AGR International Inc., Butler, Pa. Kerr Plastics uses AGR's Conveyor Vision Inspection System (CVIS) to check the base, neck, and sidewall of every bottle it makes, from 30 to 120 cc. "It can identify defects too small for the human eye to see. We simply couldn't employ enough people to get the kind of results we get from CVIS," says Mark Wilson, plant manger at Kerr.
The system has been in place for five months, and scrap rates have gone up slightly, Bixler says, because the unit finds defects that would otherwise have slipped by. He expects production rates to rise as the plant focuses on minimizing those defects.
Helps monitor the process
The CVIS unit employs four cameras placed at 90° for sidewall inspection, plus a single camera each to look at the base and neck of each bottle as it passes by on the 4-ft-long inspection conveyor. The digitized images are sent to the CVIS computer, which compares them with stored images of a good bottle. It records a defect where the images don't match. Kerr looks for thin spots and holes in the base, flash in the neck, and contamination and inclusions in the sidewall. The CVIS system rejects defect bottles automatically, categorizes and stores each incidence of defects, monitors process trends, and sounds an alarm if preset limits are reached.
"Some of the greatest benefits come from its use as a process monitor. The system recognizes process trends and alerts us very quickly to potential production problems," says Wilson. Kerr can trace a problem back to the resin, tool, or machine.
Neither Kerr nor AGR agreed to reveal pricing information.
