Inspection system qualification
The quality aspect of visual inspection systems is a topic that deserves attention. Inspection system are used to make a discrimination between good and bad products and these results must be reliable. Especially when the gathered data is used in a six-sigma project for quality improvement.
The design, manufacturing, installation and operation should be in accordance with the original specifications ensuring the inspection system provides the service and measurement accuracy required.
To ensure a good enresult, our projects are lead by a standardized process
User Specification and Requirements
The requirements stated, should be documented and agreed upon, ensuring these are realistic and feasible. At VIMEC we create a USR (User Specification & Requirements) document that is communicated to all parties involved. This contains the original customer-requirements but may also include engineering-input of VIMEC. An approved USR-document forms the basis to take the next step.
This basic document may be complemented by functional & design specifications. These specifications are derived from sample evaluation, mechanical proof of concept, optical verifications, etc.
Standard operating procedures
The construction of the visual inspection application is controlled through ‘Standard Operating Procedures” and checklists (where possible). This is to ensure the same procedure and method is used for each system and results in a specified and controlled outcome. Component and process testing phases are in place to ensure all components are proven to operate according to specification.
Critical components are tagged by a VST (VIMEC Service Tag) and listed in our component registry database. This creates a history of each component and its operation. After the completion of the inspection application the system is transferred to a tester that will subject the system to a variety of test procedure (and will also check the components and the operation). This is documented in the “Qualification document”. Both the engineering responsible and the validation engineer will make an entry in this document before releasing the system.
The qualification document consists of the IQ|OQ|PQ protocols. Based on history and customer requirements we list the Factory Acceptance Test (FAT) and Site Acceptance Test (SAT).
One test method used is the Gauge R&R procedure. A carefully selected sample-set is presented to the inspection system by multiple ‘appraisers’ (operators). The measurement results are processed and the outcome is compared to the specifications. The results are checked for R&R values & Bias. The R&R values provide information about repeatability of the inspection system (is the same results found during each measurement cycle) while the Bias provides information about the accuracy (is the value found the same as the ‘real’ value)
Additional PQ tests
For cosmetic and printing aspects the procedure followed is similar to the Gauge R&R study. A carefully selected sample set is presented to the system. This normally exists of good products that should be accepted & bad products (which can be divided into several classes). A full set of good products is measured and the results are processed. The bad products are then measured and the results are compared to ensure there is a clear discrimination between the good and bad products. VIMEC has dedicated templates in place for information processing.