RNA were contacted with a request for a fully automatedquality control and inspection system to handle and inspect plastic mouldingcomponents. The request was from a recently built UK based productionrequirement for a global leader in the food and beverage industry.
The system must handle with minimum changeover twocomponents that are physically different in size and shape. A majorconsideration in this application was the complexity and fragility of thecomponent parts. The system must not cause any damage to these parts, whichhave a detailed periphery.
The system must inspect from all three planes: 1. Top fordamage and OCR (optical character recognition); 2. Bottom for diameter and damage; 3. Side fordamage, height and profile. The system must detect and expel 100% of thosereject components, but critically must not damage the components.
Additionally, the customer required a complete system withminimum requirements below:
1. The system must be capable of operating at up to a rate of1200 parts/minute.
2. It must be designed to meet food and GMP standards.
To enable the system to deliver 1200 parts per minute thedesign utilised a twin headed system with duplicate rotary feeders, conveyors,glass disc and reject segregation, with a common good part collection. Thishandling solution involved the innovative idea of a “rotating glass disc”.
The components are fed from a centrifugal feeder, onto aconveyor system and fed individually onto a rotating glass disc. Due to thedesign of the components, they have a unique tendency to “castle or double up”,causing problems in the handling and inspection, resulting in false rejects.These problems are one of RNA strengths and were solved with the expert use ofgating and a non contact accumulation system, while still ensuring that therewas no damage caused to the components.
An encoder and trigger sensor were fitted on the rotatingglass disc. Once a component part had passed through the trigger sensoran encoder count is stored. The PLC then tracks the components around thedisc triggering the appropriate cameras and ejecting reject components. Good components continue around the disk being gently swept off down a chuteinto a collection box.
A PLC monitors a count of all good and reject the componentsfrom both heads which maintain correlation over continuous 24/7 production.
The cameras used in the inspection system utilise the latesttechnology high resolution cameras with Telecentric lens and lighting. This was required to achieve repeatability of measured values, with aone-micron resolution incorporating 20 microns accuracy over 10,000 measured parts.