A new optical pellet screening system employs a combination of LED illumination, cameras, and air blowers to detect and remove pellets with black spots from a stream of resin pellets with a resolution (spot size) of 0.03 mm. The Super Platon KP-10000T from Kubota (Tokyo) was recently installed at an Asian elastomer compounder.
The Super Platon employs eight lighting units, each with 300 LEDs, to shine diffuse light on the pellets, thereby eliminating black shadows. If black pellets are detected by any of four 5000-pixel cameras, appropriately positioned high-speed air blowers from an array of 20 are actuated to blast the offending pellet/s out of the passing stream with minimal ejection of good pellets. Detection rate is said to be 99% and the unit can process one ton per hour.
The system can be operated using either suction or pressure delivery for transfer of pellets to the storage tank. The system supplied to the elastomer compounder was customized to eliminate issues with pellets bouncing within it and accidently getting direct to the rejected pellet box. This involved applying a nickel oxide-filled PTFE resin coating on the offending components. This modification reduced the overall quantity of pellets rejected from 6% to 0.2%.
The unit was on show at the recent Tiprex show in Bangkok together with another new product from Kubota, the NX Feeder. This gravimetric feeder features an agitator oriented at 45 degrees that reduces bridging. It boasts an accuracy of 0.5% and a weighing capacity of 40 kg. The system is equally suited to feeding of resin pellets, resin powders, talc, and glass fiber.