The Challenge
A company that supplies scientific instrumentation approached us with the need for a system to automate the hydrophobic coating of cartridges.
The Solution
Using NI CompactRIO hardware, precision motors, and a LabVIEW motor control architecture, we built the customer an industrial six-station assembly fixture to increase their manufacturing throughput and quality assurance.
The Modularity of the System
Stack Dispenser:
The plastic cartridges were loaded in left and right stacks of 250.
Escapement Mechanism:
A mechanism that uses pneumatic actuators to give the controlled release of a left and right half to the plastic cartridge.
Hydrophobic Coater:
The machine used a custom brush attached to a pneumatic slide to evenly apply the plastic with a hydrophobic (water-resistant)resin coating.
Oven & UV Curer:
The left and right halves would travel on a conveyor through an oven and high-strength UV curing light.
Camera Vision Inspection:
The cartridge halves would be positioned via conveyor on a zebra-striped background. A camera conducting a vision inspection using machine vision algorithms to ensure the translucent coating was even and free of bubbles.
Restacker:
The left and right halves were restacked into hoppers.
CompactRIO:
3 x NI-9145 8 Slot Chassis, EtherCAT bus connector, used to control the system I/O.
Left: A variable frequency drive (VFD) sets the programmable speed of the conveyor carrying cartridges. Right: Stack dispensers using Sick proximity sensors to detect stack levels.
System Highlights
Stack Dispenser & Escapement Mechanism:
Four pneumatic actuators that programmatically released cartridges one by one.
Hydrophobic Coater:
A two-part peristaltic pump released a precise amount of hydrophilic coating which was evenly applied using a brush attached to a pneumatic slide.
Oven & UV Curer:
UV Curer set the coating under high heat and the oven (500± ºF) vaporized any residual solvent leftover from the coating.
Camera Vision Inspection:
Used two Basler cameras with Edmund Optics lenses in two different positions.
Spectral position, direct reflected light, which was used to spot potential defects, second camera positioning with zebra lines were used to determine imperfections (bubbles in coating, etc.)
Restacker:
Pneumatic restacker
Left: A pneumatic on the assembly line pushes cartridges to the side that are determined rejects by the camera vision inspection. Right: A Vexta DC brushless motor powers the conveyor belt.
Technical Specifications
Stack Dispenser
4 x Neumatic Actuator Release Cylinder & Valve
4 x Custom Escapement Fitting
Hydrophic Coater
2 x Watson Marlow Peristaltic Pump
2 x Custom Brush
2 x Pneumatic Linear Slide
Oven & UV Curer
Camera Vision Inspection System
2 x Basler Running Line Scan Camera
2 x 75 mm Focusable Double Gauss Lens
Conveyor
4 x SICK Variable Frequency Drive
8 x Sick Proximity Sensor
4 x Solenoid Operated Pinch Valve
1 x Acer Operator Monitor
4 x CompactRIO NI-9145 8 Slot Chassis, EtherCAT bus connector
1 x LabVIEW 2020