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Using CompactRIO to Automate the Hydrophobic Coating of Cartridges


Hydrophobic Coating of Cartridges
Hydrophobic Coating of Cartridges

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






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