Cassette Drop
Automated Testing Fixture for FK Cassette and Dispenser System
The Challenge
To simulate the repeated stress placed on cassettes by pharmacy technicians when rapidly filling cassettes and dispensers with medication.
The Outcome
The enhancement of the syringe retention mechanism, by discovering its unreliability. Subsequent mechanism designs were tested to ensure the change proved to be more reliable and prevent accidental syringe dispensation upon insertion.
Role
Test fixture design, prototyping, CAD
About
This project focused on creating a test fixture to simulate and evaluate the durability of cassette usage in pharmacies, particularly the stress of repetitive insertion and removal. By employing a precise mechanism involving linear actuators, electromagnets, and custom 3D-printed parts, it facilitated the iterative improvement of the syringe retention mechanism. The result was a more reliable cassette system, capable of withstanding the demands of frequent use without compromising syringe security.
I designed a test fixture that emulated the continuous lifting and dropping of cassettes into the dispenser base to replicate the most damaging action of a pharmacy technician on this product. This setup was pivotal in determining the cassette's longevity through numerous removal and insertion cycles. The "lifting" mechanism utilized tubular steel and introduced perforations to achieve the desired weight and functionality. Above each cassette was a linear actuator equipped with an electromagnet. To mount the linear actuators, and attach the electromagnets, I designed several custom parts utilizing the Markforged 3D printer and the durability of Onyx composite-based material. When an actuator failed, it was easily replaceable given the 3D printed parts were made for this specific application.
A photo interrupter was implemented to track the cassette's position. I performed maintenance after 100,000 cycles and implemented preventative measures after testing each set of three cassettes to ensure no faults with the test fixture. In collaboration with an electrical engineering teammate, we employed an Arduino Mega to control the system with motor controllers and relays. It was found that the syringe retention mechanism was not adequate in the case of firm insertions. This mechanism went through multiple design iterations, which were all tested on this fixture for verification, to confirm that no syringes would drop out unintentionally. This fixture proved vital to the iterative design process of the syringe dispenser system.
