Oven with slotted doors for potting distal end of imaging catheters
Intravascular Ultrasound (IVUS) catheters have imaging elements arranged in a circular array mounted on the distal end. They are used for real-time viewing of artery and veins to help diagnose conditions.
Process: Drying and Heating of Imaging Catheters.
The distal tip of imaging catheters is filled with liquid resin to seal and protect the elements. The resin is preheated prior to the potting process to allow the mixture to flow better. Once the catheter tip is filled with resin it is cured in an oven.
Since only the tip of the imaging catheter needs curing the oven must be able to receive just the tip of the catheter to avoid unnecessary heating of the rest of the catheter. Consistent and repeatable temperature is critical for getting reliable potting results.
The customer was having difficulty achieving uniformity with their existing oven solution. The ovens had an open void in the chamber that resulted in heat loss near the opening. And the solid bottom trays they were using to carry the catheters was restricting airflow. Air flow needed to be precisely directed over the top portion of each tray in order to achieve the correct process requirements and horizontal flow. The trays did not extend all the way to the back side of the ovens, so maximum air flow to the work area was not achieved. That led to inconstant performance and a 4% failure during the curing process. An unacceptable amount for such an expensive component, and time and energy consuming process.
The solution Despatch provided was a modified, 18 cubic foot LBB model lab oven with slots added to the doors of the oven to allow the customers trays to be inserted without opening the oven. Silicone flaps cover the slotted openings to prevent heat from escaping. Despatch engineers investigated ways to improve air flow characteristics. The first step was eliminating the open space caused by asymmetrical loading of the oven. This led to the addition of a partition that would meet with the inserted trays, blocking off a portion of the oven chamber. This area still received warm enough air to help maintain uniformity, and it redirected a larger portion of the air movement over the work area. The second step dealt with the problem of the restricted horizontal flow. To address this, adjustable louvres were placed in locations that would direct the air over the top of the customer’s tray design.
The results were an air flow that spread evenly over each work tray and afforded an unobstructed path to the area between the 2 vertical rows of trays on return to the circulation fan. An oven chamber uniformity certification was provided and testing in Despatch’s Innovation Center proved the concept.
Process failure was kept to a minimum, increasing output and profitability from catheter production. Energy use was reduced by being able to fulfil manufacturing quotas with fewer process cycles.