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Design
The final design requires the same functionality as the high cost Acland model clamps, while also being easier and lower cost to manufacture and assemble. The following designs work to fulfill these requirements for functionality and accessibility.
Components:
Components:
Slide: Maintains the position of the clamps when stationary. Must allow for clamps to be easily adjusted either closer or farther apart
Mount: Folds onto the slide so clamps can be attached
Handles: Allow for Rizzuti forceps to easily grab and adjust the position or open the jaws of the clamps.
Spring: Experiences the maximum stress when in use, determines the reliability and clamping force of the clamps.
Jaws: Acts as points of contact to blood vessels. Must be aligned to properly apply clamping force from spring.
Iteration Process:
We started working on a new sliding mechanism design using a scaled up model of the clamps with 3D printing. We then moved on to making more designs using a folding template of the clamp from sheet metal. The major change from the previous versions to the current version was incorporating the mounting component into the clamp template, allowing for fewer separate components during assembly. The materials used are tough PLA for the 3D printed model, and 18-8 stainless steel for the metal cutouts. The clamps are 0.007" thick and the slide piece is 0.025" thick.
Manufacturing Process:
Manufacturing Process:
To fulfill the requirements of our components, a high level of precision is required when manufacturing. To achieve this, a laser cutter is used to cut templates from sheet metal which can be produced at a higher scale. This achieves the low cost manufacturing requirement that is needed. Other forms of manufacturing were considered, including 3D printing and metal stamping. But none were able to produce the consistent precision and cost effectiveness as the laser cutting and precision folding method. For the die sets, precision machining or 3D metal printing was used to produce metal die sets that are precise.
Standard Operating Procedure (SOP): Folding Process
Standard Operating Procedure (SOP): Folding Process
These clamps face a lot of hand folding and handling during the assembly process. This reveals a need for a standard operating procedure or SOP to be established in order to properly lay out the assembly process and performance checks to have a successful product. This would act as a guide for any training surgeons to follow in order for anyone to produce these double clamps as long as they have all the required materials and tools. It also provides a baseline for manufacturers that can produce more clamps at a higher scale. This ensures that manufacturing and scalability is possible for these clamps.
Below is a video of the folding process for the double opposing micro clamps:
Folding Tools
Folding Tools
When folding the clamps, any variability in the folding process can lead to variability in the outputs of the clamps. To assist in the folding process, multiple die sets were made in order to ensure the finished clamp sets fulfilled the physical requirements of the clamps.
Spring Die
Spring Die
The first is a spring die set that produces a consistent angle for the spring component of the clamps, ensuring a consistent clamping force.
Clamp Die
Clamp Die
The second set of dies assist in the folding of the mounting tabs, these would ensure the clamps are properly attached to the slide piece as well as produce a consistent sliding force for every clamp set.
Quality Control (QC) for Performance
Quality Control (QC) for Performance
To ensure the performance of the clamps after assembly, two quality control tests were developed in order to check the clamps for proper clamping force and alignment of the jaws. These are the most important qualities to check for as the final output of force to the blood vessels can vary wildly if there are any variations in the folding process. To ensure precision and accuracy of the quality control checks, image processing software is used and analyzed to perfom the checks.
Clamp Force QC
Clamp Force QC
Using two strips of metal fixed parallel to each other, a makeshift spring is made using the two beams as cantilevers. By finding the deflection of the beams, it is possible to determine the clamping force. This is done through image processing of the two beams and analysis done in MATLAB.
Jaw Alignment QC
Jaw Alignment QC
The jaw alignment QC acts to ensure proper force application by the clamps through the alignment of the jaws. If there is any misalignment of the jaws, the resulting clamping force is vastly different than what is expected. This is done through image processing of the clamp jaws from a top down view, with analysis done in MATLAB.
Cost
Cost
Below is the cost analysis of the double opposing micro clamps:
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