Fused Deposition Modeling (FDM) technology is an additive manufacturing process that builds parts layer by layer, using production-grade engineering thermoplastics and data from computer-aided design (CAD) files.
The ability to build plastic components with complex geometries is revolutionizing manufacturing in many industries, including medical technology. It offers cost and lead time savings in addition to improving accuracy and safety. The ability to replace metal components with plastics is incredibly useful in technology such as an MRI machine.
Example of Advanced Applications in Medical Technology
MRI technology helps diagnose a variety of conditions, from torn ligaments to tumors, and brain and spinal cord issues, using powerful magnets and radio frequency signals to take highly detailed cross-sectional images of internal body structures including organs, soft tissues, and bones.
The use of metals in an MRI machine must be minimized to avoid interference, which means complex plastic components are required. One example is a special coil that interfaces with the part of the body to be imaged and is composed of a combination of plastic parts and silicon molding. It must possess low proton signal strength, have a low magnetic field distortion, and a high radio frequency dielectric strength to safely insulate the patient from electrical shock.
Cutting corners isn’t optional when lives depend on technology to work correctly. Previously, a typical coil was produced with a delivery lead-time of 16 weeks for one set of parts, and cost $20,900 with a considerable amount of expensive material waste.
FDM thermoplastic parts can be built to virtually any geometry that engineers can imagine and free of design constraints. This often results in better-performing machines that can be produced at a lower cost, are less expensive to maintain and eliminates material waste.
The bottom line impact for manufacturers who adopt FDM technology has been dramatic.
One exciting example is Virtumed LLC, a company that produces coils for high magnetic field and research MRI machines. Virtumed LLC uses FDM materials and 3D printing to cut their costs by 78% and lead-time by 94% for a typical 24-component coil.
FDM Soluble Cores
In the past, computer numerical control (CNC) was used to produce patterns from polyurethane board to build clamshell molds which produced hollow composite parts.
To eliminate the high cost and long lead-times, many companies have switched to a method that replaces the mold with an FDM soluble core.
The tedious process of laying up the two mold halves, then laying up the part in each half, and then bonding the two halves together, can now be achieved by wrapping the composite cloth around the soluble core. After the part has cured, the core is simply dissolved.
FDM soluble cores are strong enough to withstand the loads of composite manufacturing processes without the risk of damaging the part during core extraction because the core melts away as it soaks in a liquid bath.