An essential element in pacemaker and defibrillators design is the connection joining the lead to the electronic device. The lead transmits the function dictated by the device to the heart. The junction between the lead and the device is protected from the body and its fluids by a seal plug also known as a "septum".

Septums vary between device manufacturers, but are essentially a molded silicone piece with a "slit" running through it. The slit allows the surgeon to insert a special tool for the tightening of a set screw at the connection. Once the tool is withdrawn through the septum, the slit must close and seal the connection from bodily fluids.

Difficult to make due to their size and need for slitting, an FMI customer took the septum to a new level by integrating a stainless steel flange into their design. The flange (.006" in thickness x .086" in diameter) is molded into the septum, and performs the function of stabilizing the slit to better seal the connection. Not only does positively locating this insert during molding pose a problem, but the insert's configuration would require it to be orientated. An upside down placement of the insert is damaged by the slitting blade, as is the blade itself.

FMI engineers designed the mold required to make this very intricate part manufacturable. They also designed a stand alone device and blade to make the .050" slit. FMI has made the part since 1991, in large quantities to accommodate the rapidly growing pacer/defibrillator marketplace.