D shaped wire can be achieved by grinding a flat end into a round wire. Typically a d shaped wire is not ground on the centerline but at a point "less" than the midpoint. If you are looking at the face of the wire it looks like a capital D hence the name D shaped wire.
Modern Grinding has manufactured D shaped wires, mandrels, needles and pins for multiple medical device applications. We have added PTFE coating and electropolish as a post finish process.
Some of the projects we have done at Modern Grinding include a taper or transition from a flat wire to a round wire. Some are d shaped for the entire length of the wire. We can achieve tight tolerances on these types of transitions and manufacture to your needs.