Here is a prototype implant component made from titanium alloy. It is a laser welded assembly with turning, wire EDM, sinker EDM and laser welding all on a unit less than 5mm tall and about 5mm diameter.
The center screw can rotate inside the mating part but is captive. A laser welded collar holds it in place
This is an end-on view of one of the screwdrivers that forms part of the assembly. It is wire EDM cut from hardened 420M stainless steel, and has a taper to allow it to jam into the screw socket. It also has a center hole to permit another screwdriver to go through it. It is about 0.080″ diameter at the tip. The knurled screwdriver head is 304 stainless steel and was laser welded onto the tip
This is a stainless steel tube that forms part of a needle biopsy instrument. The tubing is very thin…the wall is 0.004″ thick. The slots need square ends and must be precisely oriented around the tube. The slots must be bur-free since other parts slide in the tube. Despite its expense, EDM is the obvious processing choice for a part like this.
The slots are 0.015″ wide. There are six of them around the periphery of the tube which is just over 1.0 mm in diameter. The slots were cut using the sinker EDM by vectoring a six pronged electrode around the tube which was oriented standing up in the worktank. The tube is so flimsy that the first attempts resulted in deformation of the tube when it was clamped into the vee block even though the clamping was performed very gingerly.
Here is the electrode. It is made from copper tungsten which is the material of choice for electrodes that are fragile and must stand up to repeated use. This electrode material is quite difficult to machine on conventional equipment, but wire EDM cuts it very well. The two big flats cut into the body are reference surfaces for aligning the electrode when it’s used. This electrode has burned 6 tubes and still has a good bit of life in it.
Shown is a titanium tee that cannot have any crevices in which bacteria can grow. This requires both an external and an internal weld. The external weld is completely straightforward but the internal weld is a challenge, not only to weld, but also to photograph.
A simple freehand laser weld. The material is Ti6Al4V and the weld is perfomed under argon coverage. This is a fusion weld (no filler wire added) and the customer supplied the individual parts. Fusion welding like this requires excellent fit of the joint, typically with a gap no bigger than 0.002″
Here is the internal weld, about a half inch down a 0.250″ diameter hole. You can see from the photo that it’s at an awkward angle, so the hole in the upright leg of the tee was made a bit larger in diameter to provide a ledge for the beam to hit. This weld requires no strength; its only function is to seal the crevice to prevent bacterial ingress.