Forming process using an outer sacrificial layer
One aspect relates to a process for preparing a shaped metal product, wherein a monolithic metal precursor surrounded by a sacrificial outer element is formed to smaller dimensions, and the sacrificial material is subsequently removed. One aspect further provides a composite for preparing a shaped metal product, and a shaped metal product. Such shaped metal products can be used to manufacture an active implantable medical device or sensor.
1. A process for preparing a shaped metal product for a medical device, wherein the process comprises:
1) Providing a sacrificial outer element comprising a cavity A;
2) Providing a monolithic metal precursor comprising a cavity B;
3) Providing a sacrificial core element;
4) Preparing a composite precursor by inserting the monolithic metal precursor into cavity A of the sacrificial outer element, and by inserting the sacrificial core element into cavity B of the monolithic metal precursor;
5) Forming the composite precursor obtained in 4) to obtain a formed composite having a smaller outer diameter than the diameter of the composite precursor obtained in 4);
6) Separating a composite disk from the formed precursor obtained in 5);
7) Removing the sacrificial outer element and the sacrificial core element from the composite disk obtained in 6).
2. The process according to claim 1 , wherein the outer shape of the monolithic metal precursor, as seen in a radial cross section, has an open or a closed outer shape.
3. The process according to claim 2 , wherein said closed outer shape is a shape selected from the list consisting of oval, polygonal, cubic, rectangular, and circular.
4. The process according to claim 2 , wherein said open outer shape is a shape selected from the list consisting of U-shaped, L-shaped, S-shaped or H-shaped.
5. The process according to claim 1 , wherein the inner shape of the monolithic metal precursor, as seen in a radial cross section, is a non-circular shape.
6. The process according to claim 1 , wherein the sacrificial outer element and the sacrificial core element together form a monolithic metal element.
7. The process according to claim 1 , wherein the monolithic metal precursor is prepared by at least one process selected from the group of electrical discharging machining, additive manufacturing, deep-hole drilling and milling.
8. The process according to claim 1 , wherein the monolithic metal precursor comprises a metal selected from the group consisting of platinum, gold, iridium, steel, titanium, hafnium, niobium, tantalum, cobalt, nickel, chromium, zirconium, rhenium, tungsten, molybdenum, and alloys of any one of these metals, selected from the group consisting of nickel cobalt alloy, steel, platinum and platinum iridium alloy.
9. The process according to claim 1 , wherein 5) comprises a drawing process, wherein said drawing process is carried out with a deformation factor of between 5 and 40%, per individual drawing, or with a die cast having a total included angle 2 α in the range of from 5 to 20°.
10. The process according to claim 1 , wherein 5) comprises a drawing process, wherein said drawing process is carried out with a deformation factor of between 15 and 30%, per individual drawing, or with a die cast having a total included angle 2 α in the range of from 5 to 15°.
11. The process according to claim 9 , wherein the composite precursor is annealed between individual drawing steps of said drawing process.
12. The process according to claim 1 , wherein 5) comprises an extrusion process.
13. The process according to claim 1 , wherein the monolithic metal precursor is formed in 5) to adopt a smaller dimension without substantially changing its overall geometry.