US 11,864,943 B2
Metal injection molding for stethoscope chestpiece
Martin B. Kays, Columbia, MO (US); Paul R. Cassimus, Columbia, MO (US); and Brandon J. Storhaug, Hugo, MN (US)
Assigned to 3M Innovative Properties Company, St. Paul, MN (US)
Appl. No. 17/250,943
Filed by 3M INNOVATIVE PROPERTIES COMPANY, St. Paul, MN (US)
PCT Filed Oct. 2, 2019, PCT No. PCT/US2019/054167
§ 371(c)(1), (2) Date Mar. 31, 2021,
PCT Pub. No. WO2020/072561, PCT Pub. Date Apr. 9, 2020.
Claims priority of provisional application 62/741,897, filed on Oct. 5, 2018.
Prior Publication US 2021/0369233 A1, Dec. 2, 2021
Int. Cl. A61B 7/02 (2006.01); B22F 3/10 (2006.01); B22F 3/22 (2006.01); B22F 3/24 (2006.01); B22F 5/10 (2006.01); G10K 13/00 (2006.01)
CPC A61B 7/02 (2013.01) [B22F 3/1021 (2013.01); B22F 3/225 (2013.01); B22F 3/227 (2013.01); B22F 3/24 (2013.01); B22F 5/10 (2013.01); G10K 13/00 (2013.01); B22F 2003/242 (2013.01); B22F 2003/247 (2013.01); B22F 2998/10 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A stethoscope chestpiece comprising:
a body member having a bottom surface;
an ejector mark disposed on the bottom surface;
wherein the stethoscope chestpiece has a weight of at least 50 g, and a surface roughness (Ra) no greater than 1.6 microns in an unpolished state and reflectivity (% R) of at least 60% in an unpolished state,
wherein the stethoscope chestpiece has been produced by
injection molding, extruding, or pressing a metallic thermoplastic composition into a mould forming a green molded body,
debinding a portion of binder material from green molded body to form a brown molded body without reducing the temperature by more than 80° C.;
sintering the brown molded body to form the stethoscope chestpiece.