Method of producing needle cannula with reduced end portion by electrochemical etching

Patent metadata

Field	Value
Publication number	US-11065396-B2
Application number	US-201716093940-A
Country	US
Kind code	B2
Filing date	Apr 6, 2017
Priority date	Apr 21, 2016
Publication date	Jul 20, 2021
Grant date	Jul 20, 2021

Abstract

A needle cannula ( 100 ) and a method for producing a needle cannula comprising providing a needle cannula tube ( 10 ) with an end portion ( 30 ). The end portion ( 30 ) comprises an outer surface, and a given type of steel comprising carbon (C) in 0.07 to 0.15% by mass, silicon (Si) in 0.50 to 1.00% by mass, manganese (Mn) in 5.0 to 7.5% by mass, phosphorus (P) in 0 to 0.030% by mass, sulfur (S) in less than or equal to 0.015% by mass, chromium (Cr) in 17.5 to 19.5% by mass, nickel (Ni) in 6.5 to 8.5% by mass, and nitrogen (N) in 0.20 to 0.30% by mass. The method further comprises establishing an electrochemical reaction to remove material from the outer surface of the end portion ( 30 ), and thereby providing a needle cannula ( 100 ) with a tapered end portion.

First claim

The invention claimed is:

1. A method for producing a needle cannula comprising:
(i.) providing a needle cannula tube, wherein the needle cannula tube comprises an end portion comprising:
an outer surface, and
a steel alloy comprising:
carbon (C) in 0.07 to 0.15% by mass,
silicon (Si) in 0.50 to 1.00% by mass,
manganese (Mn) in 5.0 to 7.5% by mass,
phosphorus (P) in 0 to 0.030% by mass,
sulfur (S) in less than or equal to 0.015% by mass,
chromium (Cr) in 17.5 to 19.5% by mass,
nickel (Ni) in 6.5 to 8.5% by mass, and
nitrogen (N) in 0.20 to 0.30% by mass,

(ii.) providing an electrolyte, and
(iii.) bringing the end portion into contact with the electrolyte,
(iv.) applying a potential between the needle cannula tube and a cathode, and thereby establishing an electrochemical reaction to remove material from the outer surface of the end portion, thereby providing a needle cannula with a tapered end portion.

2. A method according to claim 1 , wherein the needle cannula is more robust than a reference needle cannula tube,
wherein the reference needle cannula is obtainable for comparison by applying steps (ii.) to (iv.) to an end portion of a reference needle cannula tube, and thereby providing the needle cannula,
wherein dimensions of the reference needle cannula tube is corresponding to the needle cannula tube, in such a way that the needle cannula tube and the reference needle cannula tube comprises the same outer diameter, and the same inner diameter, and
wherein process parameters used in steps (ii.) to (iv.) are the same for the needle cannula tube and the reference needle cannula tube,
wherein the reference needle cannula tube comprises a steel alloy comprising:
carbon (C) in less than or equal to 0.07% by mass,
silicon (Si) in less than or equal to 1.00% by mass,
manganese (Mn) in less than or equal to 2.00% by mass,
phosphorus (P) in less than or equal to 0.045% by mass,
sulfur (S) in less than or equal to 0.030% by mass,
chromium (Cr) in 17.5-19.5% by mass,
nickel (Ni) in 8.0-10.5% by mass, and
nitrogen (N) in less than or equal to 0.10% by mass, and

wherein the end portion of the needle cannula comprises a distal end, and wherein the end portion of the reference needle cannula comprises a distal end,
wherein a relative robustness between the needle cannula and the reference needle cannula can be determined by a profile of a diameter of the tapered end portion of the needle cannula, and wherein the diameter at the tip end of the needle cannula is larger than the diameter at the distal end of the reference needle cannula.

3. A method according to claim 2 , wherein the end portion of the needle cannula tube further comprises:
an edge with an outer surface,
a first outer surface portion positioned with a longitudinal distance to the outer surface of the edge,
wherein, when the electrochemical reaction is established, material is removed from the outer surface of the edge with a first material removal rate, wherein material is removed from the first outer surface portion with a second material removal rate, and
wherein the first material removal rate is larger than the second material removal rate,
wherein the end portion of the reference needle cannula tube further comprises:
a reference edge with an outer reference surface,
a first outer reference surface portion positioned with a longitudinal distance to the outer reference surface of the reference edge,

wherein, when the electrochemical reaction is established, material is removed from the outer reference surface of the reference edge with a first reference material removal rate, wherein material is removed from the first outer reference surface portion with a second reference material removal rate, and wherein the first reference material removal rate is larger than the second reference material removal rate, and
wherein the first material removal rate is smaller than the first reference material removal rate.

4. A method according to claim 3 , wherein the second material removal rate is same as the second reference material removal rate.

5. A method according to claim 2 , wherein the needle cannula tube comprises:
an initial end position (XA), defined as a longitudinal position of the end point of the needle cannula tube, before the electrochemical reaction has started,
a final end position (X0), defined as the longitudinal position of the end point of the needle cannula tube, when the electrochemical reaction has finished,
wherein the distance between the initial end position (XA) and the final end position (X0) defines an extension (E), which is removed due to the electrochemical reaction,
wherein the reference needle cannula tube comprises:
an initial reference end position, defined as the longitudinal position of the end point of the reference needle cannula tube, before the electrochemical reaction has started,
a final reference end position, defined as the longitudinal position of the end point of the reference cannula tube, when the electrochemical reaction has finished,

wherein the distance between the initial reference end position and the final reference end position (X0) defines a reference extension, which is removed due to the electrochemical reaction,
wherein the reference extension is larger than the extension (E).

6. A method according to claim 5 , wherein the end portion of the needle cannula tube further comprises:
a second outer surface portion defining a perimeter with a diameter, wherein the second outer surface portion is defined at the final end position (X0),
wherein, the method further comprises:
providing a second outer surface portion with an initial diameter,
removing material from the second outer surface portion thereby forming a second outer surface portion, with a smaller final diameter,

wherein the end portion of the reference needle cannula tube further comprises
a second outer reference surface portion defining a perimeter with a diameter, wherein the second outer reference surface portion is defined at the final end position,

wherein an initial reference diameter is defined as an initial diameter of the second outer reference surface portion,
wherein a final reference diameter is defined as a final diameter of the second outer reference diameter, after the electrochemical reaction has been stopped,
wherein the final reference diameter is smaller than the initial reference diameter, and
wherein the final diameter is larger than the final reference diameter.

7. A method according to claim 6 , wherein the initial diameter of the second outer surface portion is same as the initial reference diameter of the second outer reference surface portion.

8. A method according to claim 2 , wherein the reference needle cannula tube comprises a magnitude of dimensions being same as a magnitude of dimensions of the needle cannula tube within 0.2%,
wherein the reference needle cannula tube and the needle cannula tube is processed under the same conditions and by using process parameter values within 0.2%.

9. A method according to claim 2 , wherein the needle cannula comprises:
a final end position (X0), defined as a longitudinal position of an etched end point of the needle cannula tube, when the electrochemical reaction has finished,
a first position (XB) position with a longitudinal distance to the final end position (X0),
an outer surface defining a profile function (F), where the outer surface intersects with a plane containing a central longitudinal axis (x) and a radial axis (r),
wherein the profile function (F) is defined in an interval between the final end position (X0) and the first position (XB),
a second derivative of the profile function (F) with respect

Assignees

• Novo Nordisk As

Inventors

• Trosborg Jacqueline
• Uggerhoej Jens Christian

Classifications

• C22C38/40

  with nickel · CPC title

• C22C38/04

  containing manganese · CPC title

• A61M2207/00

  Methods of manufacture, assembly or production · CPC title

• C22C38/02

  containing silicon · CPC title

• C25F3/06

  of iron or steel · CPC title