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US4859943A
Expired / Lapsed
US
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Inspection method using magnetic particles in a liquid carrier in combination with electrical detection means
Assignee: Babcock and Wilcox Co
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Filing: 1987-12-28
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Granted: 1989-08-22
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Expires: 2007-12-28
Abstract
Abstract A method for inspecting the surface of a workpiece for the presence of flaws using a ferrofluid as a penetrant which is applied to the surface of the workpiece and then scanning the surface of the workpiece with electrical detection means placed adjacent to the surface for providing responses indicative of the presence of flaws in the surface of the workpiece. If desired, a magnetic field can be used to induce the flow of the ferrofluid into any flaws prior to inspection, and for post-inspection cleanup as well. By the use of a ferrofluid, the sensitivity of the electrical detection means, advantageously of the eddy current type, is enhanced in typical applications, and also allows the use of an eddy current probe to inspect workpieces made of nonconductive and/or nonferromagnetic materials.
Inventors
- 👤 Robert S. Evans
- 👤 Wayne M. Latham
- 👤 Thomas Powers
- 👤 Michael O. Robertson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 10:48
CPC Classifications
G; G01; G01N; G01N27/00; G01N27/72; G01N27/82; G01N27/83; G01N27/84
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
85 words
A method for inspecting the surface of a workpiece for the presence of of flaws, comprising: applying a ferrofluid to the surface of the workpiece; scanning the surface of the workpiece with electrical detection means placed adjacent to the surface of the workpiece for producing responses indicative of the pressence of flaws in the surface of the workpiece; and applying a magnetic field to the workpiece to induce the ferrofluid to withdraw from the flaws, after the inspection has been completed, to clean the workpiece.
Claim 2
Independent Claim
85 words
A method for inspecting the surface of a workpiece for the presence of of flaws, comprising: applying a ferrofluid to the surface of the workpiece; scanning the surface of the workpiece with electrical detection means placed adjacent to the surface of the workpiece for producing responses indicative of the pressence of flaws in the surface of the workpiece; and applying a magnetic field to the workpiece to induce the ferrofluid to withdraw from the flaws, after the inspection has been completed, to clean the workpiece.
Claim 3
Dependent Claim
27 words
The method as set forth in claim 1 further including the step of cleaning the surface of the workpiece prior to applying the ferrofluid to the surface.
Claim 4
Dependent Claim
22 words
The method as set forth in claim 2 further including the step of recording the responses indicative of the presence of flaws.
Claim 5
Dependent Claim
28 words
The method as set forth in claim 3 wherein the step of recording the responses indicative of the presence of flaws involves creating a graphical strip chart record.
Claim 6
Dependent Claim
16 words
The method as set forth in claim 1 wherein the workpiece is made of ferromagnetic material.
Claim 7
Dependent Claim
16 words
The method as set forth in claim 1 wherein the workpiece is made of nonferromagnetic material.
Claim 8
Dependent Claim
16 words
The method as set forth in claim 1 wherein the workpiece is made of conductive material.
Claim 9
Dependent Claim
16 words
The method as set forth in claim 1 wherein the workpiece is made of non-conductive material.
Claim 10
Dependent Claim
20 words
The method as set forth in claim 1 wherein the electrical detection means comprises an eddy current source and probe.
Claim 11
Independent Claim
74 words
A method for inspecting the surface of a workpiece for the presence of flaws, comprising: applying a ferrofluid to the surface of the workpiece; applying a magnetic field to the workpiece to induce the ferrofluid to penetrate into any flaws; and scanning the surface of the workpiece with electrical detection means placed adjacent to the surface of the workpiece for producing responses indicative of the presence of flaws in the surface of the workpiece9
Claim 12
Independent Claim
74 words
A method for inspecting the surface of a workpiece for the presence of flaws, comprising: applying a ferrofluid to the surface of the workpiece; applying a magnetic field to the workpiece to induce the ferrofluid to penetrate into any flaws; and scanning the surface of the workpiece with electrical detection means placed adjacent to the surface of the workpiece for producing responses indicative of the presence of flaws in the surface of the workpiece9
Claim 13
Dependent Claim
27 words
The method as set forth in claim 10 further including the step of cleaning the surface of the material prior to applying the ferrofluid to the surface.
Claim 14
Dependent Claim
22 words
The method as set forth in claim 10 wherein the magnetic field applied to the workpiece is created by a permanent magnet.
Claim 15
Dependent Claim
21 words
The method as set forth in claim 10 wherein the magnetic field applied to the workpiece is created by an electromagnet.
Claim 16
Dependent Claim
20 words
The method as set forth in claim 10 wherein the electrical detection means comprises an eddy current source and probe.
Claim 17
Dependent Claim
24 words
The method as set forth in claim 10 wherein the applied ferrofluid has a viscosity of less than 5 centipoise at 80 degrees F.
Claim 18
Independent Claim
72 words
A method for inspecting the surface of a workpiece for the presence of flaws, comprising: applying a ferrofluid to the surface of the workpiece; applying a magnetic field to the workpiece to induce the ferrofluid to penetrate into any flaws; and scanning the surface of the workpiece with an eddy current probe placed adjacent to the workpiece for producing responses indicative of the presence of flaws in the surface of the workpiece.
Claim 19
Independent Claim
72 words
A method for inspecting the surface of a workpiece for the presence of flaws, comprising: applying a ferrofluid to the surface of the workpiece; applying a magnetic field to the workpiece to induce the ferrofluid to penetrate into any flaws; and scanning the surface of the workpiece with an eddy current probe placed adjacent to the workpiece for producing responses indicative of the presence of flaws in the surface of the workpiece.
Claim 20
Dependent Claim
39 words
The method as set forth in claim 16 further including the step of applying a magnetic field to the workpiece to induce the ferrofluid to withdraw from the flaws, after the inspection has been completed, to clean the workpiece.
Claim 21
Dependent Claim
27 words
The method as set forth in claim 17 further including the step of cleaning the surface of the workpiece prior to applying the ferrofluid to the surface.
Claim 22
Dependent Claim
22 words
The method as set forth in claim 18 further including the step of recording the responses indicative of the presence of flaws.
Claim 23
Dependent Claim
22 words
The method as set forth in claim 16 wherein the step of recording the responses involves creating a graphical strip chart record.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-08-21 | 1993-02-20 | 1993-08-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-08-21 | 1997-02-20 | 1997-08-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-08-21 | 2001-02-20 | 2001-08-22 | $7700.00 | Window Closed / Lapsed |