[go: up one dir, main page]

GB2164161A - Method of inspecting a surface for flaws - Google Patents

Method of inspecting a surface for flaws Download PDF

Info

Publication number
GB2164161A
GB2164161A GB08521332A GB8521332A GB2164161A GB 2164161 A GB2164161 A GB 2164161A GB 08521332 A GB08521332 A GB 08521332A GB 8521332 A GB8521332 A GB 8521332A GB 2164161 A GB2164161 A GB 2164161A
Authority
GB
United Kingdom
Prior art keywords
coating
film
copolymer
flaws
inspecting
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
GB08521332A
Other versions
GB8521332D0 (en
Inventor
Paul A Matthews
Richard Chapman
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
GRAMOS CHEMICALS INTERNATIONAL
Original Assignee
GRAMOS CHEMICALS INTERNATIONAL
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from GB848422555A external-priority patent/GB8422555D0/en
Application filed by GRAMOS CHEMICALS INTERNATIONAL filed Critical GRAMOS CHEMICALS INTERNATIONAL
Priority to GB08521332A priority Critical patent/GB2164161A/en
Publication of GB8521332D0 publication Critical patent/GB8521332D0/en
Publication of GB2164161A publication Critical patent/GB2164161A/en
Withdrawn legal-status Critical Current

Links

Classifications

    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84Systems specially adapted for particular applications
    • G01N21/88Investigating the presence of flaws or contamination
    • G01N21/91Investigating the presence of flaws or contamination using penetration of dyes, e.g. fluorescent ink
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N19/00Investigating materials by mechanical methods
    • G01N19/08Detecting presence of flaws or irregularities
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84Systems specially adapted for particular applications
    • G01N21/88Investigating the presence of flaws or contamination
    • G01N21/8803Visual inspection

Landscapes

  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Investigating Materials By The Use Of Optical Means Adapted For Particular Applications (AREA)

Abstract

A method of inspecting a surface (11) to ascertain if there are any surface flaws (12) in the surface, comprises the steps of applying a coating (13) in fluid state to the surface (11), permitting the coating to become non-fluid, observing its surface (14) to ascertain the presence of any surface flaws and then removing the coating, preferably by peeling. The coating is a p.v.c./p.v.a. copolymer with an opaque, preferably black, pigment which is applied by spraying to flow over the surface and produce a film with a reflective surface 14. Visible or non-visible radiation which may be stoked may be used to detect flaws. <IMAGE>

Description

SPECIFICATION Method of inspecting a surface This invention relates to a method of inspecting a surface to ascertain if there are any surface flaws.
Hitherto, surface flaws, in for example, metal dies, have been detected either by visual and tactile inspection of the untreated surface by a highly skilled person or by applying a dye, ink or the like to the surface, followed by application of oil to make a reflective layer or by the use of fluorescent oils so that, on visual inspection, surface flaws are emphasised by a different pattern of reflected light in the region of any surface flaw which is present.
Such previous methods rely either on a skilled person performing the inspection or the application of dyes, inks or the like and/or oils to the surface so that the inspection procedure is messy and requires subsequent cleaning of the article inspected.
An object of the invention is to provide a method of inspecting a surface to ascertain if there are any surface flaws in the surface which avoids or reduces these disadvantages.
According to the present invention, we provide a method of inspecting a surface to ascertain if there are any surface flaws in the surface, comprising the steps of applying a coating in fluid state to the surface, permitting the coating to become non-fluid, observing the surface to ascertain the presence of any surface flaws and then removing the coating.
Preferably, the coating is a peelable coating whereby the coating is removable by peeling the coating from the surface (as herein defined).
By "peeling the coating from the surface" we mean that the coating is removed by the application of a tensile force to a free end part of the coating which is transmitted through the coating to a part of the coating still on the surface so that the coating is stripped off by rolling back the coating.
The coating is preferably removable from said surface in at least one piece comprising at least 10% of the area of the surface from which the coating is to be peeled. Preferably, the coating is peelable off in at least one relatively large piece comprising between 50% and 100% of said area and the remainder, if any, being peelable off in a smaller piece or pieces, the or each of which preferably com prises at least 10% of said area, although there may be at least one smaller piece com prising less than 10% of the area to be re moved to completely clear the surface of the coating. Preferably, all, or substantially all, of the pieces comprise at least 10% of said area.
The coating may be applied in liquid state and may be applied by spraying. The liquid may be sprayed by conventional air feed, airless, or by aerosol spraying, the latter permitting a particularly convenient form of packaging for use when relatively small size articles are to be inspected.
The coating may be in the form of a thin film, for example a film having a thickness lying in the range 0.0063-0.051 mm (0.00025-0.002 inches).
The coating may be opaque and of a dark colour such as black and have flow properties so as to provide said film with a smooth reflective surface thereon which conforms to the surface to be inspected, including any flaws therein so that a flaw is detectable by a different pattern of reflection resulting from a deviation in the surface of the film in the region of the flaw.
The coating may be illuminated with white light or with visually detectable light of a specific wavelength or range of wavelengths, or may be illuminated by other radiation outside the visual range in which case suitable sensing means are provided to sense the reflected radiation. In all cases the coating may be continuously illuminated or strobed.
The coating may be a polymer, for example a polyvinyl chloride/polyvinyl acetate copolymer.
The polyvinyl acetate component of the copolymer may comprise between 12% and 16% of the copolymer and have a K value lying in the range 40 to 60 and preferably the polyvinyl acetate component comprises 14% of the copolymer and has a K value of 47.
The coating may be of the following composition: % w/w P.V.C/P.V.A. Copolymer 8-20 Plastisiser 3-8 Silicone Oil 0.01-0.3 Solvent 70-60 Carbon Black Pigment 0.5-5.0 PVC Stabiliser 0.1-0.5 Air Release Agent 0.2-0.75 Film Release Agent 0.2-2.0 The method of the present invention provides the following advantages.
If flaws are detected, the coating is quickly and cleanly removable to permit of corrective action.
If no flaws are evident, the film acts as a protection again some physical damage and corrosion developing during storage and/or transit.
Because the film is dry and is not sticky, it does not collect dirt as do conventional oils.
Flaws not detectable by previously known means may be rendered detectable by the present method.
Articles coated with the coating may be conveniently handled during the inspection procedure since the surface is dry and not sticky.
When it is desired to remove the coating, it may be easily removed by peeling off.
The invention will now be described in more detail by way of example, with reference to the accompanying drawing which is a diagrammatic crosssectional view, not to scale, through part of an article during the performance of the method.
Referring to the drawing, an article to be inspected is indicated generally at 10 and has a surface 11 which it is desired to inspect to ascertain if any flaw, such as a flaw 12, is present. A block, or at least a dark peelable coating is sprayed onto the surface 11 by a conventional air fed spraying technique as is well known in the art of paint spraying. The coating material is of the following composition: % w/w P.V.C/P.V.A.Copolymer 16.50 Plastisiser 7.0 Silicone Oil 0.02 Solvent 73.93 Carbon Black Pigment 1.25 PVC Stabiliser 0.30 Air delease Agent 0.50 Film Release Agent 0.50 The material during and shortly after spraying is in relatively fluid state and flows over the surface to produce a film 13 which is 0.025 mm (0.001 inches) thick and having a smooth reflective surface 14 except in the region of the defect 12 where the film, as indicated at 15, follows the contour of the defect 12. The surface is then illuminated with white light, in the present example daylight, and the incident rays 16 of the light are reflected as reflected rays 17 towards the eye of an observer, positioned at 19 over the majority of the surface 14 but are reflected in a different pattern in the region 15 as indicated by the rays 18.
The observer, at a position 19, therefore observes the region 15 as dark or darker than the remainder of surface 14 and thus knows that there is a flaw in the surface beneath the region 15 of the film 13.
It is preferred that the inspection of the article is performed sufficiently long after the coating material has been sprayed onto the surface 11 for it to have dried, in the present example twenty minutes, and thus become non-fluid in order that handling of the article is facilitated.
After inspection, at least where the coating is completely dry, the film 13 can be removed by peeling, i.e. by the application of a tensile force in the direction of the arrow T to a free end part 20 of the film 13 which transmits a tensile force through the film to an adjacent part 21 of the film 13 still attached to the surface 11 so that the film 13 is stripped off by rolling back. The coating material is of course chosen so as to be sufficiently flexible and strong to permit of such peeling off.
Depending upon the configuration of the surface 11 under inspection, the whole of the film may be removed in one piece or in a number of pieces but the pieces will be of relatively large size generally qt least one piece covering between.50% and 100% of the coated area of the surface 11 and the remainder, if any, providing a piece or pieces covering at least 10% of the surface, although there may be at least one piece which cover less than 10% of the area.
If the inspection procedure has detected a flaw, then the film 13 may be removed soon after inspection to permit of remedying of the flaw. If no flaw is detected, then the film 13 may again be removed shortly after inspection or may remain in place to provide protection against physical damage and corrosion occurring during storage or transit.
Instead of the specific composition described above, the coating may have a composition lying in the ranges set out below: % w/w P.V.C/P.V.A. Copolymer 8-20 Plastisiser 3-8 Silicone Oil 0.01-0.3 Solvent 70-90 Carbon Black Pigment 0.5-5.0 PVC Stabiliser 0.1-0.5 Air Release Agent 0.2-0.75 Film Release Agent 0.2-2.0 Instead of the coating being coloured black, it may be coloured some other relatively dark colour by the use of an appropriate colouring agent or otherwise rendered reflective.
Although in the present example the surface has been illuminated with a continuous source of white light, it may be illuminated with visually detectable light of other wavelength or group of wavelengths or it may be illuminated with other radiation of a wavelength which is reflected by the coating but outside visually detectable wavelengths in which case a suitable detector would be provided in place of the eye of the observer. In all cases, the light may be applied continuously or strobed which it has been found, at least in the case of white light, aids detection of flaws.
The invention has particular application to the inspection of surfaces of dies or die parts, such as dies used for extrusion or stamping, although could of course be applied to the inspection of any surface.
The features disclosed in the foregoing description, or the accompanying drawing, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, may, separately or in any combination of such features, be utilised for realis ing the invention in diverse forms thereof.

Claims (21)

1. A method of inspecting a surface to ascertain if there are any surface flaws in the surface, comprising the steps of applying a coating in fluid state to the surface, permitting the coating to become non-fluid, observing the surface to ascertain the presence of any surface flaws and then removing the coating.
2. A method according to claim 1 wherein the coating is a peelable coating whereby the coating is removable by peeling the coating from the surface (as herein defined).
3. A method according to claim 2 wherein the coating is removable from said surface in at least one piece comprising at least 10% of the area of the surface from which the coating is to be peeled.
4. A method according to claim 3 wherein the coating is peelable off in at least one relatively large piece comprising between 50% and 100% of said area.
5. A method according to any one of claims 1 to 4 wherein the coating is applied in a liquid state.
6. A method according to claim 5 wherein the coating is applied by spraying.
7. A method according to claim 6 wherein the liquid is sprayed by conventional air feed, airless, or by aerosol spraying.
8. A method according to any one of claims 1 to 7 wherein the coating is in the form of a thin film, having a thickness lying in the range 0.0063-0.051 mm (0.00025-0.002 inches).
9. A method according to any one of the preceding claims wherein the coating is opaque and of a dark colour.
10. A method according to claim 9 wherein the coating is black.
11. A method according to any one of claims 1 to 1ZO wherein the coating has flow properties so as to provide said film with a smooth reflective surface thereon which conforms to the surface to be inspected, including any flaws therein so that a flaw is detectable by a different pattern of reflection resulting from a deviation in the surface of the film in the region of the flaw.
12. A method according to any one of claims 1 to 11 wherein the coating is illuminated with white light or with visually detectable light of a specific wavelength or range of wavelengths.
13. A method according to claim 12 wherein the coating is continuously illuminated during inspection.
14. A method according to any one of claims 1 to 13 wherein the coating is a polymer.
15. A method according to claim 14 wherein the coating is a polyvinyl chloride/polyvinyl acetate copolymer.
16. A method according to claim 15 wherein the polyvinyl acetate component of the copolymer comprises between 12% and 16% of the copolymer and has a K value lying in the range 40 to 60.
17. A method according to claim 15 or claim 16 wherein the polyvinyl. acetate component comprises 14% of the copolymer and has a K value of 47.
18. A method according to claim 15, claim 16, or claim 17, wherein the coating is of the following composition: %w/w P.V.C./P.V.A. Copolymer 81-20 Plastisiser 3-8 Silicone Oil 0.01-0.3 Solvent 70-90 Carbon Black Pigment 0.5-5.0 P.V.C. Stabiliser 0.1-0.5 Air Release Agent 0.2-0.75 Film Release Agent 0.2-2.0
19. A method according to any one of the preceding claims wherein the surface under inspection is a die or part of a die.
20. A method of inspecting a surface substantially as hereinbefore described with reference to the accompanying drawings.
21. Any novel feature or novel combination of features disclosed herein and/or shown in the accompanying drawings.
GB08521332A 1984-09-06 1985-08-27 Method of inspecting a surface for flaws Withdrawn GB2164161A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB08521332A GB2164161A (en) 1984-09-06 1985-08-27 Method of inspecting a surface for flaws

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB848422555A GB8422555D0 (en) 1984-09-06 1984-09-06 Inspecting surface
GB08521332A GB2164161A (en) 1984-09-06 1985-08-27 Method of inspecting a surface for flaws

Publications (2)

Publication Number Publication Date
GB8521332D0 GB8521332D0 (en) 1985-10-02
GB2164161A true GB2164161A (en) 1986-03-12

Family

ID=26288193

Family Applications (1)

Application Number Title Priority Date Filing Date
GB08521332A Withdrawn GB2164161A (en) 1984-09-06 1985-08-27 Method of inspecting a surface for flaws

Country Status (1)

Country Link
GB (1) GB2164161A (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2618894A1 (en) * 1987-07-28 1989-02-03 Shell Int Research Method for visually displaying the surface condition of the cylinders of an engine using liners or of the bore of an engine block
US5569342A (en) * 1993-02-16 1996-10-29 National Research Council Of Canada Method for preparing solid surfaces for inspection
EP1106992A1 (en) * 1999-12-01 2001-06-13 British Aerospace Public Limited Company Tape to detect surface blemishes
DE102012110699A1 (en) * 2012-11-08 2014-02-20 Bundesrepublik Deutschland, vertreten durch das Bundesministerium für Wirtschaft und Technologie, dieses vertreten durch den Präsidenten der BAM, Bundesanstalt für Materialforschung und -prüfung Method for active thermography for detectinf hidden defects and trobles in test specimen, involves heating colorless absorber layer by irradiation with electromagnetic radiation from absorbing wavelength range

Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1052475A (en) * 1964-02-28
GB933701A (en) * 1958-11-12 1963-08-08 Maxwell Pevar Method for inspection of autogenous welds
GB934116A (en) * 1961-05-10 1963-08-14 Rolls Royce Improvements relating to the examination or recording of flaws in a ferro-magnetic workpiece
GB964915A (en) * 1961-08-25 1964-07-29 Westland Aircraft Ltd Improvements in or relating to a method of inspecting inaccessible rigid or semi-rigid surfaces
US3504524A (en) * 1966-09-09 1970-04-07 Automation Ind Inc Method of thermal material inspection
GB1277864A (en) * 1969-12-01 1972-06-14 Knapsack Ag Production of glycerol acetates
US3826917A (en) * 1973-05-16 1974-07-30 Rockwell International Corp Reverse magnetic inspection method
GB1447966A (en) * 1975-03-05 1976-09-02 Zahnradfabrik Friedrichshafen Method of detecting cracks in the surface of workpieces
GB1466554A (en) * 1974-08-23 1977-03-09 Nederlandse Appl Scient Res Method for recording defects in surfaces
GB1588093A (en) * 1978-04-19 1981-04-15 Nii Metal Method for detecting surface and subsurface flaws in rolled metal products
GB2119518A (en) * 1982-03-24 1983-11-16 George Victor Crowe Flaw detection method

Patent Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB933701A (en) * 1958-11-12 1963-08-08 Maxwell Pevar Method for inspection of autogenous welds
GB934116A (en) * 1961-05-10 1963-08-14 Rolls Royce Improvements relating to the examination or recording of flaws in a ferro-magnetic workpiece
GB964915A (en) * 1961-08-25 1964-07-29 Westland Aircraft Ltd Improvements in or relating to a method of inspecting inaccessible rigid or semi-rigid surfaces
GB1052475A (en) * 1964-02-28
US3504524A (en) * 1966-09-09 1970-04-07 Automation Ind Inc Method of thermal material inspection
GB1277864A (en) * 1969-12-01 1972-06-14 Knapsack Ag Production of glycerol acetates
US3826917A (en) * 1973-05-16 1974-07-30 Rockwell International Corp Reverse magnetic inspection method
GB1466554A (en) * 1974-08-23 1977-03-09 Nederlandse Appl Scient Res Method for recording defects in surfaces
GB1447966A (en) * 1975-03-05 1976-09-02 Zahnradfabrik Friedrichshafen Method of detecting cracks in the surface of workpieces
GB1588093A (en) * 1978-04-19 1981-04-15 Nii Metal Method for detecting surface and subsurface flaws in rolled metal products
GB2119518A (en) * 1982-03-24 1983-11-16 George Victor Crowe Flaw detection method

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2618894A1 (en) * 1987-07-28 1989-02-03 Shell Int Research Method for visually displaying the surface condition of the cylinders of an engine using liners or of the bore of an engine block
US5569342A (en) * 1993-02-16 1996-10-29 National Research Council Of Canada Method for preparing solid surfaces for inspection
EP1106992A1 (en) * 1999-12-01 2001-06-13 British Aerospace Public Limited Company Tape to detect surface blemishes
DE102012110699A1 (en) * 2012-11-08 2014-02-20 Bundesrepublik Deutschland, vertreten durch das Bundesministerium für Wirtschaft und Technologie, dieses vertreten durch den Präsidenten der BAM, Bundesanstalt für Materialforschung und -prüfung Method for active thermography for detectinf hidden defects and trobles in test specimen, involves heating colorless absorber layer by irradiation with electromagnetic radiation from absorbing wavelength range
DE102012110699B4 (en) * 2012-11-08 2019-05-09 Bundesrepublik Deutschland, vertreten durch das Bundesministerium für Wirtschaft und Technologie, dieses vertreten durch den Präsidenten der BAM, Bundesanstalt für Materialforschung und -prüfung Method and kit for active thermography

Also Published As

Publication number Publication date
GB8521332D0 (en) 1985-10-02

Similar Documents

Publication Publication Date Title
JP3401253B2 (en) Automotive exterior laminate with pressure sensitive adhesive
US3504524A (en) Method of thermal material inspection
DE3852759D1 (en) METHOD FOR EVALUATING SMOOTH SURFACES.
US5184190A (en) Method and apparatus for detecting flaws and defects in heat seals
GB2164161A (en) Method of inspecting a surface for flaws
DE10301931A1 (en) Floor and wall coverings defect detection method in which, in addition to a color camera inspection system, an additional short wave camera detection system is used to detect errors in the transparent protective layer
US7462809B2 (en) Spectral filter system for infrared imaging of substrates through coatings
DE3688547D1 (en) &#34;DIFFRAKTOSIGHT&#34; PROCESS.
JPH08309262A (en) Method and apparatus for measuring film thickness of golf ball coating film
Hue et al. CMO YAG laser damage test facility
JPH09269296A (en) Sheet coating defect inspection device
EP2087336B1 (en) Method for the detection of impurities on a surface
JPS5786743A (en) Grease measuring device
Miyagi et al. Study of peeling properties of pressure-sensitive adhesives using a newly developed image processing system
DE59601257D1 (en) Process for the detection of layers on metallic surfaces in printing machines
DE102004025490A1 (en) Optical measurement of reflective or transparent objects using laser, by applying e.g. condensate film that can be removed without contact
JP3340312B2 (en) Surface defect inspection equipment
US9864112B1 (en) Conformable retroreflective graphic film
Ruhemann Criteria for distinguishing additions from original paint
JP2001270065A (en) Decorative sheet
JP5536979B2 (en) Roll mill roll cleaning endpoint inspection equipment
CA2095154A1 (en) Method and Apparatus for Classifying Articles According to Their Color
JPH0882600A (en) Measuring method of reflectance of plastic film
JP3234992B2 (en) Blurring method of defective part in hydraulic transfer printing
JPH0599603A (en) Sensor for measuring amount of indentation of rubber member and measuring apparatus using the sensor

Legal Events

Date Code Title Description
WAP Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1)