ASTM_D_7093_-_13.pdf

Designation:D709313Standard Test Method forFormability of Thin Film Organic Coatings on Steel Over aBiaxially Stretched Dome1This standard is issued under the fixed designation D7093;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method covers the evaluation of the formabilityand adhesion of factory applied thin film organic coatings onsteel with thicknesses of 2.5 to 10 microns(0.10 to 0.40 mils)typical of those used in the coil coating industry.1.2 The degree of oil removal prior to forming,the tech-niques of taping,and differences in adhesive strength of thetape can affect the adhesion rating.1.3 The values stated in SI units are to be regarded as thestandard.The values given in parentheses are for informationonly.1.4 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.For a specifichazard statement,see Section 7.2.Referenced Documents2.1 ASTM Standards:2D3330/D3330M Test Method for PeelAdhesion of Pressure-Sensitive Tape2.2 Other Document:Pictorial Standards of Coating Defects33.Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 dome height,nthe height of the dome formed in thetest.3.1.2 indenting ball diameter,nthe diameter of thespherical-ended penetrator(ball)used to deform the specimen.3.1.2.1 DiscussionThe 41 mm(158in.)diameter ball wasselected because it minimizes the variability in the localizedpeak strain.This size ball is commercially available and is aslarge as most testing machines can accommodate.3.1.3 percent strain,nthe percent elongation of scribedgage lengths after forming.3.1.3.1 DiscussionFor the draw height of 13 mm(0.512in.),using a 41 mm diameter ball,the localized peak strain isabout 19%(see Fig.1).4.Summary of Test Method4.1 A coated specimen is biaxially stretched a given dis-tance in an appropriate machine,adhesive tape is applied to thedeformed area(dome)and then pulled off,and the amount ofcoating removed is compared with a photographic standard todetermine the coating adhesion rating.5.Significance and Use5.1 The results of the combined deformation and tape testare related to the ability of the coated metal to withstandstamping in factory applications.5.2 This test can be used to control the manufacturingprocess or in development work to improve the product.5.3 It should be recognized that variability in the resultspersist due to the test conditions and forming machine varia-tions.6.Apparatus and Materials(see Fig.2)6.1 Forming Machine,equipped with a spherical-endedpenetrator to deform the specimen with appropriate dies,untilthe required height is obtained,and clamping arrangement tohold the specimen with a minimum pressure of 8.9 kN(2000lb).6.1.1 The speed of forming shall be between 4.8 and 25mm/min(0.2 and 1.0 in./min).The speed is usually slowed tomeasure more accurately the final height as shown on the dialindicator,but the final punch speed shall be controlled at 6 mm(0.24 in.)per min maximum.1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings,Materials,and Applications and is the direct responsibility ofSubcommittee D01.53 on Coil Coated Metal.Current edition approved June 1,2013.Published July 2013.Originally approvedin 2004.Last previous edition approved in 2004 as D7093 04 which waswithdrawn January 2013 and reinstated in June 2013.DOI:10.1520/D7093-13.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3Copies of the pictorial photographic reference standard are contained in thepublication Pictorial Standards of Coatings Defects and may be obtained from theFederation of Societies for Coatings Technology,492 Norristown Rd.,Blue Bell,PA19422.The silver halide gelatin photographs are intended to be the only primaryreference standards for this test method.The reproductions of them in this testmethod are for the purpose of illustration only.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 6.2 Indenting Ball,with a diameter of 41 mm(158in.),aRockwell hardness number not less than 61 on the Rockwell Cscale(HRC),and a smooth surface finish not exceeding 4 m(160 in.).The indenting ball shall not deform during the test.The ball and holder shall move through the centerline of the topand bottom dies.The ball shall be clean and free of oil,grease,oxide buildup,rust,dirt,nicks,or damage.6.3 Ball H