ASTM_F_2754_-_F_2754M_-_09_2013.pdf

Designation:F2754/F2754M09(Reapproved 2013)Standard Test Method forMeasurement of Camber,Cast,Helix and Direction of Helixof Coiled Wire1This standard is issued under the fixed designation F2754/F2754M;the number immediately following the designation indicates the yearof original adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.A superscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method covers the various standard methodsthat are used for measuring camber,cast,helix,and helixdirection.The wire may be coiled with or without a spool.1.2 This test method applies to round wire that has adiameter between 0.0127 to 4.78 mm(0.0005 to 0.188 in.).Italso applies to flat or shaped wire.1.3 This test method does not apply to superelastic nitinolwire.It does apply to the as-drawn condition of nitinol wire.1.4 This test method does not apply to the measurement ofthe straightness of straightened to length wire and tubing.1.5 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard.The values stated ineach system may not be exact equivalents;therefore,eachsystem shall be used independently of the other.Combiningvalues from the two systems may result in non-conformancewith the standard.1.6 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.2.Terminology2.1 Fig.1(a)through Fig.1(e)illustrate the physical mean-ing of cast,helix,direction of helix,and camber.2.2 Definitions:2.2.1 castthe maximum diameter of coiled wire when onecomplete circumference rests completely on a flat surface suchas a table,workbench,or floor.Fig.1(a).2.2.2 helixthere are two common methods for measuringhelixfree end lift and hanging helix.These definitions aredefined by Fig.1(b)and Fig.1(c),respectively.2.2.2.1 helix(free end lift)the maximum lift of the freeend of the wire when laid on a flat surface,Fig.1(b).2.2.2.2 helix(hanging helix)the maximum distance be-tween two adjacent coils of wire,Fig.1(c).Ahanging helix canalso be measured by suspending the coils.2.2.3 helix directioncan be left or right-handed depend-ing upon how the wire was coiled,Fig.1(d)2.2.3.1 left-handed helixthe wire is coiled in a counter-clockwise direction,Fig.2(a).2.2.3.2 right-handed helixthe wire is coiled in a clockwisedirection,Fig.2(b).2.2.4 camberthe deflection in the width direction of a flator shaped wire,Fig.1(e).3.Summary of Test Method3.1 The maximum diameter of at least one complete cir-cumference is measured using a linear scale while it is restingcompletely flat on a flat surface such as a table,workbench,orfloor(cast measurement).The maximum lift of the free end ofthe wire when laid on a flat surface is the free end lift helix andis measured using a linear scale.A hanging helix can bemeasured using a linear scale while the wire is being suspended(hanging helix free end lift).Camber is the offset in the widthdimension of a flat or shaped wire and can also be measuredusing a linear scale while the wire is resting on a flat surface.Alternatively,a coordinate measurement machine or opticalcomparator may be used.Helix direction is the direction whichthe wire has been coiled.4.Significance and Use4.1 The process of coiling wire causes the wire to take on acurvature from the process of being mechanically deformedinto a coiled geometry.The curvature in the wire is permanentunless the wire is straightened.It will affect how the coiledwire will react when it is subjected to additional wire formingoperations.In addition,residual stresses induced from thecoiling operation can cause elastic recoil or spring back insubsequent wire forming operations unless the material isstraightened and stress relieved prior to forming.These re-sidual stresses can create wide variations in the dimensions ofcomponents and or parts that have been built using the coiledwire(cast).1This test method is under the jurisdiction ofASTM Committee F04 on Medicaland Surgical Materials and Devices and is the direct responsibility of SubcommitteeF04.15 on Material Test Methods.Current edition approved Oct.1,2013.Published October 2013.Originallyapproved in 2009.Last previous edition approved in 2009 as F2754/F2754M 09.DOI:10.1520/F2754_F2754M-09R13.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 4.2 The direction that the wire has been coiled affects howthe wire will be taken off of the coil for subsequent wireforming operations(helix direction).4.3 Lift or spacing between adjacent coils also affects howthe wire will be taken off of the coil and can also affect thedimensions of components and or parts that have been builtusing the coiled wire due to