The process of coiling wire causes the wire to take on a curvature from the process of being mechanically deformed into a coiled geometry. The curvature in the wire is permanent unless the wire is straightened. It will affect how the coiled wire will react when it is subjected to additional wire forming operations. In addition, residual stresses induced from the coiling operation can cause elastic recoil or spring back in subsequent wire forming operations unless the material is straightened and stress relieved prior to forming. These residual stresses can create wide variations in the dimensions of components and or parts that have been built using the coiled wire (cast).

The direction that the wire has been coiled affects how the wire will be taken off of the coil for subsequent wire forming operations (helix direction).

Lift or spacing between adjacent coils also affects how the wire will be taken off of the coil and can also affect the dimensions of components and or parts that have been built using the coiled wire due to residual stresses (helix).

1.1 This test method covers the various standard methods that are used for measuring camber, cast, helix, and helix direction. The wire may be coiled with or without a spool.

1.2 This test method applies to round wire that has a diameter between 0.0127 to 4.78 mm (0.0005 to 0.188 in.). It also applies to flat or shaped wire.

1.3 This test method does not apply to superelastic nitinol wire. It does apply to the as-drawn condition of nitinol wire.

1.4 This test method does not apply to the measurement of the straightness of straightened to length wire and tubing.

1.5 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.

1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.