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Cold Rolled Steel Strip is Best for Measuring Tape Spring and Blade

As we know, spring and blade of measuring tape is thin, narrow flexile and hard. The surface blade is marked scale. Most manufactures of measuring tape would choose cold rolled steel strip for measuring tape spring and blade. Because the cold rolled steel strip is undertaken to reduce the thickness, improve the surface finish,improve the thickness tolerances, offer a range of "tempers",as a preparation for surface coating.

Cold rolled steel strip is normally by the Pickling Process which uses mechanical manipulation (around small diameter rolls) and acid to dissolve the surface scale. The surface is then washed to remove the acid and a light oil added to prevent rusting.

Most Cold Rollers, incorporate two rolling stations. The in initial cold rolling is undertaken on a more powerful "break down" mill that is capable of heavy reductions. The annealing involve to soften the steel, improve machinability, relieve internal stresses induced by some previous treatment (rolling, forging, uneven cooling) and remove coarseness of grain.After annealing to remove the stress and work hardening introduced in the process, the final cold rolling or "skin-pass" takes place. This is a light reduction (typically 3%) to improve the surface finish.

Cold rolling mills are typically  reversing mills. A reversing mill is where the steel enters the rolling mill from one side, passes through the other side and then comes back through the mill again. Normally it will go left to right through the mill a number of times being rolled a little thinner each time it goes through.

Cold rolled steel strips also can be produced in various conditions such as skin-rolled, quarter hard, half hard, full hard depending on how much cold work has been performed. This cold working (hardness) is often called temper, although this has nothing to do with heat treatment temper.

In skin rolling, the metal is reduced by 0.5 to 1% and results in a surface that is smooth and the yield point phenomenon excessive stretching and wrinkling in subsequent operations, is eliminated. This makes the metal more ductile for further forming and stretching operations.

Quarter Hard, Half Hard, Full Hard stock have higher amounts of reduction.Quarter Hard material is suit for measuring tape spring and blade. It can be bent (perpendicular to the direction of rolling) on itself without fracturing. Half hard material can be bent 90o; full hard can be bent 45 degree. Thus, these materials can be used for in applications involving great amounts of bending and deformation, without fracturing.

Classical Cold Rolled is produced on narrow strip mills typically offering widths up to 500mm with "close" gauge control and a wide range of sizes, qualities, hardness's and surface finishes. Links to Service Centres dealing in classical cold rolled can be found here CR Service Centres.

On all accounts, Cold rolled steel strip is the best for measuring tape spring and blade.

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