LSE

HI
In copper enamelling process;
1- what is LSE (Low stress elongation)?
2- Is it better LSE be low or high?
3- How can we reduce the quantity of LSE in enamelling copper wire process?
4- What parameters in drowing and enamelling process on LSE?

Thanks

The ASTM has this to say about LSE:
ASTM B279

Significance and Use


3.1 This test method is designed as an inspection or acceptance test of new bare soft square and rectangular wire intended for subsequent fabrication into magnet wire.

Note 1—Since the applied unit stress and the time of application are constant for all wire sizes, the test enables comparisons of stiffness to be made between wires of the same or different size on the basis of the permanent elongation resulting from the application of a low unit stress.

1. Scope

1.1 This test method, known as the low-stress elongation (LSE) test, covers the procedure for determining the stiffness of bare soft square and rectangular copper and aluminum wire in terms of the permanent elongation resulting from the application of a tensile stress.


1.2 The SI values for the mass of the specimen are regarded as the standard. For all other properties, the inch-pound values are to be regarded as standard and the SI units may be approximate.

2. Referenced Documents (purchase separately)


LSE is a bare wire test of stiffness. The test is desinged so that it provides a reference from one size to another. I would think that the LSE value you would want would depend upon the stiffness you wanted. A low LSE would be a very stiff wire wihle a higher LSE would be a wire that was softer. Wire that was too stiff might fail the springback test.

During the enamelling process you generally pass the wire through a pre-annealer and then there is contin ued annealing in or during the enamelling process. Softer or annealed wire would normally elongate more than wire that was not annealed.

I assume you mean drawing; As the wire is drawn it is work hardened which would increase tensile strength and the wire would be stiffer. The LSE would be lower. During enamelling you would be annealing the wire and therefore the LSE should increase but since LSE is a bare wire test, you probably would not test for LSE. You might test for springback.