Low-Cost Stator Material M734 Alternators

The M734 multioption mortar fuze employs an air-driven alternator to power the fuze electronics and to furnish a mechanical arming signature. The stator of the alternator is fabricated from an expensive high-nickel-content steel, Permalloy, costing 6.00 per pound. The two-piece stator is stamped in production quantities from progressive dies. A product improvement program was initiated to find a lower cost substitute stator material from the silicon steel family costing only 0.50 per pound. The program results showed that the nickel- coated M-36 silicon electrical steel is a suitable substitute for the Permalloy presently used in the alternator stator with respect to gun ruggedness, electrical output in flight, corrosion resistance, and voltage and frequency parameter adjustment. However, differences in stamping and drawing properties from those of Permalloy affect the end-plate and housing contact surface and the ability to draw the cup that contains the bearing. These diferences required corrective assembly procedures. To eliminate this corrective assembly, production dies must be developed that allow for the stamping and drawing properties of the electrical steel. The cost of developing these dies could be amoritized during a mobilization, but is not warranted with the production buys now anticipated. The cost and time to develop these dies are not compatible with the present production schedule. However, this material should be considered as a substitute material in the event of a mobilization base action.