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Rough forming:
The balls are formed into rough spheres on cold heading, hot forging, or hot rolling machines. |
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Flashing:
The balls are ground under pressure between rotating grooved cast iron plates to improve sphericity. |
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Heat treatment:
The balls are through hardened by heating to 840 ℃ and quenching. They are then tempered to remove excess stresses. |
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Hard’ Grinding:
The hardened balls are then ground under pressure between a rotating grinding wheel and a stationary cast iron plate. |
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Finish lapping:
The balls are carefully lapped to their final dimensions between grooved cast iron plates, one rotating and one stationary. |
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Inspection:
Varies according to grade from 4% AQL for commercial grades to 100% electronic scan and crack detecting for high precision. |