To braze three joints on a dental prophy jet assembly with induction heating; to improve yield consistency and reduce cycle time.
Parts & Materials Description
Stainless steel prophy nose piece, two tubes, tube support collar, braze alloy rings, B1 flux
Induction Heating Equipment
1kW RF Power Supply, specially-designed inductor (coil)
Initial testing was done to establish time-to-temperature and heating profiles. It was determined that a two-stage process would deliver optimum results. For this application a specially designed four-turn, double-wound helical inductor was used to deliver even heat to the joint areas. The two tubes, tube support collar and nose piece were assembled and held in position with temporary fixturing. The braze alloy rings were placed in position and a thin coat of B1 flux was applied to the entire assembly. In the first stage of the heating process, the upper tube end of the assembly was placed in the heating zone and induction power was supplied for 10 seconds. In stage two, the assembly was reversed and the lower end of the assembly was heated for an additional 10 seconds. The assembly was then removed, bathed in hot water to remove the flux, and blown dry with hot air.
Consistent, repeatable results were obtained with with the 1kW power supply and 10 second heat cycles. Each braze joint was sealed with an even filet of braze alloy.