Process For Flux Coating Braze Preforms And Discrete Parts

Abstract

Systems and methods for evenly applying a flux coating to any number of different shaped parts with a single machine are described. The systems and methods provide advantages in that the flux coating may be applied accurately within 2% to 4% of desired thickness with 85% to 95% of the total yield of flux being applied, this minimizing waste. Thousands of parts may be batch treated with a single machine without operator input.

What is claimed is: 
     
         1 . A method of applying a flux coating on a plurality of parts for a brazing operation comprising:
 tumbling the parts in a tumbling drum with a controlled atmosphere including a user definable temperature and humidity within the tumbling drum;   cycling the parts through a coating cycle comprising:
 spraying a flux from at least one nozzle within the tumbling drum during the tumbling for a user defined period of time; 
 coating the parts with flux with a uniform thickness; 
 tumbling the parts following the user defined period of time to cure the flux to a desired hardness; and 
   repeating the coating cycle for a plurality of repetitions wherein the uniform thickness of coating on the parts is uniformly increased with each coating cycle.   
     
     
         2 . The method of applying a flux coating on a plurality of parts for a brazing operation of  claim 1 , further comprising providing an acrylic resin binder with an iso-butyl methacrylate polymer. 
     
     
         3 . The method of applying a flux coating on a plurality of parts for a brazing operation of  claim 2 , further comprising mixing polyethylene carbonate with the binder. 
     
     
         4 . The method of applying a flux coating on a plurality of parts for a brazing operation of  claim 1 , further comprising coating the parts up to 0.015 in (3.81 mm) thick while maintaining the uniform thickness within 2% of the total weight of the part. 
     
     
         5 . The method of applying a flux coating on a plurality of parts for a brazing operation of  claim 1 , further comprising spraying the flux from a nozzle with an opening of 0.05 in (12.7 mm) to 0.08 in (20.32 mm). 
     
     
         6 . The method of applying a flux coating on a plurality of parts for a brazing operation of  claim 1 , further comprising circulating the atmosphere within the tumbling drum with exhaust ducts. 
     
     
         7 . The method of applying a flux coating on a plurality of parts for a brazing operation of  claim 1 , further comprising adhering 85% to 95% of the sprayed flux to the parts. 
     
     
         8 . The method of applying a flux coating on a plurality of parts for a brazing operation of  claim 1 , further comprising agitating the parts within the drum with at least one agitator during tumbling. 
     
     
         9 . The method of applying a flux coating on a plurality of parts for a brazing operation of  claim 1 , further comprising spraying a sealant over the parts and flux. 
     
     
         10 . The method of applying a flux coating on a plurality of parts for a brazing operation of  claim 1 , further comprising setting the parts on a conveyor that transports the parts into an enclosure with a plasma cleaning chamber, a heating chamber, and an ultrasonic flux spraying chamber. 
     
     
         11 . The method of applying a flux coating on a plurality of parts for a brazing operation of  claim 10 , further comprising plasma cleaning the parts in the plasma cleaning chamber to remove contaminants allowing a proper adhesion of the flux coating to the parts. 
     
     
         12 . The method of applying a flux coating on a plurality of parts for a brazing operation of  claim 11 , further comprising heating the parts after plasma cleaning in the heating chamber to a desired temperature. 
     
     
         13 . The method of applying a flux coating on a plurality of parts for a brazing operation of  claim 12 , further comprising spraying the parts after heating in the ultrasonic spraying chamber with an ultrasonic sprayer configured to atomize a liquid flux solution and coat a single side of the parts with the flux coating and leaving an opposing side of the part free of the flux coating. 
     
     
         14 . The method of applying a flux coating on a plurality of parts for a brazing operation of  claim 10 , further comprising adjusting a speed of the conveyor to dry the parts to a desired moisture content. 
     
     
         15 . The method of applying a flux coating on a plurality of parts for a brazing operation of  claim 1 , further comprising spraying one of a metal and an alloy on the flux coated parts, thus eliminating a need for a filler metal application during a brazing procedure. 
     
     
         16 . The method of applying a flux coating on a plurality of parts for a brazing operation of  claim 1 , wherein the uniform thickness of the coating on the parts is within 2% of a desired thickness. 
     
     
         17 . A method of applying a flux coating on a plurality of parts for a brazing operation comprising:
 spraying a flux from at least one nozzle within a tumbling drum during a tumbling operation for a user defined period of time;   coating the parts with the sprayed flux with a uniform thickness;   tumbling the parts following the user defined period of time; and   curing the flux to a desired hardness.   
     
     
         18 . The method of applying a flux coating on a plurality of parts for a brazing operation of  claim 17 , further comprising:
 coating the parts with the cured flux up to 0.015 in (3.81 mm) thick; and   maintaining the uniform thickness within at least one of 2% of the total weight of the part and 2% of a desired thickness.   
     
     
         19 . The method of applying a flux coating on a plurality of parts for a brazing operation of  claim 17 , further comprising:
 mixing an acrylic resin binder with an iso-butyl methacrylate polymer with the flux; and   mixing a polyethylene carbonate with the binder.   
     
     
         20 . A method of applying a flux coating on a plurality of parts comprising:
 spraying a flux from at least one nozzle with an opening of 0.05 in (12.7 mm) to 0.08 in (20.32 mm);   tumbling the parts for a user defined period of time within a tumbling drum;   coating the parts with the sprayed flux to a uniform thickness;   curing the flux to a desired hardness by circulating an atmosphere within the tumbling drum with exhaust ducts;   maintaining the uniform thickness within at least one of 2% of the total weight of the part and 2% of a desired thickness; and   adhering 85% to 95% of the sprayed flux to the parts.