Paste Brazing

Paste brazing techniques differ from the other types of brazing methods. However, the principle steps of brazing are similiar. These steps include joint design, the creation of a gap for capillary filling, surface sanitization of the metals and an appropriate heating technique. Conversely, paste brazing also requires the allotment of a special shoulder or ledge within the joint design so that the required amount of paste can be applied to the external mouth of the joint. If no ledge for the paste is present within the joint design, then the design must allow the paste to flow towards the orifice of the joint.

Bluewater utilizes furnace heating, resistance heating, hand torch heating, induction heating and fixed burners as acceptable heating methods for their paste brazing methods. The type of heating method we use is determined by the size of your components and your requisite production rates. Brazing pastes can also be applied in numerous ways. Bluewater’s facilities utilize positive displacement via applicator gun, pneumatic placement via syringe or cartridge and automated robot systems. These methods of applying paste via bead or continuous stripes are the most cost effective means of applying paste for brazing. Our technicians will help determine the most cost effective method based on the type of paste that is employed.

Like other brazing filler materials, different types of paste can be specially formulated that allow the paste to adhere to the component in a number of ways. Our archetypal brazing paste will consist of a metal powder, a flux and a binding agent that will hold the component parts in suspension so that the paste is readily available for brazing. We will formulate the appropriate paste dependent on your desired part characteristics. Flux residues leftover after brazing pastes can be corrosive and will need immediate removal after brazing has been completed. These impurities that are left behind can be removed the same way as other brazing methods, via hot water, sulphuric acid or grit blasting. Bluewater can help determine the best removal method based on your component parts and the type of flux used. Our technical team is always readily available to help meet any of your paste brazing needs.

Paste Brazing Properties

  • Paste can be dispensed in accurate and controlled volumes, ensuring a joint receives the same volume of paste throughout each application
  • Paste has several performance issues like slumping of the paste in vertical positions, reduction of volume due to binder burnoff, and carbon residues leftover on the parts
  • Pastes are suitable for a wide variety of joint configurations
  • Very cost effective when done correctly
  • Paste has an advantage over preforms because it can be rapidly applied to the joint area

Paste Brazing Applications

  • Types of paste brazing filler metals are: Silver, cadmium free silver, copper, nickel, nickel chrome and aluminum
  • For high-speed automated brazing operations where quick removal of tenacious surface oxides at high temperatures are required
  • For assemblies that require high-production runs

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