How to Braze Copper 101

Last Updated on May 17, 2022

Brazing is a method of combining two metals that uses heat to bond them together. As a bonding agent, it uses filler metal with a lower melting temperature than the metal to which it is attached.

Although this procedure is frequently confused with soldering, the two procedures are not identical. Brazing, as opposed to welding, is characterized by the melting of the workpiece. It also uses the heat generated by a flame rather than alternative methods. Because of the difference in temperatures between the two procedures, the first occurs at temperatures below 450°C, while the second occurs at temperatures exceeding this temperature.

Metals such as brass, copper, stainless steel, and ceramics are examples of those that can be used. Furthermore, as newer metals and service requirements are introduced, the range of available brazing alloys grows in size. Given their strength, brazed joints are frequently used on aircraft components, missiles, and rockets, among other applications.

Brazing must be performed in a vacuum to be effective; otherwise, the remaining air molecules would disrupt the process, weakening the connection that has been established. It is necessary to melt filler metal and dust it onto one surface, after which it is melted onto the other surface until both surfaces are plated with an alloy, allowing them to become similar metals that are bonded together. As a result, filler metals are being used to join two surfaces together.

The purpose of brazing copper together

Cupro-nickel brazing is a technique for increasing joint strength in systems that function at temperatures greater than 350 degrees Celsius. A copper pipe connector is used to join two or more copper pipes commonly found in plumbing installations. A certified plumber, on the other hand, would be required for this procedure, and the opportunity to braze a pipe is not one that comes along very often.

It is possible to join two lengths of copper tubing together by brazing them together, though this is not commonly done. If there are any remaining air molecules present, the process will be less effective, which should be kept in mind.

Brazing Copper – The best ways to do it

Copper is heated to a high temperature, and then a constantan layer (a metal with excellent heat conductivity and low electrical resistance) is applied over it. When heated to 250 degrees Celsius, if the two parts are perfectly aligned, they will fuse into a single entity. Small gas bubbles will rise to the surface of the metal as it heats up, and these can be punctured with a brazing needle before the procedure begins to prevent further damage. The flux prevents any small gas bubbles from damaging everything.

After the junction has been heated, apply a generous amount of solder paste over it; this will liquefy as the joint is heated again, thereby completing the connection! It may be necessary to use a flux-covered brazing rod in situations where constantan does not provide sufficient thermal conductivity or if you want to ensure that the temperatures of the two components are nearly identical before applying heat for the first time.

How to Braze copper – A step-by-step Guide:

  1. Make a note of the length of the tube you’re using as a reference.
  2. Hacksaw, razor, or whatever method you prefer to use to cut the tube will work well.
  3. Smooth the cut tube’s ends to eliminate all metal spikes that may have formed as a result of the cutting operation. If necessary, a blade, file, or deburring tube can be used to smooth the surface.
  4. You should clean any oxides or oil that has accumulated on the parts that you will be soldering in order to prevent them from soldering improperly. Finally, use a file in conjunction with any abrasive pad to complete the process. There should be a.004-inch gap in the middle of the tube and the connection point.
  5. Carefully place the tube into the fit as tightly as possible while leaving enough space for the solder to act as a capillary to function. The width is approximately.0004 inches in width and length. Toss the tube and support it with your entire body, if at all possible.
  6. Hold a flame parallel your tube and simultaneously heat both the pipe and the fitted cup to the proper temperature for the application.
  7. Make sure to avoid using too much heat, as this could result in the flux to burn. To complete this procedure, it is recommended that you make utilize an oxyfuel torch. Keep the torch moving over the tube’s section you want to braze so that the heat is distributed evenly throughout the tube. Be careful not to overheat any one section of the tube more than another. To eliminate as well as to dissolve oxides that may be present when adding flux, gloves should be worn. Use gloves or a pair of gloves when applying a flux. Touching sensitive body parts or broken skin should be avoided at all costs. In the process of brazing the tube (copper) into wrot copper fits with BCuP brazing alloys, you may make use of a brazing flux; however, it is not required in the vast majority of cases in most situations. Maintain a consistent temperature until the liquid clears up. (It is important to remember that maintaining a consistent tube temperature possessing a larger diameter is more difficult.) It is necessary to preheat the entire installation. Another torch may be used to assist in maintaining the necessary heat. )
  8. When you apply pressure to the filler material in the junction, it should begin to melt. Put a small amount of sealant on the tube’s entry point into the connector. If you want to avoid melting these filler metals, direct the heat towards cup’s bottom instead of the top. It is recommended that the solder be placed a bit away from the center towards the bottom of a horizontal junction if the joint is horizontal. Maintain the torch’s position on fitting’s base and in front of the area where the soldering application will take place while you continue to push the solder into the connection directly. Maintain a safe distance between the flame and the present filler metals. The heat the joint generates should be sufficient to melt the present filler metals the joint uses. A very small amount of the fire must be present before applying filler metals. Vertical joints should be treated in the same way that horizontal joints should be treated: with caution. When the surface is completely plated, turn off the heat.
  9. Do not use any water to let this joint release heat naturally. After the flux has cooled, wipe it down with a wet towel to remove any remaining excess.