Copper is one of the most ancient metals in history, as it was first mined in the Balkans around 6000 BC. Moreover, it is the only metal that can be found naturally in the earth's crust.
It's a soft, durable, and malleable metal. It is a very versatile material that has been in use for several thousand years. It's been used to create everything from jewelry to weapons and plumbing since the beginning of civilization. For example, copper tube, copper pipe, copper wire, cookware, jewelry, daily usable things, and many more.
Copper has a high thermal and electrical conductivity, which makes it perfect for use in construction and electrical applications. It is extremely versatile, durable, and has a corrosion-resistant layer. This amazing metal can be shaped into many different forms and is used for various purposes, some of which are not even known to many.
Since copper is popular and is a widely used metal, you need to make things with copper. As a result, you have to make copper joints. Various ways like welding, different type of soldering, brazing, and many more are available for it. But the most popular and excellent one is the brazing of copper.
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What is the Brazing of Copper:
Brazing is a welding process that joins two pieces of metal of copper or brass with a filler metal called brazing alloys. A brazing rod is used to create a fusion between the pieces of copper that are being joined together. Brazing can be done in a variety of positions, including flat (horizontal), vertical, or overhead.
Brazing is a popular choice for joining metal items together, particularly in the automotive and construction industries. It’s especially useful for joining dissimilar metals.
Brazing copper is a common method and reliable alternative to traditional soldering. It is a versatile way to join copper pipes, copper fittings, and tubes. Brazed joints provide stronger joint than conventional solder joints as it creates a solid, inseparable bond between the parts and increases the joint strength.
Various types of brazing are available nowadays, such as manual brazing, vacuum brazing, diffusion brazing, dip brazing, fluxless brazing, automatic torch brazing, and many more. Whatever brazing applications you are choosing, you need to know how to do that brazing properly.
If you are also going to do brazing of copper for the first time, you might have some confusion and questions about it. But forget this distress. Because in this article we are providing you the most detailed guide about how to braze copper. So, dive into the article and execute your brazing journey perfectly.
Preparation is the key:
Before starting the brazing of copper, you need to make a good preparation to make the entire joint or execute the brazing perfectly. First, clean the metal surface properly. Check the base materials and filler materials so that you can know their melting temperature and arrange a proper temperature for the brazing jobs. Next, get proper flux and the accurate type of brazing rod. Thirdly, get all the safety equipment such as a full sleeve shirt and pant to cover all the skin possible, goggles to protect eyes, boots, shoes, and helmet. Then learn about the brazing process correctly, and you are good to do your first copper brazing.
How to Braze Copper:
Follow all the steps of the brazing process mentioned below. You must complete the braze joint job in one day, which means all the steps should be done on the same day. Now, if you are done with the preparations, start making the braze joint by following the steps:
- For the proper length, mark the tube.
- Cut the copper tube accordingly. You can cut it by using a tube cutter, hacksaw, or anything that can do the job. But the cutting process must be done accurately to the structure you want.
- Ream the brazing surfaces, which means the piece of cut tube for making the edge plane. For reaming, you can use any tool that will do the job. For example, you can use a reaming blade, a deburring tool, or a half-round file.
- Clean the metal surface to remove any kind of surface oxides or oils. You can use a rough pad or sand fabric. There should be a 0.004-inch space between the copper fittings and the tube.
- For creating copper alloys, enter the tube into the fittings. Make sure they are finely fit. Leave some space between them for the capillary action. It can be 0.0004 inches.
- Now, preheat the tube and fitting by using the flame. For this, hold it perpendicularly to them. The flame temperature depends on the melting temperature of the flux and the base metals. So, you can do low or high-temperature brazing accordingly. But, don't overheat, as overheating can burn the flux. So, don't hold the flame on any part of the tube and keep it in motion. Heat it consistently until the coating of flux becomes transparent.
- Connect the filler metal to the joint, which should start meting. Apply it to the place where the tube and fitting are connected. Apply the heat source to the mating surface when the filler metal completely melts. Put the solder somewhat off-center at the bottom if the joint position is horizontal. Now keep the torch at the base of the fittings and shove the solder into the joint straightly. The joint temperature will melt the filler metals. Note that you must keep the flame away from the filler metal. You can use the neutral flame and acetylene torches as it works great for very high brazing temperature. Stop the heating when you see a complete fillet.
- Now, put the braze joint for cooling down completely. But don't use any water for that. When it cools down, remove the excess flux with the help of a damp rag.
Things to Check While Brazing Copper:
- You must preheat the metal and flux. Get an idea about the brazing temperature you required.
- Get the flux, filler metal, and other things accurately. Most people prefer white flux paste.
- Put a space of 0.0004 inches between the tube and flux for thermal expansion.
- Don't use excess flux or extra layer of flux, and never use wetting of copper with water for cooling.
- Heat throughout the copper pipe.
Benefits of Copper Brazing:
- It increases joint strength and provides you strong joints. So, you can get structural strength.
- You can use this metal-joining process on dissimilar metals.
- This joint is used for operating even greater than 350 degrees.
- It gives high-temperature strength and also offers a corrosion-resistant layer.
- The process is easy, and the outcome is great than soldering.
Overall, copper brazing is a great way to get a strong joint and have structural strength. But to get a strong and clean joint, you must follow the brazing process correctly, use proper temperature, proper brazing filler metal, and flux. So, follow all the steps correctly and be an expert in copper brazing.
Frequently Asked Question (FAQ):
- Can copper and stainless steel be brazed or soldered together?
Yes, they can be brazed or soldered together. The metal-joining process is almost the same as copper to copper solder joints or braze. You just need to get the perfect filler metal and proper flux. Also, you need to be extra careful while working with stainless steel.
- When to use flux?
For brazing and soldering, you have to use flux. For soldering, use the needed layer of flux. And, for brazing, flux is compulsory. Try to use the flux that has silver content. The higher the percentage of silver is, the stronger the joint becomes. One of the most popular fluxes is white brazing flux. But never use excess flux for both soldering and brazing.
- Can I braze copper with a propane torch?
You can do it but won't get a good result because a propane torch is good for heating; it's not enough for brazing. You required 1100 to 1500 degrees of temperature for brazing, which a propane torch can't provide perfectly.
- Is brazing stronger than soldering?
Yes, brazed joints are stronger than solder joints. Brazing increases joint strength and gives you a stronger joint than soldering.
- Do you need flux for brazing copper?
Yes, you need a coating of flux for copper brazing. The layer of flux depends on the metals you are using. Also, flux types depend on the metals you are using. The most popular ones are blue flux and white paste flux. We prefer flux with silver contents. You can use white flux paste as a beginner.