Soldering Aluminium – A Quick Guide

Lots of people seek out for this information. What is the right method to solder aluminium parts? They want to know , how soldering an aluminium differs from joining regular metals, what type of soldering iron needs to be used, what’s the optimal temperature that suits the best for this type of process?

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We tried to cover these frequent questions in this article and provide useful insights into the same. Hope you will find the article useful.

Begin with Your Purpose

What you want to solder? Do you want to solder aluminium to copper? Do you want to solder an aluminium sheet? Selection of required materials needed for soldering process would largely depend upon your requirement itself.

Make sure that you have all the needed soldering accessories for the process.

Tips – Aluminium Soldering

The most widely soldered aluminum will comprise less than 1% of magnesium or 5% of silicon. Alloys with more amounts of these elements have weak flux wetting natures. High zinc and copper alloys tend to have weak soldering features due to speedy solder penetration & damage to base metal properties.

Design of Joint

The joint design which is used when soldering aluminum assemblies tend to be identical to those that are used along with additional metals.

The most regularly used designs are simple lap & T-form joints. Joint clearance may vary with the particular soldering technique, solder composition, base alloy, flux composition & joint design employed.

Nevertheless, as a guide, joint clearance that range from 0.005 – 0.020 in. (0.13 – 0.51 mm) will be essential when there is an use of chemical fluxes. A 0.002 – 0.010 in. (0.05 – 0.25 mm) space should be used when thereís a use of reaction type flux.

Joints should fit comfortably, however not so comfy that the solder is not able to get inside the gap.

Aluminium Soldering – Preparation

Dirt, Grease as well as other foreign substances should be distant from the aluminum surface prior to the soldering. The surface should be hygienic. A steel wool or stainless steel brush can work well. In many cases, simply solvent degreasing will be essential.

Nevertheless, if the solder surface gets heavily oxidized, chemical cleaning or wire-brushing might be essential.

Aluminium Soldering – CAUTION

Cleaners or caustic soda with pH level beyond 10 must never be used on alloys of aluminum or aluminum, since they might react chemically.

Area set using a stainless-steel wire brush in order to eliminate any oil/grease. Blowtorch should be used so as to heat base metal initially followed with melting Harbor Freight Alum weld Al Welding Rods

Aluminum Soldering – Techniques

The greater melting point solders generally used for joining aluminium assemblies in addition to the outstanding thermal conduciveness of aluminum show that a huge capacity heat source should be employed so as to bring the joint region to better soldering temperatures. Well controlled, uniform heating must be delivered.

Tinning of the surface of aluminum could be best done by wrapping the material using a molten solder puddle & then polishing the surface using a non-heat absorbing material like a serrated wooden stick, fiber block, or even a glass fiber brush.

Wire brush or any other metal substances should be avoided. They are likely to leave absorb heat, metal deposits and freeze the solder rapidly.

Solders

The salable aluminum solders could be classified in 3 major groups as per their melting-points:

Low Temperature Solder : The melting point of this solder can be 300-500 degree – F (149 – 260 degree C). A solder in such group will contain lead, tin, zinc, or/and cadmium & create joints with the minimum resistance to corrosion.

Solder with Intermediary temperature : It melts between 500 – 700 degree F (260 – 371 degree C). A solder in this group will contain cadmium or tin in different arrangements with zinc, in addition to small quantities of aluminum, silver or nickel, lead, and copper.

High temperature solder : This solder melts between 700 – 800 degree F (371 – 427 degree C). They contain 3 – 10% of aluminum & small quantities of other metals like copper, nickel, silver as well as iron to adjust their wetting & melting characteristics. The solders with high amounts of zinc tend to have the greatest power of aluminum solders & create the most corrosion-resilient soldered associations.

Rules – Aluminium Soldering

  • Before you start any type of aluminum soldering, clear the metal in order to eliminate any oils and grease
  • Joint fit should be snug however with an opening for the solder
  • Never allow the parts to move during soldering, this might result in weak results
  • See the manufacturers directions for the accurate volume of heat
  • Use appropriate flux

Additional Reading

8 Steps for soldering an aluminium – WikiHow
How to Select the Right Aluminium Solder – SolderDirect
How To Easily Join Together Aluminum Plates & Repair Aluminum Parts – YouTube Video