Automotive Brazing


The Original Sil-Fos

silfos, Lucas Milhaupt Silfos, best braze alloySil-Fos has been the preferred silver brazing alloy for HVAC/R contractors since it was patented in 1931. Sil-Fos alloys combine silver (Ag), copper (Cu), and phosphorous (P) to produce consistent, quality joints while saving on materials plus reducing time and process costs. 

Sil-Fos® alloys have become popular in the HVAC/R and plumbing industries because of the ability to join copper to copper without flux. No flux is necessary with Sil-Fos alloys; the phosphorous in the Sil-Fos family of products reacts with the copper oxides to form phosphorous pentoxide and cleans the surface. 

HVAC/R contractors have trusted Sil-Fos and Lucas Milhaupt for seamless, strong joints in the field for nearly ninety years.

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The History of Sil-Fos

silfos, history of silfos, Lucas Milhaupt SilfosFounded more than a century ago in 1867, Handy & Harman (HNH) had long been recognized as a leading company in precious metal fabrication, processing and refining. In 1931, (HNH) patented Sil-Fos, a silver brazing alloy. When designed and brazed correctly, joints brazed with SilFos will exhibit strength higher than that of the parent materials, often leading to failure in the base metal before the joint itself.

Sil-Fos: The Brazing Alloy of World War II

Then, war struck the world. Americans bought war bonds, committed to victory gardens, and contributed to the war effort however they could. We saw an opportunity to support the war effort by releasing the patent for Sil-Fos; we produced over 240 million ounces of silver for defense needs. 

Sil-Fos, Easy-Flo and other brazing alloys were used innumerable braze joints of planes, ships, and ammunition. Sil-Fos was instrumental in increasing the strength of airplane engine bearings and increasing engine efficiency, resulting in larger, faster airplanes.

The biggest contribution Sil-Fos offered was in machine repair. A broken or damaged metal shaft, bearing or gear could put a vitally-needed machine tool out of production. Replacement of the part might take as long as síx months under wartime conditions. But in many instances, the part could be repaired with the use of a Sil-Fos brazing alloy, and the machine restored to production in less than an hour.

Sil-Fos Today: The Best Braze Alloy in HVAC/R

best braze alloy, best braze alloy in HVAC/R, silfosLucas Milhaupt and Handy & Harman joined forces in 1967, and became a global leader metal joining solutions. Today, Lucas Milhaupt offers all of the product and process innovation in Handy & Harman tradition, while developing new and innovative brazing preforms and metal fabrication processes.

Sil-Fos is still the premier braze alloy solution for HVAC/R Contractors, and continues to be the best solution for strong, flux-free brazed joints on the market. Learn how to Select a Sil-Fos Alloy for your application or browse our Sil-Fos products