RECOMMENDATIONS

BAN OF CADMIUM IN BRAZING FILLER METALS RECOMMENDED ALTERNATIVES

Cadmium bearing brazing alloys have been banned in the European Union since december 2011 (EU Commission Regulation no. 494/2011) and their usage is no more allowed.
A full line of cadmium-free alternative alloys is available. Please see the attached table that provides you a guidance in the process of selecting the proper alternatives:

CD-CONTAINING ALLOY CD-FREE ALTERNATIVE ALLOY
ALLOY MELT. RANGE (°C) BEST EQUIVALENT MELT. RANGE (°C) POSSIBLE EQUIVALENT MELT. RANGE (°C)
Ag13Cd 605-795 Ag20 690-810
Ag17Cd 620-760 Ag20 690-810
Ag19Cd 630-730 Ag25Sn 680-760
Ag20Cd 620-750 Ag25Sn 680-760 Ag20 690-810
Ag21Cd 620-730 Ag30Sn 665-755 Ag25Sn 680-760
Ag25Cd 605-710 Ag34Sn 630-730 Ag30Sn 665-755
Ag30Cd 610-690 Ag40Sn 650-710 Ag34Sn 630-730
Ag34Cd 610-670 Ag45Sn 640-680 Ag38Sn 650-720
Ag38Cd 610-650 Ag45Sn 640-680 Ag40Sn 650-710
Ag40Cd 595-630 Ag55Sn / Ag56Sn 630-660 / 620-655 Ag45Sn 640-680
Ag42Cd 605-620 Ag56Sn / Ag55Sn 620-655 / 630-660 Ag45Sn 640-680
Ag45Cd 605-630 Ag56Sn 620-655 Ag55Sn 630-660
Ag50Cd 620-640 Ag56Sn 620-655 Ag55Sn 630-660
Ag50CdNi 635-690 Ag49MnNi 680-705

Cadmium-free alloys are available in a wide range of compositions for different applications. They are free-flowing, ductile and strong and generally require higher brazing temperatures than do cadmium-bearing alloys.

Should you need further advice, information, or technical data, please feel free to contact us: our commercial and technical staff will help you select the most appropriate cadmium-free substitutes.

STEPS FOR A SUCCESSFUL BRAZING

1. Ventilation
Ensure there is sufficient ventilation: brazing operations should never be undertaken in confined areas or if there is not enough ventilation.
2. Joint gap
Ensure that, at brazing temperature, the brazing joint will have the proper clearance (for “in air” brazing with flux, proper gaps range normally from 0,05 to 0,20 mm).
3. Pre-braze cleaning
Carefully and thoroughly clean the pieces to be brazed: joint surfaces must be free from any contaminant, such as oil, lubrificants, dust, grease, etc.
4. Fluxing
Apply a proper quantity of flux on the pieces in order to protect the joint surfaces from oxidation (note: when brazing copper to copper with copper-phosphorous alloys, no flux is necessary).
5. Assembly and fixturing
Assemble the pieces and ensure that they will maintain position and alignement during brazing (fixturing may be needed).
6. Heating
Heat evenly and uniformly the joint area, insisting more on heavier sections. Do not try to melt the filler alloy by directly directing the flame on the rod.
7. Brazing
As soon as the pieces reach the brazing temperature, feed the rod in the joint area and let it melt and flow. Capillary action will draw the molten alloy inside of the joint.
Avoid overheating, which might lead to damaged or deformed pieces, unsound joints, and emission of harmful fumes.
8. Post-braze cleaning
After brazing, allow the pieces to cool down and remove flux residues by washing in warm water, brushing, or other methods (chemical pickling, ultrasounds, etc.).