SHEET METAL FABRICATION TECHNICAL TIPS FOR SOLDERING Common Solder Alloys and Their Uses in Roofing Solder is a fusible metal alloy (combination of metals) used to join together metal work pieces which has a melting point below that of the work piece(s). Solder is a low-­‐melting alloy commonly based on lead and tin used for joining less fusible metals such as copper and zinc. Soldering Iron Types Alloys of lead (chemical symbol Pb) and tin (chemical symbol Sn) have been universally used in the past, and are still readily available; they are particularly convenient for hand-­‐soldering. The tin/lead solders or “soft solder” is typically the materials that are thought of when solder or soldering is mentioned. These soft solders have a typical melting range b etween 90 and 450 °C (190 to 840 °F). They are commonly used in electronics, plumbing, and assembly of sheet metal parts. STANDARD SOLDERING IRONS USE LP GAS, IGNITE MANUALLY WITH A STRIKER AND CONNECT WITH A STANDARD POL CONNECTION TO ANY DOT PROPANE TANK OR WITH A WORTHINGTON REGULATOR TO ANY WORTHINGTON TANK Tin/lead solders are commercially available with tin concentrations between 5% and 70% by weight. The 63/37 lead/tin alloy is most commonly used for roofing work in Europe, the 50/50 alloys are more common in North America. Both alloys a re “eutectic alloys” which means: •
They have lower melting points, between 360 and 370 °F and •
The melting point is truly a point — not a range PREMIUM IRONS USE LP GAS, HAVE A BUILT IN PIEZO IGNITERS AND CONNECT WITH A STANDARD POL CONNECTION TO ANY DOT PROPANE TANK OR WITH A WORTHINGTON REGULATOR TO ANY WORTHINGTON TANK When a higher proportion of lead is used (67/33 versus 50/50) the higher proportion of lead creates the advantage of making the alloy solidify more slowly, so that it can be “wiped” over the joint to ensure water tightness, the joints being physically fitted together before soldering. The greater the tin concentration, the greater the solder’s tensile and shear strengths. Higher proportions of tin—more expensive than lead, also improve the wetting p roperties of the alloy as lead itself has p oor wetting characteristics. SELF C ONTAINED PREMIUM IRONS U SE A PROPANE/PROPENE GAS MIXTURE, HAVE A BUILT IN PIEZO IGNITER AND A SMALL PROPANE/PROPENE GAS CANISTER IN THE HANDLE
SHEET METAL FABRICATION TECHNICAL TIPS FOR SOLDERING Common Solder Alloys Common Lead Solder Alloys Tin Description Other Pb75Sn25 75 25 Pb70Sn30 70 30 Pb68Sn32 68 32 Sn30Pb50Zn2
0
Sn33Pb40Zn2
8 50 30 40 32 Pb67Sn33 67 33 Crude solder for construction plumbing and roofing – more frequently used by Europeans than 50/50. Sn50Pb50 50 50 Ordinary solder for soldering of brass, coper and zinc. General purpose, for standard tinning and sheet metal work. More common in North America. Crude solders AKA "Plumber’s solder" for construction plumbing works, flame-­‐
melted. Used for soldering car engine radiators. Also used for machine, dip and hand soldering of plumbing fixtures and fittings. Superior body solder (auto) 20% Zinc Zinc containing solders ( such as Kapp Galvrepair®) are economical solders for repairing & joining most metals including Zinc, Galvanized Steel, Galvanized 28% Zinc Aluminum, Aluminum and cast Iron. Lead-­‐free solders Lead-­‐free solder is somewhat less convenient for hand-­‐soldering and is often used to avoid the environmental effect of lead. Lead Free Solders for roofing are typically a minimum of 95.5% Tin with small amounts o f S ilver, A ntimony a nd/or C opper. The reason lead free solders have been introduced into the roofing industry is that the electrochemical couple of copper and lead promotes corrosion of the lead. Since even small amounts of lead have been found detrimental to health, lead in solders can be replaced by silver or antimony, often with small amounts of copper included. When using lead free solders, be aware that these solders are prone to forming microscopic cavities in the solder called “Kirkendall voids”. When two different types of metal that are in contact are heated, dispersion of the soldering metal occurs (called the Kirkendall effect). Repeated thermal cycling causes the formation of voids which may lead to solder cracks. Lead-­‐free solders can lead to shorter life cycles of the finished products. For questions or comments, contact us at www.guilbert-­‐express.com/contact.