Technical Knowledge Database

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Welcome to the Weldability Sif Technical Knowledge Database. We frequently answer technical questions while assisting customers with selecting and using our products in their applications. You can search these questions using the form below.

A selection of recent questions and their answers:

Sif offer several options of filler materials, depending on desired results. Your biggest challenge with Cast Iron is preventing cracking during cooling. Due to the gain-structure of Cast Iron there are lots of fissures to fill with the consumable, and this often involves “peening”, hitting with a hammer, on less ductile filler rods. Suitable Sif brazing alloys – SifSilCopper 968 and Sifphosphor Bronze 8 – are more ductile and therefore flow into the fissures better without peening, adhering and cooling more consistently and avoiding separation cracks. But these are brass/bronze in colour, so the repair is very visible.

For colour-match and matching of mechanical properties, the best method is to use Super Silicon No 9, which can be utilised – without flux – in TIG, by grinding a 4mm No9 rod into a point on a bench-grinder. That point will then melt into the weld-pool. This is the method preferred by many professional Cast Iron restorers.

And finally, where you prefer to weld, not braze,, are happy to peen, and want to use a TIG rod that feels more familiar, then a CuNi rod, like SifAlloy No73, 30% Nickel, can be used. Colour difference will be noticeable, and the deposit will be less ductile, but higher strength.

For the last 2 options, pre-heating the component to “hand-hot”, 50-60C, and controlled-cooling after welding is recommended, to avoid cracking. Cooling can be better controlled by wrapping the component, or at least the joint, with a medium-duty welding blanket.
The replacement tig welding filler rod for Sifalumin No 36 is Sifalumin No 16.
The mig torch is directly wired, this will use mini torch liners, which are made from Teflon.
TWN742412 is a 0.6 - 0.8mm liner for the Mig 150.
TWN722077 is a 0.8 - 1.0mm liner for the Mig 180.
Without knowing the exact type/grade of bronze I can only advise our most accommodating alloys for welding of bronze with TIG or Oxy/Acetylene. If you wish to fusion weld bronze in oxy/acetylene, our Sifbronze No1 is the most widely-used alloy. Use Sifbronze Brazing Flux FO010050 for best results when welding bronze. Flame setting is important, as is welding speed. With TIG, Sifphosphor Bronze No8 is the alloy of choice for most bronzes. Flux is not required, but as with oxy acetylene cleanliness is paramount to success.
Rod to use would be Sifalumin No.27 if the joint is not structural with no strain on it.
PAT testing doesn't apply to industrial equipment. A welding rod quiver is not a consumer product and therefore is exempt from the requirement to be supplied with a plug. As there are a range of plug types that could be fitted to a quiver eg 3-pin or BS4343 etc, depending on what power supply it will be used with, it is customary to leave it to the distributor/end-user to determine and fit their required plug. This is the same convention as used with welding machines, lathes, presses and other industrial equipment.
Materials can be welded using Sifalumin No.15 and also Sifalumin No.16
Disclaimer: This information is provided 'as is' and we accept no responsibility for the accuracy or validity of this information.