Upgrade/RFFoil/WoodsMetal
Wood's metal is an allay with a low melting point, about 60 degrees C. A lot of information on Woods metal can just be found on WikiPedia:
http://en.wikipedia.org/wiki/Wood%27s_metal
Wood's metal contains cadmium and lead, and therefore is poisonous. However, there are a variety of alloys with similar low melting point that do not contain cadmium.
A few things that I found so far (September 2014)
- non-toxic are field's metal (62 C) and cerrolow 136 (58 C)
- cerrosafe (74 C) is said to be specifically suitable for machining: this is probably because on solidification is first shrinks a little and then slowly expands again. after 1 hour it has almost exactly the same size as in the molten state
- cerrobend (basically Wood's metal) expands on solidification by about a factor 1.006
- solid field's metal has a thermal expansion coefficient that is very close to Aluminum (22 x 10^-6)
Where to buy
Wood's metal is sometimes sold under the name 'Cerrobend'. Mari form VDL pointed us to these companies:
- http://www.hitechalloys.com/hitechalloys_002.htm
- http://www.boltonmetalproducts.com/Specifications.html
- http://www.lowdenlimited.co.uk/
For Field's metal I found this company:
http://www.rotometals.com/SearchResults.asp?Search=fields+metal
In the end we have ordered from Lowden Limited 1kg of Fields metal and 1 kg of Cerrolow 136. These are less toxic.
How to decide on what to use?
Cerrolow 136 is about half the price of Field's metal.