copper has a high heat depostion rate.....what current is recommended for 1/4 plate? dcep dcen?
As the other poster said copper has a very high thermal conductivity. You would use straight polarity DC tig and high amps for 1/4 at least 250 or higher. You will toast your self when doing it as the heat coming back off the copper that thick is unbearable. You had better have a good water cooled tig torch and some thick gloves also. You would want to weld it in a well ventilated area (you don't want to breathe the copper fumes). AC can do it but it is difficult to get enough heat into the 1/4 copper on AC You would have to be up around 300 - 400 amps and would have to have a huge tungsten. I have welded .120 (~1/8) copper sheet at 200 amps dc straight polarity (3/32 tungsten) with no problems. You could preheat the copper with a torch (~ 500F) and possibly weld it at lower amps. Be careful and anyone in the welding area should have proper protection - eye, skin, hands, and so on.
Not sure what you mean high heat depostion rate?? Copper, depending on alloy, has very high thermal conductivity so it does require a high heat input for welding. As fas as specifics, it depends on gage of the stock (1.4 thk plate), it depends on exactly what Cu alloy you are talking about, and it also depends on the type and details of the weld joint. Regardless of the recommended settings, unless your welder is highly experienced with TIG on Cu (in which case you probably would not need to be asking this question), it would be wise to have some scrap parts to practice on before attempting the actual assembly. This is particularly true if your assembly is complex, expensive, or if the performance of the welded joint is particularly critical (like the lives of an airplane full of people depend on the strength of the weld). In this latter case, consult with your local FAA representative.
