Plumbing Brass and Copper | Carbide Tool Tips
| Stainless Steel and Copper Saucepans
manufacturer of a simple plumbing fitting (brass fitting
to 16mm copper pipe) was experiencing a 4% leak rate
on newly brazed parts. The average production rate was
6000 parts per month and this was causing concern.
brazing was carried out on a hand operated, fixed burner
shuttle machine, brazing 6 components on about a 2 minute
cycle. The brass fittings were placed onto jigs and
the copper tube fitted. A 6% silver-copper-phosphorous
ring was placed over the tube and flux paste applied
using a paintbrush.
suggested that inconsistent fluxing was causing the
high leak rate. It was felt the fitting in position
1 had too much flux, whereas the fitting in position
6 had too little. The fittings were numbered and brazed
in the normal way for one week. The results showed that
of those fittings that leaked 80% were from the first
position and 20% from the sixth position.
carried out tests using braze paste with an alloy of
copper-tin-phosphorous until we found a grade that gave
good results. Due to the timed dispensing system and
the fixed flux to metal ratio of the paste, the same
amount of flux and braze alloy were applied to each
fitting giving a more consistent joint and therefore
significantly reducing the leak rate. Six years after
we started to supply this customer the line foreman
retired and we asked him what the leak rate had dropped
to, as we had received no figures. He told us that there
had only been 15 parts in that time.
we saved the company the costs involved in re-brazing,
the cost of 6% silver and cleaned up the brazing area
due to the controlled application of the flux.
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