53 replies to this topic

[Bloggsworth]

To put out a Magnesium fire it needs to be completely smothered and starved of Oxygen – not easy to do without the right equipment. Water is useless as it only provides more oxygen which in turn feeds the fire.

 

Ah - The famous North Street conflagration...

Edited by Bloggsworth, 25 August 2013 - 19:51.

[Greg Locock]

Two stories

 

1) We ask an Australian high quality machine shop if they were nervous about machining mag castings- no, they segregate all their scrap and recycle it ( as it turned out their price for machining Ti was excellent precisely because their segregation was so good. Best vendor I ever dealt with). 

 

2) We ask a German gearbox manufacturer if we could have magnesium casings. "No, they are not affailable". "Why not?" "The factory-it burnt down". 

[PJGD]

I am familiar with that syndrome.  When I served my engineering apprenticeship in the mid 60's with Dennis Brothers in the UK building trucks, buses, and fire engines, the machine shops there were still overhead line-shafting belt-driven dark satanic mills.  Then one day enlightenment came and we got two brand new state-of-the-art NC milling machines and these were used to face off the top and end faces of the magnesium gearbox housing.  The two NC machines sat side by side along with their pin board controllers with each machine fixtured for a different task.  After shakedown and a few months of satisfactory work, Dennis were so proud of their leading edge machining capabilities that they invited the local chapter of the Society of Production Engineers to view the machines in action.  Unfortunately, pride comes before a fall.

 

The foreman "Harry" of the milling section was ex. D. Napier & Sons (came to us when they closed down at Acton) and so no stranger to a higher class of machining than typical in the truck business.  The NC machines were set up with a holding fixture at either end of the table and so as one housing was being machined, the finished housing was removed from the other fixture and replaced by the next housing.  Then the traversing table reversed and the operator moved to the other end.  There may have been a lesser regard for safety back then, I suspect.  Anyway, Harry was demonstrating the amazing wonders and magic of numeric control to the assembled throng but unfortunately he forgot to tighten down one of the clamps due to the distraction of simultaneously explaining what he was doing.  Of course, when the table reversed, the large face-cutter ran into the steel clamp and the resulting sparks lit off the magnesium swarf and then the two large gearbox housings on that machine and quickly moved on to the swarf and housings on the adjacent machine which were both sitting on old oil-soaked wood sett floors.  The resulting conflagration completely took out both of these new machines plus a goodly part of the machine shop thereabouts.  To add to the misfortune, all the fire extinguishers that anyone could find close by were either the wrong type or did not work.  All in all, there were many lessons to be learned on that sorry day.  Of course, the fact that we built fire engines was of little help either. 

 

PJGD

[gruntguru]

  Great story. Thanks PJGD.