Material: magnesium
Tools: 1/8 two-flute carbide end mill (First roughing pass) 1/16 two-flute carbide end mill (second roughing pass to get the little details). Nomad #302 60 degree V cutter (finish pass)
magnesium is much more forgiving than aluminum or brass. Speeds and feeds are about two to three times faster than aluminum settings, and step overs were all 50% of the tool diameter.
This project took a total of three and a half hours to complete. it is now producing product on the factory line.
I consider this a very big win for my little Nomad, as well as for myself!!!
People should note that machining magnesium is a little dangerous.
The fine milling swarf can ignite due to heat from rubbing or a spark. If you’ve never seen a magnesium fire, they are pretty impressive. They burn very hot and fast.
Never use water or water based lubricants when cutting magnesium.
If you do have a magnesium fire, never put water on it.
Make sure you have a fire extinguisher nearby when milling magnesium. (Actually you should have one around all the time.)
Yeah, I’ve seen a magnesium fire — set off a thermite device as part of my Air Force training — and have the scar to show for the consequences of it mixing with water — believe me, this is something you want to be very, very, very careful about.
Mg is highly energetic… I’ve made a number of very large composite rocket motor propellant grains using 1000 mesh Mg powder. I cannot echo the water message enough as cited above. It also out-gasses Hydrogen with water in the mix.
EDIT:
Nice work on the die, sir…
I’m curious as to what drove the material choice?
I agree with this post. Magnesium should never be dealt with casually.
I am using a cold air stream to cool the tool, the part, and remove the chips.
High feed rate is suggested, as it gives the tool less time to heat up a spot.
I have two kinds of fire extinguisher with arm’s reach of my machine. one is for normal fires, the other is for fires such as burning magnesium.
Hi there!
Magnesium was chosen for it’s easy machinability, it’s low weight, and the fact that I need to produce these dies as quickly as possible for short-run foil stamping operations.
I should note that I possess a degree in metallurgy and am fully aware of the properties of magnesium, as well as all safety precautions required when machining it.
I’d like to think that Tim’s comment was directed at anyone who might have been reading this and been intrigued by the statement:
magnesium is much more forgiving than aluminum or brass
which, while it’s obvious in retrospect that you mean in machining characteristics, might be seen as something else by someone not familiar w/ the material.
I’ve been tempted by the idea of machining a magnesium archery riser — just not finding any Bear Custom Kodiak T/D A-handles in magnesium (and can’t afford any of the vintage ones I’d want in wood) — really appreciate your sharing your success w/ it — makes it seem a bit more approachable.
Clearly you understand the implications, and this cooling widget looks very intriguing. Thanks for posting this, and please post some stamping results. Again, great work and attention to detail.
