MG · 10 grades
Magnesium Alloys
The lightest structural metal we machine - and the one with the strictest rules.
Magnesium is roughly 35% lighter than aluminium for similar stiffness, which is why it shows up in aerospace housings, racing components and portable equipment. It also behaves differently from anything else in the shop: fine chips will ignite, water-based coolant is not used on the swarf, and the fire risk changes the housekeeping rules for the whole cell. Handled properly it machines faster than aluminium and leaves an excellent finish.
What this family does well, and where it bites
- Density 1.74 g/cm³ - about 65% of aluminium, 22% of steel
- High cutting speeds, sharp positive tooling, and chips kept moving out of the cut
- Dry machining or mineral-oil mist only, with dedicated chip handling
- Corrosion protection is mandatory: chromate conversion or anodising, plus coated hardware
Magnesium Alloys grades we machine
Each grade page carries the properties as supplied, what heat treatment does or does not do to it, the achievable surface finish, starting cutting parameters and the DFM notes that matter for that specific grade.
AZ31B
9/1050–60 HB · 260 MPa
Magnesium machines faster than aluminium with a sharper finish, provided the chip is kept moving and the swarf rules are respected.
AZ91D
8/1065–75 HB · 230–250 MPa
The most common die-casting magnesium: high aluminium content gives good castability and decent strength, and it machines fast with excellent finishes.
AZ80A
8/1070 HB · 380 MPa
A wrought magnesium alloy with the highest strength of the common AZ grades: it machines like a harder aluminium and holds a better finished surface than the casting grades.
ZK60A
7/1070 HB · 340–360 MPa
A zirconium-containing magnesium alloy with the highest strength of the conventional grades.
AM60B
8/1060–65 HB · 220–240 MPa
The ductile die-casting magnesium: less aluminium than AZ91, so lower strength but far better elongation.
AZ91E
8/1065–75 HB · 165–275 MPa
The sand-casting version of AZ91 with a high-purity specification: lower strength than the die-cast grade but a far lower casting cost for low volumes, and it machines the same way.
AM50A
8/1055–65 HB · 200–220 MPa
The most ductile of the common die-casting magnesium grades: lower strength than AM60, higher elongation, and it machines like the rest of the family.
AZ61A
8/1060 HB · 260–300 MPa
A wrought magnesium alloy sitting between AZ31 and AZ80: more strength than AZ31, easier to extrude and form than AZ80, and it machines cleanly.
Elektron 21
6/1075–85 HB · 280–300 MPa
A rare-earth magnesium alloy for high-temperature service: around 200 °C where the conventional AZ and AM grades have long since crept.
WE43
6/1075–90 HB · 250–280 MPa (T6)
A yttrium rare-earth magnesium for high-temperature service: it holds its strength to around 250 °C where the AZ and AM grades have long since crept.
Questions buyers ask
- Can you actually machine magnesium safely?
- Yes, with the right controls. Fine magnesium chips can ignite, so the rules are: no water-based coolant on the swarf, no accumulation of fine chips, dedicated tooling that stays sharp, and a class D extinguishing agent within reach. We run magnesium in a controlled cell and handle the chips the same day they are produced.
- Why is magnesium not used more widely if it is the lightest?
- Corrosion. Bare magnesium reacts with moisture and needs a coating system that is maintained for the life of the part, and galvanic contact with steel or stainless fasteners has to be broken with isolation. That is a design burden most projects avoid by using aluminium instead.