A Guide to Magnesium CNC Machining

Key Takeaways

• Magnesium alloys are the lightest practical metals, with excellent specific strength.

• They provide dent resistance and vibration damping, making them valuable in electronics and automotive applications.

• Machining requires strict fire prevention due to the risk of violent burning.

Overview

Magnesium alloys are the lightest practical metals and have the highest specific strength among alloys. Magnesium is also abundant and readily available, which makes it a valued material in many fields.

In recent years, magnesium alloys have gained significant interest for their potential in labor-saving and weight reduction applications. However, machining magnesium alloys comes with risks such as fire, limiting the number of processors able to handle it safely.

Characteristics of Magnesium Alloys

The "Lightest" Practical Metal with High Strength-to-Weight  Ratio

Magnesium is the lightest among practical metals and the sixth most abundant metal on Earth, making its use potential the highest of all metals. Magnesium has a specific gravity of 1.74 g/cm³, and below is how it compares to other metals:

• About 2/5 that of titanium (4.51 g/cm³)

• About 1/4 that of iron (7.87 g/cm³)

• About 2/3 that of aluminum (2.70 g/cm³)

Its specific stiffness and strength exceed those of aluminum alloys and iron, making it a strong yet lightweight material. This weight reduction improves usability, safety, and energy efficiency across industries that previously relied on heavier metals like iron.

Excellent Dent Resistance

Magnesium alloys have a high work-hardening rate, meaning they become harder when deformed under force. Compared to aluminum alloys, dents from impact are smaller, which makes magnesium alloys suitable for small electronic devices such as digital cameras and mobile phones.

Excellent Vibration Damping

Magnesium alloys offer the highest vibration damping ability among practical metals. This property improves with higher purity magnesium. Applications include:

• Hard disk drives, CDs, and MDs to reduce vibration impact

• Car wheels and steering wheels for smoother operation

Stable Electromagnetic Shielding

Magnesium alloys exhibit a stable shielding effect of 90-110 dB in the 30-200 MHz range, reducing risks of machine malfunction or health concerns from prolonged electromagnetic exposure. Electromagnetic waves include radio waves, magnetic fields, light, and radiation. Electromagnetic shielding helps prevent machine malfunctions and potential health issues that can result from prolonged exposure.

Excellent Dimensional Stability

Magnesium alloys are easy to heat and cool due to their low specific heat (the amount of heat required to raise the temperature of 1 gram of a substance by 1 Kelvin). They also maintain dimensional stability, changing only 6 × 10⁻⁶ after heating at 150°C (302°F) for 100 hours. Furthermore, there is virtually no change below 100°C (212°F).

Excellent Machinability

Magnesium has low cutting resistance and is an easy metal to machine. This shortens the machining time and extends tool life. Below is a comparison of cutting power index (the lower the number, the easier the material is to cut):

• Magnesium alloy: 1.0

• Aluminum alloy: 1.8

• Copper: 6.3

Recyclable

Magnesium alloys are also used in die-cast products, which naturally produce defects and cutting chips. This makes recycling scrap generated during processing indispensable. Like aluminum alloys, magnesium alloys require only 4% of the energy compared to new ingot production.

Burns Violently

Magnesium ignites easily and burns intensely. If hot magnesium contacts water, it can generate flammable gases, making conventional fire suppression difficult. Strict fire prevention measures are critical, including:

• Avoiding contact with flames, high-temperature objects, or water

• Frequent ventilation

• Prompt removal of machining chips

Actual fire accidents have occurred in processing sites, so extreme caution is required during handling. Because of this, magnesium is classified as a difficult-to-machine material.

Applications of Magnesium

Magnesium is often used as an additive in aluminum alloys, accounting for about 40% of total demand. When used directly, it is usually alloyed with aluminum or zinc.

Applications include:

• Automotive parts: steering wheels and engine blocks

• Electronic components: aircraft, laptops, mobile phones, and DSLR cameras

• Welfare/medical products: canes and wheelchairs.

In most cases, the objective is weight reduction.

Magnesium CNC Machining at Yumoto Electric

Yumoto Electric delivers high-quality components fast, worldwide. We provide precision machining for a wide range of metals using milling, turning, and specialized metal processing. We have experience with over 200 materials including aluminum alloys, stainless steel, molybdenum, and titanium. 

If you’re unsure about material selection or machining methods, we offer complimentary consultations to help optimize your design and production. For any questions, please feel free to contact us.