In the process of machining magnesium alloys, the chips and fine powders produced have the risk of combustion or explosion.

In the process of magnesium alloy processing, the influencing factors of chip temperature rise to flash point or combustion are as follows:

A. The relationship between machining speed and cutting rate. The generation of cutting heat increases in proportion to the cutting speed. The higher the relative temperature, the greater the possibility of ignition.

B. Other factors. Feed rate or cutting volume is too small; The pause time in the process of processing is too long; The back Angle and chip space of the tool are too small; High cutting speed without the use of cutting fluid; Spark may be generated when the cutting tool collides with the dissimilar metal core lining embedded in the casting. Magnesium chips accumulate around or under the machine tool.

Safe operating procedures for machining

a, cutting tools to keep sharp, and grind out a large rear Angle and clearance Angle; Dull, sticky, or cracked tools are not allowed.

b, under normal circumstances, try to use large feed for processing, avoid using small feed, in order to produce large thickness of chips.

c, do not let the tool stop on the workpiece.

d. Use mineral oil coolant to reduce cooling when using small cutting amount.

e. If there is steel core lining in the magnesium alloy parts, the spark should be avoided from the collision with the tool.

f. Keep the environment tidy and clean.

g. Smoking, fire making, electric welding and other inflammable operations are strictly prohibited in the processing working area.

3. Safety problems in grinding

Magnesium powder burns easily and can cause an explosion when suspended in air.

Therefore, the following preventive measures must be taken when grinding magnesium alloy parts:

a. There must be a grinder specially used for processing magnesium alloy parts. The vacuum cleaner should be cleaned thoroughly before dressing the grinding wheel.

b. When regrinding the surface of magnesium alloy parts that have been washed with chromate, sparks may be caused. Therefore, special care should be taken to avoid dust accumulation nearby.

c. Grinding equipment operators shall use smooth caps, smooth gloves and smooth flame-retardant suits without pockets and cuffs. Aprons or protective suits shall be clean and dust-free and easy to remove.

d. The storage of magnesium waste chips should be cleaned in time, and the storage time should be set to Z long.

e. Sufficient yellow sand shall be stored in the working area to prevent fire fighting.

4. Treatment of magnesium chips and fine powders

The waste must be kept apart from the rain

The waste magnesium chips produced by processing are packed in barrels and soaked with magnesium processing special cutting fluid. Place it in a place that is ventilated but not exposed to rain and water, and do not cover it to allow the hydrogen gas that may be produced to evaporate naturally (if the hydrogen is not fully volatilized, it may cause explosion).

Smoking, welding and other inflammable activities are strictly prohibited.

5. Fire extinguishing by burning magnesium chips

Class a and D fire extinguisher.

The material is usually a sodium chloride-based powder or a graphite-based powder that has been passivated and works by smother the fire by removing oxygen.

b. Covering agent or dry sand.

It can be used to cover small fires, and the principle is also to extinguish fires by removing oxygen.

c. Cast iron debris.

It can also be used in the absence of other good fire extinguishing materials, and its main function is to reduce the temperature below the ignition point of magnesium, rather than to smother the fire.

In short, under no circumstances should you use water or any other standard fire extinguisher to put out a fire caused by magnesium. Water, other liquids, carbon dioxide, foam, etc. all react with the burning magnesium and intensify the fire rather than suppress it.

The above content is for reference only, if you have different opinions, welcome to correct!