Can Sparks From Cutting Metal Start A Fire?

If you are a professional welder or a metal-working hobbyist, you have likely seen sparks fly, literally.

Anytime small fragments of metal are broken off from the surface, they heat up and ignite due to friction.

The sparks that result are the little pieces of metal burning when they encounter oxygen in the air. 

So you might be wondering…

Can sparks from cutting metal start a fire?

The sparks that result from cutting or grinding metal can be dangerous. 

Not only can they burn the eyes and/or the skin, but they can also ignite combustible or flammable materials in the area, causing a fire. So yes, sparks from cutting metal can start a fire.

Therefore, it is imperative that you always take the proper precautions when welding or doing any kind of metalwork.

Welding

Most welding fires are caused by sparks or when droplets of melted metal land on flammable materials.

As well, when combustible gasses or vapors in the air are ignited through heat, this too can cause a fire.

Molten metal sparks, for example, are caused by the heating process of iron or steel typically referred to as arc welding.

Arc welding is a process by which pieces of metal are joined using electricity. The applied electrical current produces sufficient heat to melt the metal.

When the melted metals cool, the pieces bind themselves together at the melting point.

This process often creates a ‘spray of sparks’ that can be dangerous and cause a fire should they land on anything flammable, such as wood, paper, or fabric.

Cutting Metal Without Sparks

The best way to cut iron or steel without sparks is to use a hacksaw rather than an angle grinder.

Attaching a carbide grinding bit to a rotary tool such as a Dremel, for example, limits the amount of sparking and helps remove any small pieces of metal your grinder may miss or cannot reach.

If you want no sparks at all, then consider cutting a different type of metal such as aluminum.

Another option is to put duct tape on the iron or steel. This works to reduce the amount of friction caused by using an abrasive tool on a metal surface.

Less friction means less sparks. Simply wrap some duct tape around the metal two or three times to create a padded surface.

Using a pencil, draw a ‘cut line’ on the tape, to ensure the proper length, and then cut. It is that easy!

Angle Grinder

Cutting metal with an angle grinder causes a lot of sparks. However, the sparks that result are not that serious of a fire hazard.

The reason being that the sparks emitted, generally, do not get hot enough to ignite. Therefore, the chances of an accidental fire occurring are quite low.

The only way a fire could start is if the sparks happen to fall continuously on the same spot of highly flammable material.

Metal Sparks from Angle Grinder

While metal sparks have the potential of reaching 2,000 degrees Fahrenheit (or 1100 degrees Celsius), those produced when using an angle grinder have a small mass, not enough to cause a fire, in most cases.

That does not mean, however, that is not possible. Proper safety measures should always be taken when using a power tool to cut or grind metal.

Aluminum

Anytime metal is struck or cut, it will spark because of friction. Aluminum does not spark near as much as iron or steel, however.

It is a softer, lighter metal which produces less heat and friction when cut. As a result, it sparks less and therefore is less likely to start a fire.

Metal that makes most sparks

The two types of metal that spark the most are iron and titanium. The surface area of iron is larger than its volume and as a result will heat up very quickly and spark easily.

These sparks glow bright red and can start a fire if they land on any flammable material.

Titanium, on the other hand, is a non-ferrous metal and gives off a ‘shower of sparks’ when cut. These sparks are very tiny and burn white-hot.

They can ‘fly’ about easily and ignite on any nearby combustible material, thus causing a fire.

Safety Precautions When Cutting Metal

Anytime you work with metal, the most important thing is to do is try and avoid injury.

When cutting or grinding metal (or any job requiring you to use a power tool and/or heat up metal), be sure to follow these important safety measures:

  • begin by inspecting all tools carefully to ensure they are in good condition
  • always wear safety gloves, especially if you are a beginner
  • always wear safety glasses or goggles, preferable ones that are CSA-certified with side shields
  • always wear earplugs when working with loud power tools, such as an angle grinder
  • be sure to use a well-mounted vice to hold your metal pieces securely while working on them
  • never grasp hot metal tightly – instead, use a light grip to prevent nicks and cuts
  • never, ever run your bare fingers across the raw edge of the metal
  • anytime you use a tin snip, be sure to keep it moving deep along the cut line – avoid making short cuts with the edges of the tool as this will create jagged edges
  • do not sweep scrap pieces of metal into the trash with your hands – use a brush or vacuum instead and be sure to wait until the pieces have cooled completely before discarding
  • always work in a well-ventilated area with adequate lighting
  • make sure the work area is free of combustible materials
  • if possible, invest in good-quality tools and never use tools that are damaged

Should the unthinkable happen and a metal fire breaks out in your workshop, never try to put it out using a CO2 fire extinguisher or water. Pouring water over a metal fire causes the heated particles to separate into hydrogen and hydroxide.

Hydrogen acts as an accelerant by increasing the rate of combustion which can cause an explosion. The correct way to put it out is to use a powder extinguisher instead.

Angle Grinder Sparking Frequently Asked Questions

Why is my angle grinder sparking?

Grinding equipment is always going to produce a lot of friction because the pressure has to be incredibly high to grind the thick materials a grinding tool is used on. Steel and any type of metal will produce sparks during the grinding process and your grind tool is designed to cause so much friction that sparks have no way to not be produced during the process.

The entire sparking process is related to oxidation coming into contact with the friction produced from the movement of the grinder. This is not a malfunction with the equipment and is completely normal.

Sparks are not anything to become concerned about when using an angle grinder, in fact, sparks are completely normal and will emit from virtually any material that the grinder comes into contact with. The sparks are simply the release of heat and pressure.

Are angle grinder sparks dangerous?

The sparks emitted from angle grinders are not completely dangerous at a surface level. The particles emitted from the materials are very small, and as soon as the spark flies off the wheel, the sparks have cooled to a significant degree.

So, if the sparks land on your skin or even your clothing, you may not even feel the burn of the sparks since the particles have had time to cool.

The sparks aren’t a serious fire hazard because they aren’t that hot, therefore accidental fire won’t occur unless the grinding sparks fall continuously at one spot on a flammable material.

But it’s also better to be safe than sorry, so make sure that there isn’t any flammable material near you when using the angle grinder.

How hot are metal sparks from a grinder?

Angle grinder metal sparks are incredibly hot; some sparks have the potential to reach temperatures of around 2,000 degrees Fahrenheit (1100 degrees Celsius).

When steel is ground against with as much pressure used by a grinder, the sparks emitted from the grinder have a very low mass, therefore, the heat of the sparks dissipates quickly once the sparks bounce off of the grinder.

The sparks are very hot but the heat quickly fades because the mass is not large enough to sustain such incredible temperatures for a long period of time.

For a metal such as titanium (more on this below), the sparks can be much hotter but also not an overall cause for concern due to low mass output.

Conclusion

The sparks that result from cutting or grinding metal can be dangerous.

Not only can they burn the eyes and skin, but they can also ignite flammable materials such as wood, paper, or fabric causing a fire.

Therefore, it is imperative that you always take the proper safety precautions when cutting or welding metal.

In an event that a metal fire breaks out in your workshop, never try to put it out using a CO2 fire extinguisher or water.

Pouring water over a metal fire causes the heated particles to separate into hydrogen and hydroxide.

 The correct way to put it out is to use a powder extinguisher instead.

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