Can an oscillating tool cut hardened steel?

An oscillating tool, also known as a multi-tool, is a versatile power tool that can be used for cutting, sanding, grinding, scraping and more. Oscillating tools have a rapid side-to-side oscillating motion that allows accessories and blades to move back and forth very quickly. This oscillation allows the tool to cut into materials like wood, plastic, and soft metals with ease. But can an oscillating tool successfully cut through hardened steel?

What is an oscillating tool?

An oscillating tool, sometimes referred to as a multi-tool, is a handheld power tool that features a flat blade that rapidly moves back and forth in an oscillating motion. This rapid oscillation allows the blade to move very quickly, which gives it the ability to cut through various materials. Here are some key features of oscillating tools:

• Powerful motor – Generates the rapid oscillating motion. Motors range from about 85 to 230 watts.
• Variable speed settings – Speed can be adjusted for optimal performance in different materials. Speed range is typically anywhere from 10,000 to 22,000 oscillations per minute.
• Interchangeable blades and accessories – Different blades and attachments can be switched out for specific jobs like cutting, sanding, scraping, grinding, and more.
• Compact size – Typically about 5 to 10 inches long and weighing 2 to 5 pounds. The small size allows for use in tight spaces.
• Cordless or corded – Most models are either cordless (rechargeable battery-powered) or corded (plug into outlet).

Oscillating tools are valued for their versatility – the ability to perform many different tasks with the interchangeable blades. Common uses include:

• Cutting openings or holes in drywall
• Cutting wood, plastic, or soft metals
• Sanding joints, edges, and hard-to-reach areas
• Scraping away old caulk, glue, paint, etc
• Grinding and polishing in tight spaces
• Detail trimming and finishing work

What is hardened steel?

Hardened steel refers to steel that has been strengthened through heat treatment processes that increase hardness and durability. Here are some key things to know about hardened steel:

• Increased hardness – The heat treating process modifies the internal structure of the steel, increasing hardness and wear resistance.
• Higher carbon content – Steels used for hardening usually have a higher carbon content, typically 0.3-0.6% carbon.
• Quenching – The steel is heated up to a high temperature then quickly cooled (quenched) to lock the hardness.
• Tempering – A secondary low temperature heating may be done (tempering) to reduce brittleness.
• Strength and durability – Hardened steel has higher strength, hardness, and wear resistance compared to untreated mild steel.
• Common applications – Cutting tools, bearings, automotive parts, knives, industrial components.

The hardness of steel is usually measured on the Rockwell C scale (HRC). Hardened steel typically has a hardness of HRC 45 or greater, compared to mild steel which may have a hardness of around HRC 15-20.

Can an Oscillating Tool Cut Hardened Steel?

Oscillating tools are designed to make quick cuts in wood, drywall, plastic and thin sheets of soft metals like aluminum. But hardened steel presents some challenges:

• Hardness – The hardened steel has a higher hardness and strength that makes cutting more difficult.
• Slow cutting – The oscillations may not be fast enough to cut efficiently through the tough hardened steel.
• Blade wear – The rapid wear and tear on oscillating blades increases when attempting to cut hardened materials.
• Overheating – Friction generated from cutting hardened steel can cause the blade to overheat.
• Tool strain – Attempting to cut hardened steel can overwork the tool’s motor and gears.

For these reasons, standard oscillating tools and blades are generally not well suited to cutting hardened steel. The hardness offers too much resistance and can damage blades and overload the tool. There are a few possibilities though where an oscillating tool may be able to cut hardened steel:

Specialized Oscillating Tool Blades

Some oscillating tool makers offer specialty blades made from harder, more heat-resistant materials that can handle tougher jobs. These include:

• Bi-metal blades – Made from a steel core bonded to a hardened cutting edge for durability.
• Carbide grit blades – carbide particles fused to cutting edges provide hardness for metal-cutting.
• Diamond grit blades – Tiny diamond particles bonded to the blade for abrasive cutting of hard materials.

These types of hardened, abrasive grit and diamond blades can cut thicker and harder steels. But they still have limits and cutting very thick, hardened steel will wear them down quickly. These specialty blades are also more expensive than standard oscillating blades.

Cutting Thinner Hardened Steel

For thinner hardened steel sheets, an oscillating tool with a quality carbide or diamond grit blade may be able to make the cut. The key factors are:

• Steel hardness – The lower the HRC, the better the chances of cutting it.
• Steel thickness – Thinner material improves chances of cutting through.
• New, sharp blade – A fresh, quality grit or diamond blade is crucial.
• Slow feed rate – Cut very slowly to minimize heat and wear.
• Lubrication – Use a lubricant to keep blade cool.

With ideal conditions, an oscillating tool may be able to cut through thinner hardened steel up to about 1/16 inch thickness. But the cutting depth and feed rate will be very slow and the blade life very short. The tool’s chances diminish as the steel gets thicker and harder.

Alternative Methods for Cutting Hardened Steel

For most situations requiring cuts in hardened steel, an oscillating tool is not the best choice. Here are some other cutting tools better suited for hardened steel:

Abrasive Cutoff Saw

A abrasive cutoff saw uses an abrasive disc similar to a grinder to cut through steel and other hard materials. Models using thin abrasive discs specifically designed for cutting metal can slice through hardened steel much faster than an oscillating tool. Cutoff saws are available in both portable and stationary benchtop styles.

Chop Saw

A chop saw is a power saw with a pivoting arm holding an abrasive or carbide-tipped cutting disc. It can cut through hardened steel much faster than an oscillating tool. A chop saw makes quick straight cuts through steel bar, rod, and tubing.

Circular Saw with Abrasive Blade

A handheld circular saw outfitted with a reinforced abrasive or diamond grit metal cutting blade is able to cut hardened steel sheets and plates. It cuts faster than an oscillating tool and allows straight or curved cuts.

Plasma Cutter

A plasma cutter uses a focused plasma arc alongside compressed air to cut cleanly through all types of steel, including hardened steel. The extremely high heat of the plasma jet melts and blows away the steel smoothly and quickly.

Angle Grinder

A handheld angle grinder with a thin cut-off disc can cut hardened steel. It takes patience to cut all the way through thick steel but an angle grinder can make the cut. Lubrication and pausing to allow the metal to cool helps.

Conclusion

In summary, while specialized blades exist that may be able to cut thinner hardened steels under ideal conditions, standard oscillating tools are generally not suitable for cutting hardened steel in most real world circumstances. The hardness and strength of hardened steel exceeds what oscillating tools are designed to handle. For intensive cutting jobs on hardened steel bar, rod, tubing, plate and sheet, use an abrasive saw, chop saw, circular saw, plasma cutter, or angle grinder to achieve faster, deeper cuts without ruining blades or overworking the tool.