CUTTING SHEET METAL
How to Cut Sheet Metal
Despite what you might think, cutting sheet metal is a lot easier than it sounds. But before you get started there are a few things to consider depending on the type of tool, material and shapes you plan on cutting.
Please note that this is not intended to be a complete guide for how to cut sheet material, instead, it provides general advice for metal cutting and metal cutting tools. You should always follow the appropriate advice provided by the manufacturer of your tool and follow the appropriate safety advice.
Always wear adequate personal protective equipment and take relevant safety precautions when operating power tools, or handling sharp materials. Follow the advice outlined by the manufacturer of your cutting tool.
Always use a cutting lubricant when working with sheet metal, particularly when cutting Aluminium. It is also important to consider that when working with plastic based sheet materials, like plexiglass, rotational cutting tools such as grinders can cause the material to distort or even melt.
Preparing Your Cut
Clean the Material
Before you get started clean the material of any debris that could interfere with the quality of the cut. This will result in a cleaner and more consistent cut, and prevent foreign objects from entering and damaging your cutting tool.
Lubricate the Cutting Path
When cutting sheet metal you should always use a cutting fluid like WD40 or Inox, this is particularly important when working with Aluminium. The use of cutting fluids will improve the lifespan of your cutting blades, prevent damage to your tool and make it easier to cut the material.
Clamp the Material
We recommend that you clamp or fasten your material to a work bench, or hold it in place with a bench-vice. This makes it easier to work with the material as well as preventing it from slipping or moving when you’re cutting. Please keep note that thinner materials may become distorted if they are over-fastened, it is also important to consider that space underneath the material will be required to allow for your cutting tool to operate.
Cutting with Metal Nibblers
Starting Your Cut
Always power on your unit before making contact with the material. With the tool running, slowly advance the cutting head through the material in a consistent fluid motion. Keep in mind that you should always cut on the outside of your intended path to allow for the width of the cutting blade (kerf).
It is possible to cut from the inside of the material (in the case of a circle) by drilling a hole with a sheet metal drill bit large enough to facilitate the width of the cutting die. To find out more about cutting circle, click ‘here’.
Using mounting clamps is a great way to use nibblers, freeing up both hands to manoeuvre the material. This makes it easier to cut large pieces of material as well as making more precise cuts.
If or should you decide to bench mount your tool, make sure that your drill and nibbler are secured firmly as the torque from cutting (especially when working with thicker materials) can cause them to rotate in the clamp housing, requiring you to stop working to re-position them.
Manoeuvring Your Tool
Nibblers are arguably the easiest tool on the market to manoeuvre, making them an ideal choice for cutting complex shapes, curves and straight lines on flat or complicated profiles. Nibblers like our Professional Nibbler have a 360° cutting range, and a minimum turning radius of 5/16 inch (8 mm) meaning you can change direction rapidly by simply moving your tool as it advances through the material, using one hand to push and the other to manoeuvre it.
Cutting with Clamps
Similarly making sure your tool is operating before making contact with the material, with two hands advance the material into the cutting punch to begin your cut. Simply manoeuvre the material to change the direction of the cut, and quickly turn the material to achieve tight curves and bends.
Nibblers produce waste in the form of small ‘chips’, we recommend placing a bucket or box under what you’re cutting to catch them for easy disposal. They can be sharp so always handle them with precaution.
Cutting Metal with Tin Snips
Choose the Right Snips
Before you get started make sure you’ve got the right tin-snips for the job. Tin-snips come in straight, left and right cutting variants indicated by their colour (red = left, yellow = straight, green = right). Tin-snips also come in two main ‘patterns’, straight and duckbilled. Straight (including left and right) are designed for slight curves, whereas duckbilled patterns are better suited to creating curves and circular shapes.
Beginning to Cut
With the material cleaned lubricated and clamped in place, align the tin snips where you want to begin cutting and touch the upper blade of the tool against the sheet material, begin to squeeze the handles together to make the first cut, check the cut is even before continuing.
If you need to change direction simply alternate between the tin-snip suited to that change, for example if you were cutting a straight line that turns into a rightward bend, simply change between a straight and right cutting pair of tin-snips.
Cleaning up Edges
In most cases, tin-snips can leave sharp distorted edges that require cleaning up. Using a metal file and great caution, tidy up these edges to as so they’re no longer a hazard to touch.
Cutting Metal with Power Shears
Consider the Kerf
Depending if you’ve got a double cutting model, it is important to consider the width of the kerf before you begin cutting. If the cutting blades are centred on the planned line of cut, the final piece being cut will be undersized. As such it is important to make accommodations for this by cutting off centre, so that you’re only cutting into the waste material.
Beginning Your Cut
Align the cutting blade with the material and touch the upper blade of the tool against the material and slowly begin to cut by moving the tool forward. The waste material will naturally ‘curl’ into a cylinder and extrude out to the right of the tool.
Continue the cut in a singular fluid motion, this will ensure that the cut is even. Tight curves may push the tool beyond its limits and create sharp or jagged edges. As such we recommend sticking to straight lines, or making multiple wide-cuts to achieve tighter curves.
For the most part, power shears won’t create sharp edges unless you push them beyond their limits (wide curves), or don’t create a smooth cut. If you are left with sharp edges, you should always file them down as so they’re no longer a hazard to touch. When disposing of the spiraled cutting waste, use caution as it may be sharp.
Cutting Metal with an Angle Grinder
Choosing the Right Disk
When it comes to cutting, the grain and quality of the cutting wheel is important, with disks containing aluminium oxide offering a faster, smoother and easier to control cut. It is important to consider that INOX grade wheels do not contain iron which means they have the ability to cut both stainless steel and mild steel. If a disk does not specify use on stainless steel, then it is most likely only suitable for mild steel cutting. As stainless steel is one of the harder types of material to cut, a wheel that will cut stainless steel will most likely cut all materials including aluminium.
Disk thickness is also a major consideration when purchasing a cutting disk, with standard everyday jobs on material like mild or stainless steel benefitting from a 0.04-0.06” Inch (1-1.6mm) disk. Alternatively, when cutting thin sheet metal a (1-0.8mm) disk will cut the material faster minimising discolouration and reducing the amount of clean-up work.
The rule of thumb is the thicker the material, the thicker the disk you should get, however keep in mind that the thicker the wheel the slower the cut will be, as well as generating more friction and heat, often discolouring the material. Finally when cutting Aluminium it is recommended to apply cutting lubricant to prevent the disk from chipping.
Always make sure your grinder is turned off and unplugged from the wall when installing your cut-off disks and follow the instructions provided by the manufacturer of the tool and cut-off wheel, and ensure the RPM of the disk matches or does not exceed the rated speed of your tool.
Beginning Your Cut
Power on the grinder before making contact with the material, if the cutting wheel makes contact with the material before it is powered on, the sudden torque will cause the tool to skip across the surface of the material potentially causing injury. It is also important to keep the tool vertical to the work surface, where changing angle may cause the disk to break and shatter mid-cut.
Slowly progress the cutting wheel down and through the material letting the speed of the wheel do the work, don’t press down too hard on the work surface. Once the cutting wheel has cut down and through the material, you can begin to progress the tool along your desired cutting path making sure to cut with the edge of the wheel. Do not attempt to change cutting direction while the tool is in the material, remove the tool then come back down through the material to change direction.
In most cases grinders will leave sharp, or hazardous edges to the touch. Using a metal file, remove these edges as so they’re no longer dangerous to touch or handle.
Cutting Metal with a Plasma Cutter
Getting Set Up
Turn on your air compressor (if applicable) and begin to build air pressure, open any doors or windows to help ventilate the area. Next clear your surrounding area of any hazardous objects such as flammable liquids or materials and clean the cutting area with a wire wheel or grinder down to the bare metal.
Make sure that when you begin cutting, you or your plasma cord won’t get hit by any falling metal when it drops.
Connect the ground clamp of the plasma cutter to the piece of metal that will stay stationary when the metal is cut. Put on your safety equipment and plug your plasma cutter into your air hose and double check that your machine is receiving both air and power.
Beginning to Cut
Line yourself up with the piece of material so that you will be at the furthest possible position from any sparks. Make sure you are safe from any falling material and have a clear view of your cut.
With your safety gear on, position your torch slightly over the material to prevent blowback.
Powering on the torch, begin a slow smooth motion cutting into the material. Continue to cut until your material is cut through and hits the floor. Let the material cool before you handle it, larger pieces of material will be cooler than smaller pieces!
Once you’ve finished cutting and waited for the material to cool down, tidy up the edges with a metal file or grinder. When working with thicker materials, we recommend using a grinder to speed up this process.