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+--- Thread: How To Cut Aluminum Sheet Metal (/Thread-How-To-Cut-Aluminum-Sheet-Metal)
How To Cut Aluminum Sheet Metal - aluminiumsheet - 01-19-2020
Aluminum sheet metal can be cut with a variety of methods ranging from manual tools to highly advanced industrial systems. In this posting we will take a look at some of the most common types of cutting aluminum. When determining which method of sheet metal cutting is right for you you should take into consideration the factors of flexibility, speed, accuracy, finish, cost and automation. There are a few basic properties of aluminum that affect how it can be cut. One factor which helps aluminum is that it is a relatively soft metal. This means that chisels, snips, hacksaws and hand shears are effective on the thinner gauges. If your working from a garage or custom job shop a few inexpensive tools can get you well on your way.
Hand Tools
Cost : $20 – $100
Flexibility : Low
Speed : Very Slow
Accuracy : Very Low
Finish : Poor
Automation : None
Chisel and Hammer
Cutting aluminum sheet metal with a hammer and chisel is relatively straight forward, line up the edge of the chisel along the line you wish to cut and strike the chisel with a hammer. Using a softer piece of material such as wood as a backer will allow the chisel to push through the metal and prevent wear on the chisel’s tip. You will have to continue your way down the cut line cutting the metal like a can opener. This process of cutting aluminum is very slow and labor intensive. It may be appropriate if you’re working on a small project in your garage. The edge quality of this method is going to be very poor and you’ll probably need to take a file to the edge of the metal to make it safe for handling.
Snips
Tin snips, also known as aviation snips are basically highly leveraged and rugged scissors which can be used for cutting through aluminum. You will be limited to the gauge of aluminum which you can cut, anything above 18 gauge is going to be a challenge. For a reference on gauge thickness see our gauge chart. these snips come 3 basic varieties allowing for straight, left hand curved and right hand curved cuts. For most applications it is necessary to file and clean up the edges left by a snip. When cutting with tin snips it’s advised that you keep the top blade seated on the metal and pull the bottom blade up into the top blade.
Hacksaw
A hacksaw can be particularly effective for cutting small lengths of sheet metal but lends its self to cutting tubing and bar stock because the hacksaw will have a limited throat depth, meaning it can cut very far into the metal. Cutting aluminum with a hack saw will wear the blades down relatively fast compared to wood, but not nearly as fast as steel or stainless steel will.
Hand Shear
Disk blade shears are a tool which is basically a specialized can opener which features a round cutting blade and snip. Good for tight corners and leaves a nice edge compared to other hand tools, though it still may require cleaning.
Bench Tools
Cost : $100 – $1000
Flexibility : Medium – Low
Speed : Slow
Accuracy : Low
Finish : Poor
Automation : None
Straight Bench Shears
Bench mounted shears are able to cut through relatively thick sheets of aluminum though their design will tend to limit your cuts to straight lines. These types of shears lend themselves towards hobbyists and sheet metal shops doing custom or repair work. Most machines are built well and will last a lifetime if the blades are kept clean and sharp.
Beverly Throatless Shears
A common throatless shear known for one of its major manufacturers, Beverly, are common to small sheet metal shops because of their versatility and reliability. By properly spacing the cutting edge from the back plate you can achieve a nicely rounded edge which may not require additional cleaning. These shears come in three sizes, B1, B2 and B3 depending on the size and power required.
Band Saw
A carbide tipped or even standard steel blade will typically suffice for most gauges aluminum up to 1/4” thick, though you’ll have to move relatively slowly on the heavier stuff. Putting a piece of particle board or plywood under the sheet metal is said to help with the process. This may help to pull heat away from the aluminum which has the tendency to absorb the heat. In addition to this masking tape on top of the metal will also help. There ware various waxes and cutting oils which help keep the metal cool and allow the teeth to cut smoothly.
Stationary Nibbler
A single tool Punch Press which is set up to perform a nibbling operation, these tools can cut any profile within its throat however they require a wide kerf and leave a serrated edge. While cutting the aluminum it’s important to remain conscious of the eject chips from these machines, they can easily accumulate and cause a safety hazard..
Power Tools
Cost : $75 – $300
Flexibility : Medium
Speed : Medium
Accuracy : Low
Finish : Mixed
Automation : None
Angle Grinders
Cutting aluminum with any sort of grinding device is particularly challenging. Because the metal is able to absorb the heat energy and has a low melting point it can melt and re-solidify around the blade during operation causing it to bind up dangerously. Cut with the intention of removing the metal, not griding it away.
Power Shears
Hand held micro shears are very effective for cutting aluminum sheet metal because they can be directed across the sheet with relative ease. They do not generate any where near the heat of an angle grinder so melting of the metal is not a general concern. Noise, sheet vibration and the finish edge quality are common draw backs of power shears. Unless you are able to stabilize the work piece with clamps you should be familiar with how the tool is going to move itself and the sheet.
Electric Jigsaw
Handheld jigsaws provide a very mixed bag when it comes to cutting aluminum, with the right tool and the right bit or blade you can easily cut through thick sheets and other forms of stock. However with the wrong saw and wrong blade you will find yourself damaging both the workpiece and the tool.
Nibbler
Portable nibblers exhibit the same pros and cons as their bench top models. The softness of aluminum makes them viable for most light gauges.
Heat Cutting
Cost : $200 – $900
Flexibility : Medium
Speed : Medium – High
Accuracy : Low
Finish : Poor
Automation : None
Oxygen-Hydrogen Torch
Oxy-hydrogen torches are superior to acetylene version because of its clean flame. The heat from the torch combined with a steady stream of oxygen rapidly oxidizes the sheet metal and blows the weakened metal away. Cutting with an Oxy-hydrogen torch creates a lot of heat and sparks but can cut thick sheets of aluminum and move at a relatively high speed. The torch doesn’t need any sort of backing and is portable, which makes it ideal for working in difficult to reach spaces.
Plasma Torch
The plasma torch works similarly to an oxy-hydrogen torch however instead of oxidizing the metal the plasma ionizes it with a strong electro magnetic field. The speed of which you cut the aluminum will determine your edge quality, aluminum should be cut at a higher speed compared to steel. In addition to the heat from the torch this weakens the sheet metal under the torch and allows it to be blown away with high pressure air. The plasma torch is very versatile when it comes to the type of material it can cut and, like the oxy-hydrogen torch, it is easily maneuverable along a sheet and in tight places. This makes it a common choice for custom sheet metal shops.
Industrial Cutting
Cost : $10,000 – 5,000,000+
Flexibility : Very High
Speed : Very High
Accuracy : Very High
Finish : Excellent
Automation : Many Options
Plasma : A CNC controlled plasma bed is basically the cheapest form of industrial cutting available. Cutting speeds for aluminum are going to be different than those of steel. The faster you cut aluminum the cleaner the edge will be.
Water Jet
Probably the preferred method for cutting intricate or thick aluminum the water jet focus a very thin stream of water mixed with abrasives at extraordinary pressures and very high speed into the sheet metal. This jet of water eats away at the metal and leaving a clean smooth edge. Heat dissipation is not a concern with aluminum because unlike the laser systems the water jet is not melting the metal, meaning there isn’t a significant difference in the energy required to cut steel or aluminum. Water jets are surprisingly capable of cutting very thick sheet metal, up to a few inches thick with very high accuracy. Their main advantages are the finished edges, variety of materials and accuracy.
Punch Press
Punch presses use shaped tools to knock out geometry in sheet metal. Larger presses can be loaded with dozens of different types of tools for special cutting and forming. They are not typically as quick as lasers but they offer the ability to stamp, roll and form the metal while cutting. This allows for the formation of louvers, jogs,beads, and impressions which lasers cannot form. They are also typically cheaper on the front end when compared to lasers however there are maintenance costs associated with the tooling.
Lasers
Modern lasers will be effective on cutting light to medium gauges of aluminum. Because aluminum is able to more readily absorb heat compared to steel an industrial laser will require a large amount of power to melt the aluminum to allow the gas to blow through. This is possible with modern equipment and cutting 1/2” thick aluminum plate is possible. The challenge is as always the heat dissipation. See our post on laser cutting for more information.
RE: How To Cut Aluminum Sheet Metal - Keganhirl - 02-14-2022
Use a wood-cutting saw with carbide-tipped blades to cut most aluminum. Select a fine-toothed blade and don't cut aluminum with a wall thickness of more than 1⁄4 inch (0.64 cm). If possible, choose a saw blade that creates narrow kerfs (the notch or slot made by the saw).[1]
Since aluminum does not tend to close as you cut it, create narrow kerfs whenever you can.
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Apply cutting lubricants on your blades or bits. This can range from standard oil to saw wax. Since you'll be cutting metal on metal, you want to lubricate it to prevent sparks and slippage.
WD-40 is the standard lubricant when cutting aluminum. Apply 5 to 6 small spurts on both the bottom and top halves of the blade.
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Reduce the diameter of the cutting blade for better results. The cutting speed used for wood is generally going to be too fast to safely cut aluminum. For example, if you use a 10 inch (25 cm) saw, you can reduce the blade to 7.25 inches (18.4 cm). This will slow your cutting speed.
If it's not possible to alter blade sizes, consider purchasing equipment with a variable speed router and use the slowest setting. These types of equipment are typically more expensive, but offer a degree of flexibility ideal for cutting aluminum.
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Use a C-clamp to secure your aluminum piece(s). Loosen the bar within the jaw by turning it counterclockwise. Place the clamp upright, with the open end of the jaw facing your working surface and the bottom of the jaw underneath the tabletop. Place your aluminum into the jaw and tighten the clamp around it by turning the metal rod clockwise.[2]
As an additional safety measure, use a push stick to hold and move your aluminum piece into the saw. This allows you to cut your aluminum without getting near the blades.
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Feed the aluminum through the blade, or the blade through the aluminum. Hold the saw firmly with your dominant hand. Apply downward pressure as you move the blade along your metal. Be sure to work slower than you would with wood. Steady, even pressure is the safest way to go.
Remain clear from the kickback zone (where recently cut pieces are thrown clear by the power of the saw) when cutting. This is usually directly behind the saw. Alternately, you can use a bridge to secure your saw and reduce kickback.
Always keep your fingers away from the saw blade.
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Adjust the blade depth so the blade extends 1⁄4 inch (0.64 cm) at most. Retract the blade guard and hold it beside your aluminum piece. Loosen the depth adjustment knob or lever and rotate the base of the saw until the blade is 0.25 inches (0.64 cm) below the metal at most. Afterwards, tighten the knob or lever.[3]
Always keep the power off when adjusting blade depth.
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Use a jigsaw if circular cuts need to be made in the aluminum. Clamp a guide to your aluminum on both sides of your saw. Position the saw close to the side of the aluminum where you want to begin cutting. Afterwards, lower the blade approximately 0.39 inches (0.99 cm) past the metal and guide the blade along the metal. Push the saw slowly across your aluminum piece by twisting the back of the saw into the direction opposite to the direction you want the blade to move.[4]
Keep your blade aligned with the cut line.
Always use carbide-tipped blades.
Lubricate the blade before using it, and cut slowly.
Method
2
Using a Cold Chisel
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Purchase a cold chisel that is 1 size wider than the aluminum. Use a measuring tape to determine the width of your aluminum. Afterwards, select an appropriate sized chisel. Common sizes are 1⁄4 inch (0.64 cm), 1⁄2 inch (1.3 cm), 3⁄4 inch (1.9 cm), and 1 inch (2.5 cm).[5]
For example, if your aluminum piece is 1⁄4 inch (0.64 cm) wide, use a chisel that is 1⁄2 inch (1.3 cm) wide.
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Sharpen your chisel to a 60- to 70-degree bevel using a honing guide. Fit your chisel into your honing guide (a tool that clamps onto your tool either from the sides or from above and below) and tighten the screws on both sides to keep it in place. Set the guide to the appropriate angle, and then place the bevel (the metal edge of your chisel) against a second-cut, medium-coarse file. Hold the guide with both hands and move the chisel back and forth in a thin, figure-eight pattern.[6]
Once you notice scratches on your chisel's bevel, switch to a medium grit. When new scratches begin to appear, switch to a fine grit. Wipe the bevel between each grit using a dry, clean cloth.
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Place your aluminum piece into your vice and tighten it. Position the piece in the center of the vice's jaws. Make sure that it's tightened firmly in place.[7]
Be sure to use a heavy-duty model bench vice.
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Align the chisel with your vice's screw and hammer the aluminum. Hold the chisel tip against the metal—perpendicular to it—with your non-dominant hand. Use a ball-peen hammer to strike the chisel's handle and always cut perpendicular to the jaws of the vice. Continue striking the metal until there is a notch in it. At this point, you should easily be able to snap it into 2 pieces with your hands.
You should be able to cut your aluminum metal piece within 30 seconds. Anything longer and you're probably using the wrong sized chisel, or you need to use a saw.[8]
Add 1 drop of 30-weight machine oil to the chisel's edge for lubrication. This makes it easier for your chisel to get into your aluminum's hardened grains of metal.
Never use a claw hammer—the heads are not designed for hitting hard metal and are prone to chipping.
If you're cutting a line in a sheet of aluminum, you can skip the vice and cut your way down the sheet on a flat surface. Use wood as a backing piece to help push the chisel through the metal and prevent the chisel's tip from wearing.[9]
Method
3
Cutting with Tin Snips
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Cut circles in aluminum using curve-cutting snips. Draw a circle in permanent marker on the aluminum piece. Afterwards, create a starter hole within the circle by hammering the back of a straight-blade screwdriver into the metal. Then, place your tin snips into the opening. If you're cutting counterclockwise, use red-handed offset compound snips; if you're cutting clockwise, use green-handled snips.[10]
Avoid straight-cutting snips—even if you manage to cut a circle, the hole will end up having a jagged edge.
Use both green and red snips for tough cuts. When 1 pair stops working, swap snips. Air conditioning and heating work will most likely require you to alternate between the two because they require a combination of straight and curved cuts.
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Purchase large tin snips to make straight cuts in aluminum sheets. Always open your snips as wide as possible before making a straight cut. Straight cuts are best accomplished using smooth, long strokes. As you cut, pull the cut strip upwards, and then to the side—this prevents it from sticking to the handle of your snips or blocking your handle during the cutting motion.[11]
The longer your straight cut, the longer your strokes should be.
Compound snips are designed for situations that require maneuvering as opposed to straight cuts. If you have no other option, be sure to fully open and close the snips for each stroke that you make—this will ensure maximum cut length.
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Use straight-cutting compound snips opened wide for thick metal. Be sure that the thick aluminum is straight and deep within the wide-open jaws before you make the cut. Although they aren't ideal for cutting curves, these snips are perfect for thick metals as they provide a great deal of leverage compared to other snips.[12]
Straight-cutting compound strips are most effective for doubled-up or thick sheet metal. They can typically handle a maximum of 18-gauge mild steel, which is equivalent to 0.0403 inch (0.102 cm) thick aluminum.[13]
Avoid using straight-cutting compound strips for cutting curves.