Make a 90 Degree Bend in a Piece of Sheet Metal Aluminum
In the aircraft fields today, sheet metal bends are one of many important structures that help create the perfect flying machine. There are a variety of bends that contribute to the aircraft's body to ensure it can handle any loads it will eventually encounter. For example, having to land, having to fly through gusts of heavy wind, or even having to maneuver the plane. Aluminum bends are also found within the aircraft to help block off parts of the plane, for instance, patches between the empennage and fuselage. The aluminum bends are very useful in generating a unique shape, and have been used to make airplanes for a very long time. So this article shows you how to make a 90 degree bend in a piece of sheet metal, using the tools that most aircraft maintenance workers use in the field.
Contents
Steps
- Take a piece using these dimensions as shown above.
- Cut a piece of sheet metal, 2 X 4 inches, .040 material thickness and a Bend Radius of .375. You will do this by taking any size piece (a relatively good size) and putting it in the cutting machine. But before you cut your piece, you need to first take a 6" ruler and mark out your 2 X 4 inch measurements. Afterwards, take your piece over to the cutting machine. Place it in according to your measurements, press down with your foot, and it will cut the aluminum. Next, take your piece and lay it out on a table in front of you. Take a single-cut file and deburr all the sides and corners of your piece, so it's easier to work with.
- Mark down a few important measurements on your piece of metal. Before you mark anything though, make sure that the grain traveling on your piece is moving in the opposite direction from when you bend it. Meaning it will be traveling lengthwise. The next few markings that you will put on your piece are important reference points for when you bend the aluminum.
- Mark down your Bend Tangent Lines. These lines are where your bend will begin and end. To figure out your Bend Tangent Lines, you will need to figure out your Setback.
- Setback is defined as the distance from your Bend Tangent Line to your Mold Line. To find Setback, you add your material thickness and the radius of your bend, times your K value(your angle, 90 degrees). In this case, (.040 + .375)1.0000. You will get an answer of .415. Now take the 2" measurement that we already know from flat side A, and starting from your center line, subtract .415 from it. You will get an answer of 1.585" which you can measure with your 6" ruler. Mark it down on your piece of metal. This marks your first Bend Tangent line.
- Calculate your Bend Allowance. The Bend Allowance is defined as the amount of material used for the bend, and is determined by using the following formula: BA= (0.0173(BR) + 0.0078(MT)). For bends 1-180 degrees, this formula is used. Inputting our values into the equation, we end up with an answer of .617. The use of a table can also help us find Bend Allowance. Now measure .617 from your first Bend Tangent line, then mark it. Draw another line which will give you your second Bend Tangent line.
- Lastly, you will need to mark your sight line. A sight line is your Bend Radius measured from the Bend Tangent line that's closest to the end going in the brake. Soon when we'll place your piece in the brake, you will place the radius in until it reaches the edge of your sight line. This will ensure the bend is in the right spot for the perfect bend. Next, Measure your Bend Radius, .375, from the Bend Tangent line closest to the edge of the metal entering the brake. Mark it with a dotted line, to tell it apart from your Bend Tangent lines. Once that is complete, you are now ready to bend your piece of sheet metal!
- Walk over to the brake. You will need to set the brake in order to bend your piece of sheet metal. Place your piece upward in the brake. Adjusting the handles behind the brake and the handles on the clamping bar, will slowly start to move and tighten around your piece. Continue to do so until you can't pull out your piece of sheet metal.
- Lift the clamping bar, then slide your piece in underneath your radius. Slide it under until you reach your sight line. Look down or use your 6" ruler to make sure your sight line is directly under your radius. Clamp down the bar to tighten your piece in place.
- Slowly lift up the folding leaf to start bending. You will need to lift up the folding leaf far enough so your piece passes the 90 degree mark. You need to do this in order to avoid spring back. If you were to just bend it to the 90 degree mark and take it out, your piece of metal would slowly bend backwards and you would need to bend it again. So in order to save you from that trouble, we will bend the piece of sheet metal further to ensure it will come out 90 degrees.
- Once you have bent the piece of sheet metal, put down the folding leaf to its original spot and lift up the clamping bar. Take out your piece and walk over to a flat surface. Place your piece flat on each side and measure with your 6" ruler to see if it's a perfect 90 degree angle. If your piece happens to be a bit past the 90 degrees, pull it back a bit then measure it again. Congrats! You have now created a 90 degree bend in a piece of sheet metal.
Tips
- Have a handy, small 6" ruler
Warnings
- Remember when dealing with these machines like the brake and cutting brake, to keep your fingers away from the sharp cutting/bending edges. They are known to cut through tough material like your finger!
- Remember to set your brake before you start bending.
- Make sure your grain is traveling in the opposite direction of your bend.
