The last of the four mechanical forming processes, drawing, is one of the processes discussed in the following video (4:45) on How are Aluminum Cans Made? While you are watching this video, please think back, way back, to Lesson 1 of this course and the reading in the textbook about different materials used for carbonated beverage containers. And remember to look for the drawing operation (hint: it is the operation that gives the can its height).
The next time you buy a can of soft drink consider this: the aluminum tin can will always be recyclable. Unlike plastic, aluminum never deteriorates no matter how often it's melted down and used again. Aluminum cans are so lightweight, that it's hard to believe that they're made from a huge roll of our minyan sheeting that weighs nine tons. The sheet is about a meter and a half wide and a roll like this is long enough to make three-quarters of a million drink counts. The sheet feeds into a press that punches out round pieces that will be formed into counts. The punch press actually performs two operations it punches out a disc 14 centimeters in diameter then bends it into a cup. What's left of the sheet gets compacted and sent back to the aluminum factory where it's recycled into new rolls. The cup goes into a machine of the draw and iron body maker. A tool draws out the aluminum forming the body of the camp. The tool is lubricated, so it won't tear the aluminum while stretching it. The lubricant also acts as a coolant because the aluminum heats up as it's being worked. Once the body is formed a trimmer cleans and straightens the edges. Now the cans move along upside down on the conveyor belt over to the washer. The washer performs a six-stage cleaning. The first two washes are in hydrofluoric acid at 60 degrees Celsius. The last four washes are in deionized water neutral water with no pH also at 60 degrees. The cans come out of the washer and go under the hot air dryer. They're now shiny because the hydrofluoric acid wash removed a thin surface layer of aluminum.
Next, a roller passes over the cans coating the bottom rims with varnish. This coating allows the cans to slide easily on conveyor belts and in vending machines and shows up as a blue ring under an ultraviolet light. The cans are now ready to be printed this rotation printing system can apply up to five colors one at a time. Then a layer of varnish is applied to protect the ink. Even in slow motion, it's a high-speed operation, and here's the actual speed: 1800 cans per minute. Next, the cans fly through an oven that instantly hardens the ink and dries the protective varnish. Next, the Machine sprays a water-based varnish on the inside of the cans. This creates a barrier between the drink and the aluminum so the drink won't end up tasting like metal. It also prevents the aluminum from being eaten away from the inside by the acid in carbonated drinks. Next, the cans go through a machine called the Nekor which forms a 5-centimeter neck on the can. This is done gradually in 11 steps so as not to puncture the paper thin aluminum.
The next machine called the flanger forms a curved over the edge at the top of the camp which will later attach to the pull tab cover. The cans pass through a sophisticated vision system that photographs the inside of each can any can that doesn't meet standards, that has a bump or some ink inside is sent back for recycling. From here, they're shipped to the drinks company which fills them and then attaches the pull tab cover. So, now you know. You can start the whole process off by recycling your cans.
Now that we have reviewed the four mechanical forming processes for metals: forging, rolling, extruding, and drawing, hopefully, you also understand why I refer to them as pounding, rolling, pushing, and pulling. In the next section, we will look at how metals that cannot be mechanically formed are typically formed.