I recall distinctly my initial knowledge about creating a die that had been designed to die casting china right into a deep, contoured shape. Being unsure of much about aluminum, I assumed that it should be extremely formable-after all, they are beverage cans from it, don’t they?
My first thoughts were, “This can be a cake walk. I’ll bet this stuff stretches a mile. Yep, it has to stretch a great deal because it’s really soft.”
This thought process was obviously a testimony to my ignorance regarding aluminum.
I believe I lost a big percentage of my hair working to make that job work. I have to have spent weeks fighting splits and wrinkles. It wasn’t long before I got to the conclusion that drawing and stretching aluminum were not as simple as I needed thought.
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Now that I am a little bit wiser with regards to the formability of aluminum and aluminum alloys, I know that my problem really was not the fault of your aluminum, but instead the fact that through the die tryout stages, I used to be thinking like steel as opposed to aluminum. Up until then, everything i would have done to correct the trouble having a die which was forming steel, I did together with the aluminum. Needless to say, I failed.
To be honest that aluminum is not really steel. It doesn’t behave like steel, it doesn’t flow like steel, and it certainly doesn’t stretch like steel. So can this make aluminum challenging to form? No, not if you believe like aluminum.
Aluminum is not a bad metal; it’s merely a different metal. Like all metal, it has positives and negatives, and the bottom line is to learn the material’s behavior before designing a part or creating the procedure and die which can be to produce it.
In case you are comparing aluminum to deep-drawing steel, generally you will notice that aluminum lacks near the elongation ability of steel. For example, typical deep-drawing steel has elongation somewhere around 45 percent, while a 3003-O temper, meaning “dead soft,” aluminum could have elongation near 30 percent.
In most cases and dependant upon the alloy, aluminum has poor stretch distribution characteristics in comparison to deep-drawing steel. It is regarded as a material that strains locally, meaning that most of the stretch that happens when the metal is exposed to a stretching operation will take place in a tiny, localized area.
However, remember that the forming punch geometry includes a greater influence on how the metal stretches compared to the metal itself. Stamped parts to be made from aluminum should be designed so that the part shape forces the metal to distribute stretch more evenly.
Aluminum ironing process
Figure 2Generally speaking, aluminum is a superb material when ironing works extremely well. During ironing, the metal is squeezed down a vertical wall to increase the surface area while lowering the metal’s thickness. Ironing is definitely the basic process employed to make beverage cans.
Parts requiring significant amounts of stretch in a small area with small male radii are doomed to fail if designed of aluminum, especially if the final geometry is usually to be made in just one forming operation. On the other hand, large, liberal radii and flowing, gentle geometries are the best-suited for aluminum.
First, don’t confuse drawability with stretchability. Drawability will be the metal’s power to flow plastically when exposed to tension, while stretchability is definitely the increase of surface area due to tension.
According to the type, aluminum can draw adequately (see Figure 1). It possesses a good strength-to-weight ratio and is well-suited to the deep-drawing process, and also multiple draw reductions. The reductions percentages are very similar to those often used when drawing deep-drawing steel.
Although aluminum is soft, it can nevertheless be abrasive. While it does not rust conventionally, it forms a white powdery substance called aluminum oxide, which is used to make 10dexppky wheels. Which means exactly the same abrasive that you may have been using to grind your tool steel die sections might be present in the aluminum sheet surface.
You are able to prevent this poor interface by making use of high-pressure barrier lubricants, which keep your aluminum from touching the tool steel sections during forming and cutting.
Generally speaking, aluminum is an excellent material when ironing may be used. During ironing, the metal is squeezed down a vertical wall to boost the surface area while reducing the metal’s thickness. It increases the metal sheet’s surface area by squeezing the metal as an alternative to exposing it to tension. Ironing may be the basic process accustomed to make beverage cans (seeFigure 2).
When aluminum is ironed, it almost compressively flows just like a hot liquid across the wall of your die cavity and punch, and it shines into a mirrorlike surface finish.
Aluminum has more springback than soft draw-quality steel. However, the amount of springback that occurs can be controlled by designing the stamped product with respect to the springback value.