The choice of aluminum plate seems like just moving a metal plate from point A to point B. However, those who have actually done it know that there are more ways to go than you think. You may have encountered this situation: all the aluminum plates you purchased are aluminum plates. Some will crack after being bent, some will be deformed after welding, and some will start to peel after being left outdoors for a month. Don't panic, you are not the only one encountering these problems.
Let’s start with the basics. There are many names for aluminum plates. Some people call them aluminum sheets, and some people call them aluminum skins. However, no matter how you call them, the material condition is the first thing you need to understand. Common materials of aluminum plates include pure aluminum series, aluminum-manganese series, aluminum-magnesium series, etc. Pure aluminum is relatively soft and is suitable for making parts that do not require stress. The hardness of the aluminum-manganese series has been improved and can be used to create simple cabinet structures. The aluminum-magnesium series has higher strength and good corrosion resistance, and is a common choice in outdoor applications.
Let us take an example to illustrate the problems that may arise if the wrong material is selected. There is a company engaged in the production of outdoor signage. When the first batch of products was made, pure aluminum plates were chosen because the price of pure aluminum plates was low and the supplier had ample inventory. Everything goes smoothly during cutting and bending operations in the workshop, thanks to the excellent machining properties of pure aluminum. However, the problem occurred three months later. Customers reported that the surface of the signboard installed in the open air began to show white spots, and powder would fall off when rubbed with the hand. This is a typical corrosion phenomenon. In humid and polluted air, the corrosion resistance of pure aluminum is relatively weak. The oxide film formed on its surface is not dense enough, and it will be corroded by the surrounding environment over time. If aluminum-magnesium alloy plates had been chosen, the situation would have been completely different.
First, how to judge what kind of material you need? This needs to be considered based on the environment in which your product is used. If your product is indoors most of the time and does not come into contact with water or corrosive gases, then pure aluminum or aluminum-manganese series will be enough. If your product needs to be placed outdoors, especially in coastal areas and industrial areas, then the aluminum-magnesium series will be more suitable. In addition, the processing method must be considered. The requirements for materials such as bending, welding, and stamping are different. If there is a need for deep drawing and deep processing, you have to choose a material with high elongation. In this case, pure aluminum is better than high-strength aluminum alloy.
Next, let’s talk about the issue of thickness. The thickness of aluminum plates is usually expressed in millimeters, which ranges from 0.2 millimeters to tens of millimeters. Many people think that the thickness is just enough. However, this enough actually covers many dimensions. If the thickness is too thin, it will lead to a lack of structural strength, and the product is prone to deformation during use. If the thickness is too thick, it will increase cost and weight, and some processing equipment cannot handle plates that are too thick. You have to find a balance between the two.
There is a piece of common sense about dimensions that many people don’t know. The standard widths of aluminum plates are usually 1000 mm, 1219 mm, 1250 mm, and 1500 mm. If the size of the parts you design happens to meet the division method of the standard plate, then Then there will be very little waste during cutting, so the material utilization rate will be high and the unit price will naturally be lower. On the contrary, if you insist on a non-standard width, then either buy the entire plate and cut off most of it, or go for custom-rolling. Both of these methods will cause the cost to rise significantly.
"Surface treatment" is another aspect that is easily overlooked. Aluminum plates are in many different states when they leave the factory. Some have protective films on their surfaces, some have been chemically treated, and some are completely blank. Aluminum plates with protective films are suitable for situations where subsequent stamping and bending operations are still required. The reason is that the protective film can avoid the need for processing. If the surface is scratched during the process, chemically treated boards are generally called chromated boards or passivated boards. There is a conversion film on the surface of such boards, which can be directly sprayed or pasted with composite materials. There is a thin oxide layer and oil on the surface of a completely blank aluminum plate. It must be cleaned and degreased before any surface treatment.
After you understand these basic knowledge, you may find that many problems can actually be solved at the material selection stage. Next, we have sorted out some of the most common questions and presented them in the form of questions and answers so that you can quickly find the answers.
Q: What should I do if the aluminum plate cracks when I bend it?
Please replace it with a plate in the O state or the H2X state. The H18 state is too hard to be bent, so it needs to be annealed before processing.
Q: Can scratches on the surface of aluminum plates be removed?
A: Shallow scratches can be removed by polishing along the lines with a scouring pad. Deep scratches will affect the appearance, which requires re-surface treatment.
Q: Is it normal for different batches of aluminum plates to have different colors?
A: In normal condition. Color difference will occur during anodizing or spraying. For important parts, it is recommended to purchase all required materials at one time.
Q: Can aluminum plates be used in direct contact with stainless steel?
A said that this is not recommended because once the two metals come into contact with each other, the corrosion rate of the aluminum plate will be accelerated, so an insulating gasket or isolation layer needs to be added between them.
Q: How to easily determine whether the aluminum plate material is correct?
A: Take a file and file it, and then check the chips. The chips produced by pure aluminum are continuous, while the chips produced by hard aluminum are in the form of powder.
Let’s look back and forth at the key points just discussed. First, the selection of materials should be determined based on the environment in which they are used and the way they are processed. It is not that harder is better, nor that softer is more cost-effective. Secondly, standard specifications need to be considered for thickness and size, which can reduce procurement costs and reduce processing troubles. Third, the state of the surface treatment determines the convenience of subsequent processing. If you confirm clearly in advance, you can save a lot of intermediate steps.
Here are some concrete, actionable suggestions for your next procurement or design work. Before getting the quotation from the supplier, you should ask about the material grade and status in advance. It is necessary to confirm the thickness tolerance range, because there are great differences between the control levels of different manufacturers. If you plan to do bending or welding, it is best to get a small sample for trial processing. Finally, keep the material certification documents so that you can have records in case any problems arise.
Aluminum plates are complicated because different application scenarios correspond to different optimal options. If they are simple, as long as you understand a few key nodes, most problems will not arise. I hope what I talked about today can help you avoid some detours and devote your time and energy to what is really important.
