Estimated reading time: 9 minute
Precautions For Aluminum Stamping Dies
Because aluminum alloy material is softer than metal iron, expensive, easy to break, and some aluminum alloy products require subsequent processing, such as wire drawing, anodizing, etc., the aluminum plate is particularly prone to top damage and scratches during stamping production. Therefore, special attention should be paid to the following points in the manufacture of aluminum stamping dies:
- In the case of not affecting the number of projects, the punching should be arranged in the back of the project as much as possible, and even for products with a large number of punches, one more project can be considered and the punching should be arranged in the back.
- The aluminum material is soft and the mold is easier to block the material, so when designing the gap of the mold, a gap of 10% of the thickness of the bilateral material should be placed.
- When bending and forming, because the aluminum material is prone to produce aluminum scraps during bending, it will cause spot damage and indentation, so the aluminum raw material needs to be covered with PE film. In the case of rollers and electroplating, the forming block is polished and hard-plated Chrome is better.
- For stamping parts that need to be processed after anode, if the flattening and flattening process is 180°, the product cannot be completely pressed. Complete lamination will produce acid spitting, and a 0.2-0.3MM seam needs to be left to allow the acid to flow out smoothly and in time. Therefore, in this process, a limit block must be made and the mold must be calibrated higher than the mold.
- Because the aluminum material is brittle and easy to crack, especially in the case of reverse folding, try not to do crimping. Even if you want to do it, make the pressure line wider and shallower.
- All aluminum parts are required to be cut with slow-moving wire to prevent burrs and unsmooth blanking. Aluminum parts are prone to high temperature, so the hardness of the punch should be above 60°, at least with SKD11 material or above, and there should be no poor punch such as D2.
Matters Needing Attention in Aluminum Stamping Production
The aluminum material is relatively soft, so it is easy to cause top damage, crushing, scratching, and deformation during stamping production. In addition to the above requirements on the mold, the following points must be done during stamping production:
- In order to stamp aluminum parts well and reduce the defect rate, we must first do 5S, especially cleaning: the mold, punch table, assembly line and packaging materials must be free of sharp debris, no dirt and regular clear rectification, mold up and down All must be clean and free of debris.
- It is found that the burr of the product is large, and the mold must be sent for repair in time and the result should be followed up.
- Aluminum parts are easy to heat up and become hard when they are stacked together. Therefore, when punching and blanking, it is necessary to apply some pressing oil on the material (which can not only dissipate heat, but also smooth the blanking) and then punch.
- Products with more punching holes need to be punched and the surface of the mold should be cleaned. To ensure that the molds and products are always clean and free of debris, reducing top damage. If the top damage is found, the problem point of the mold top damage must be found and solved before production can continue.
- Flattening the die push block will produce aluminum scraps, so after the push block is produced every day, the aluminum scrap under the push block must be cleaned.
Aluminum Alloy Characteristics And Classification
The analysis of aluminum alloy materials here takes the automotive parts stamping industry as an example.
The aluminum-alloy body is mainly composed of 5 series and 6 series aluminum alloy materials. The performance characteristics of the inner panel material require good formability, high plasticity, and good connectivity. The 5 series aluminum alloy and some 6 series aluminum alloys are mainly used. For automobile outer panels, good plasticity is more conducive to forming, so 6 series aluminum alloys are widely used in outer panels according to their heat-treatable strengthening properties. The alloys and process characteristics contained in them are shown in the table below. The most widely used grades of aluminum alloy body are: AA6016, AA6022, AA6005, AA6009, etc. Most of the 6 series is used in the outer cover; 5 series such as AA5754, AA5052 are mostly used in the inner plate. For example, Chrysler Hunter uses 6022 aluminum alloy as outer cover material, Acura NSX uses 5052 aluminum alloy as inner panel material and 6 series aluminum alloy as outer cover material.
|Model||Alloying Element||Process Features|
|5xxx||Al-Mg||No heat treatment strengthening, low strength, good plastic deformation ability.|
|6xxx||Al-Mg-Si||It can be strengthened by heat treatment, with moderate strength, good stamping and forming performance, good corrosion resistance, easy to paint and color, and good comprehensive performance.|
Process Planning Characteristics of Steel And Aluminum Stamping Workshop
At present, most mainstream factories use steel-aluminum mixed line production, and the workshop process layout is roughly the same as that of traditional steel plate stamping workshops. According to the production characteristics of aluminum alloys and the production requirements of the workshop, its characteristics are mainly reflected in the following aspects.
Difference From Traditional Stamping Process
According to different material properties, aluminum alloy plates have their own characteristics in production line design, rework and grinding mold use, and application of waste collection. Table 2 shows the comparison of stamping processes between steel plates and aluminum plates. In the process planning of the aluminum alloy stamping workshop, many different factors should be combined, and the production line body should be flexibly set according to the actual steel-aluminum mixed line and the needs of the planned production capacity to meet the switching of steel and aluminum in the production process.
|Traditional car steel plate||Aluminum alloy plate|
|Material||Galvanized steel.||5 series, 6 series aluminum alloy.|
|Performance||Stable performance.||The performance is lively, easy to oxidize, and it is easy to corrode when it comes into contact with steel. Before production, the suction cup and belt should be thoroughly cleaned to prevent the aluminum plate from being scratched by iron filings, or attached to the aluminum plate to produce pits or bumps.|
|Press line||The mainstream is dominated by four-sequence formation.||It is recommended to form in five orders.|
|Sheet separation||Magnetic separation.||Air knife split.|
|Sheet transport||Ordinary belt.||Vacuum belt.|
|Cleaning, oiling||Can be cleaned and oiled offline.||The cleanliness requirements are very high, and it must be cleaned and oiled online.|
|Polishing||No special requirements.||Grinding; the aluminum scraps produced by the aluminum plate need to be collected and processed in the grinding room. The grinding room should be ventilated frequently, and it should be fireproof and explosion-proof.|
|Mold||Due to the different forming properties of materials and different parameters such as spring back, the molds of the parts cannot be universal.|
|Waste||Waste conveying, collection need to be completely separated.|
The Setting of Aluminum Plate Rework And Grinding Room
When the aluminum plate is reworked and polished, a large amount of powder will be generated. When the powder concentration in the space is high, there will be a danger of explosion. It is generally believed that the explosion risk is greater when the concentration reaches 30g/m3, so the aluminum plate grinding room needs to be explosion-proof.
- According to the characteristics of the aluminum dust itself, the dust should generally be collected in a centralized manner for pressure relief and decompression treatment. In addition, the aluminum powder grinding room needs to be isolated from the production area.
- Aluminum plate grinding requires a closed grinding room and a complete dust removal system. The grinding room is closed to isolate the outside world from the grinding work area to isolate sparks and dust from the outside world, and the dust removal system is used to reduce the dust concentration in the grinding room.
- The ventilation frequency in the grinding room is not less than 50 times/h, and the wind speed in the pipeline is not less than 20m/s. To ensure that the dust concentration in the grinding area will not reach the concentration limit and cause an explosion.
- Generally, dust explosions occur in dust collectors. When an explosion occurs, a strong shock wave will be generated. The dust in the pipeline will be raised by the shock wave and diffused. The diffused dust will be transmitted back to the factory building, which will cause a secondary explosion in the factory building. Therefore, it is necessary to add an explosion-proof isolation valve to isolate the diffusion of dust in the pipeline, and isolate the grinding work area from the explosion area. When the dust collector explodes, it should be vented to the open area outside the workshop.
Storage And Maintenance of Aluminum Plates
Based on the active characteristics of the aluminum plate material, when storing the aluminum plate, it is necessary to pay attention to the impact of the oxidation and damage of the aluminum plate on the subsequent production and strengthen the maintenance of the aluminum plate before production to ensure the yield of the product during the production process.
- After the aluminum plate material fails and hardens, the yield strength will increase and the plasticity will decrease, which will affect the subsequent forming and hemming. It is necessary to comprehensively consider the plasticity requirements of the material during mold manufacturing. Before production, it is necessary to check whether the state of the material meets the production requirements.
- The aluminum plate material should be used immediately after unpacking. Before use, it should be cleaned and oiled online. The drawing oil should meet the requirements of aluminum plate forming.
- Because the aluminum plate is easy to be oxidized, it needs to be packed tightly and cannot be placed outside. The hardness of the aluminum plate is lower than that of the steel plate, so it is easy to be scratched and bruised, so special attention should be paid during handling; in addition, the outer plate parts cannot be stacked and stored, and need to be transported on a pallet, and the contact area between the bracket of the pallet and the aluminum plate should be small. , and ensure clean and soft requirements.
In view of the more and more common situation of aluminum plate stamping application, according to the characteristics of the aluminum plate itself, in the process planning of the stamping workshop, the steel and aluminum mixed line setting, the collection of steel and aluminum plate waste, the setting of the aluminum plate rework and grinding room, and the storage and maintenance of the aluminum plate should be comprehensively implemented. Considering that it is used to improve the efficiency of aluminum plate production and improve the flexible layout of the stamping workshop, it is conducive to the reasonable and efficient operation of the stamping workshop equipment.