Research on the production process of 8011 aluminum foil blanks
8011 aluminum foil blanks are widely used in the production of medicine foil, household foil, and wine label foil.
In recent years, with the rapid development of my country's national economy and the general improvement of people's living standards, the demand for 8011 aluminum foil in various industries in the market has increased year by year.
The development of rolling technology has enabled most domestic aluminum foil manufacturers to be equipped with wide-width aluminum foil rolling mills, with rolling speeds as high as 800-1500m/min and a single roll weight of up to about 20t.
The production efficiency of aluminum foil has been greatly improved, and the domestic wide-width aluminum foil blank market is in short supply.
Taking the production of 8011 aluminum foil blanks as an example, this paper discusses the problems and improvement measures in the production process
1. Strictly control the metallurgical quality of incoming materials
1.1 During the smelting process of billets, the hydrogen content of the melt is required to be no more than 0.12ml/100gAl, and a combination of furnace refining and degassing is adopted with launder online degassing.
1.2 The amount of non-metallic inclusions in the melt does not exceed 100ppm, and a ceramic plate double-stage filtration with an accuracy of no less than 30 ppi is used during casting.
1.3 Pay attention to adjusting the amount of alloy elements added to meet the iron-silicon ratio requirements, and select reasonable smelting and casting temperatures to ensure that the casting grain size reaches the first level, so as to prevent the coarse grains from increasing the number of pinholes and the number of belt breaks during aluminum foil rolling, and affecting the surface quality.
Below is the chemical composition table of 8011 aluminum foil based on commonly used standards, primarily referring to China's GB/T 3190, the U.S. Aluminum Association (AA), and related sources:
Chemical Composition of 8011 Aluminum Foil (Weight Percent %)
| Element | Content Range (%) | Description |
|---|---|---|
| Al | Balance | Main element |
| Fe | 0.60 – 1.00 | Enhances strength, partially replaces Mn |
| Si | 0.50 – 0.90 | Improves castability and corrosion resistance |
| Cu | ≤ 0.10 | Kept low to improve corrosion resistance |
| Mn | ≤ 0.20 | Adjusts microstructure with Fe |
| Mg | ≤ 0.05 | Generally not added, very low content |
| Zn | ≤ 0.10 | Controlled as impurity |
| Ti | ≤ 0.08 | Refines grain structure |
| Cr | ≤ 0.05 | Impurity control |
| Others (individual) | ≤ 0.05 | Trace impurities |
| Others (total) | ≤ 0.15 | Total of all unspecified elements |
2. Improve the level of plate shape control
2.1 Taking the production of a certain factory as an example, adjust the roll type parameters of the working roll of the 2400 hot rolling mill, optimize the rolling pass, improve the emulsion lubrication cooling capacity, and control the convexity of the incoming hot rolled coil between 0 and 1%.
2.2 When the 2050 six-roller cold rough rolling mill is opened, the overlap of the intermediate support rolls on the display is corrected by the measured data to ensure that the force arms at both ends of the intermediate roll bending force are consistent and eliminate the single-sided rib waves during the opening and rolling.
Previously, we have checked the problems in the spraying, and the spray flow, pressure, and nozzle opening and closing are under control.
Combined with the high-speed operation of the 2050 cold rolling mill, we have standardized the use of the intermediate roll and working roll bending rolls, which can effectively eliminate the M-type composite waves with loose middle and loose sides and the W-type waves with loose ribs.
The optimization of the pass processing rate and tension parameters also ensures the plate shape in the cold rolling opening stage.
2.3 After intermediate annealing, the 8011 aluminum foil blank is rolled in the 2000 cold finishing mill. Under the condition of ensuring the normal lubrication and cooling capacity of the rolling oil, the target plate shape parameters are appropriately selected to ensure that the convexity in the incoming cross section and the roll gap shape controlled by the plate shape parameters are consistent.
The purpose is to ensure that the cross section of the slab is deformed in the same proportion at all places to ensure high-quality plate shape.
In addition, we have optimized the combination of the 2000 rolling mill support roll, the original roll shape of the working roll and the grinding cut-in angle of the working roll, which can ensure that the online plate shape of the aluminum foil billet reaches 30I, and the plate shape after over-tension correction can reach less than 101 after offline.
3. Control the thickness deviation of 8011 aluminum foil blank
Prevent excessive fluctuations in process parameters such as tension, speed, and rolling force during aluminum foil rolling, resulting in poor plate shape and broken strips.
For this reason, we require that the slope of billet thickness fluctuations be less than 0.04mm/100mm, the convexity of cast and hot-rolled plates and the difference between the same plates should not exceed 1% of the thickness, and there should be no M-shaped distribution.
The longitudinal thickness difference of 8011 aluminum foil blanks after they are off the line is not greater than ±2% of the plate thickness, and the frequency of thickness fluctuations should be less than the response frequency of thickness adjustment control.
We have fine-tuned the thickness adjustment control system, requiring AGC to be put into monitoring as soon as possible during operation, the speed increase and decrease transition of the head and tail is smooth, and no major adjustments are made to the process parameters during stable rolling.
4. Control the quality of billet trimming
4.1 When trimming the middle of the rewinder, ensure that the cracked edge is cut cleanly to meet the normal rolling of the subsequent pass.
For this reason, the 2050 rolling mill is required to have loose materials on both sides to prevent the cracked edge from aggravating.
In addition, increasing the trimming thickness is conducive to cutting the cracked edge cleanly. The reserved trimming amount during the middle trimming should be large to prevent the rolling shrinkage from being too large after annealing, which will affect the quality of the straightening trimming.
4.2 When the finished 8011 aluminum foil blank is trimmed during the straightening, the single-side trimming amount should be reserved not less than 10-15mm, which can increase the trimming speed.
Production practice shows that a large shearing gap is prone to curling and burrs, and a small shearing gap is prone to gnawing.
A large overlap cannot cut the edge strip, and a small overlap is prone to curling and ruffles. Through experiments, it is confirmed that the shearing gap is 0.001-0.005mm, the overlap is 0.2-0.5 ram, and the trimming quality is good.
By precisely adjusting the overlap of the disc cutters and the gap between the cutting blades, the cutting quality is guaranteed to be smooth and burr-free, and the edges are bright enough to reflect the image.
5. Improve surface quality
5.1 Ensure that the unwinding tension of the next process is not greater than the winding tension of the previous process to prevent scratches caused by interlayer displacement.
5.2 Always keep the guide rollers and guide paths clean to prevent roller marks and bright lines.
5.3 Select a reasonable pass processing rate, increase the oil supply pressure in the finished pass, ensure the filtering effect of the rolling oil, and avoid color difference and hot pressing stripes on the plate surface.
5.4 Wipe the lower edge of the exhaust hood in the finished pass, remove high-viscosity miscellaneous oil, clean the flattening roller, and prevent oil stains that cannot be washed off from the plate surface.
6. Improve the mechanical properties of billets
Increase the hot rolling final rolling temperature, improve the intermediate annealing process and the processing rate after annealing, and improve the mechanical properties of billets.
6.1 When hot-rolled materials are opened, organize production reasonably, optimize process parameters, shorten the rolling time of a single ingot, increase the final rolling temperature to above 300℃, and make the recrystallization structure inside the hot-rolled coil as fine and uniform as possible.
6.2 According to the different internal structures of hot-rolled materials and cast-rolled materials, adjust the intermediate annealing temperature and time to ensure that the grain size is restored to the first level after annealing, the grain size is uniform, and as much a (A1FeSi) phase as possible is precipitated in the internal structure, and the degree of work hardening and pinhole degree during aluminum foil rolling are reduced.
Annealing Performance Comparison of 8011 Aluminum Foil: CC vs. DC
| Item | CC 8011 (Continuous Casting) | DC 8011 (Direct Casting) | Notes |
|---|---|---|---|
| Annealing Temp. Range | 250–350℃ | 300–400℃ | CC has coarser grains, requiring slightly lower temperature |
| Annealing Time | 2–4 hours | 2–3 hours | Slight adjustment based on thickness and equipment |
| Softening Capability (O temper) | Good, but slightly inferior to DC | Excellent, fully softened | DC softens more completely with less residual stress |
| Post-Annealing Structure | Coarser, banded, visible segregation | Uniform, dense, fine-grained | DC structure is more suitable for deep processing |
| Strength Stability | Prone to fluctuation | Stable | Related to initial structure and processing uniformity |
| Elongation (Annealed) | Slightly lower (15–18%) | Higher (18–22%) | DC provides better ductility |
| Pinhole Tendency | Higher | Lower | DC performs better in deep drawing |
| Typical Applications | Food packaging foil, cable wrap foil | Pharmaceutical foil, electronic foil, premium packaging foil | Match application according to performance |
Summary:
- CC 8011 Aluminum Foil: Offers acceptable annealing and softening performance, suitable for general applications such as food packaging and cable wrap.
- DC 8011 Aluminum Foil: Provides more stable performance and uniform structure after annealing, making it ideal for high-performance applications like pharmaceutical and electronic foils.
6.3 Adjust the processing rate after annealing to improve the strength and plasticity of billets to meet the needs of rolling.
The key factor to be controlled during the production process of 8011 aluminum foil blank is to improve the metallurgical quality. Secondly, attention should be paid to controlling the plate shape, reducing the thickness deviation, improving the trimming quality, surface quality and mechanical properties, and finally producing high-quality aluminum foil products.