How to control the dimensional accuracy in the production of aluminum profiles?

December 24, 2024

In the process of aluminum profile production, controlling dimensional accuracy is a key link to ensure product quality. The following are some methods for controlling dimensional accuracy:

1、 Mold design and manufacturing

Rationality of mold design

Accurate cavity size design: When designing the mold cavity, precise calculations should be made based on the target size of the aluminum profile. Considering the shrinkage rate of aluminum profiles during cooling, it is usually necessary to appropriately enlarge the cavity size. For example, the shrinkage rate of aluminum profiles with different alloy compositions varies. The shrinkage rate of 6063 aluminum alloy profiles is generally between 0.8% and 1.2%. This factor should be taken into account when designing the mold cavity size to ensure that the extruded aluminum profile size meets the requirements.

Reasonable design of diversion holes and channels: The layout and size of diversion holes and channels directly affect the flow uniformity of aluminum liquid in the mold. Reasonable design can evenly fill the mold cavity with aluminum liquid, avoiding dimensional deviation of profiles caused by uneven flow. For example, multiple diversion holes are used and symmetrically distributed, while optimizing the shape and size of the diversion groove to ensure uniform pressure and flow velocity of the aluminum liquid when entering the mold cavity.

Precision control in mold manufacturing

The use of high-precision machining equipment: high-precision CNC machining equipment is used to manufacture molds, such as CNC machining centers, electrical discharge machining machines, etc. These devices can accurately process various parts of the mold, ensuring the dimensional accuracy and surface quality of the mold. For example, CNC machining centers can control the dimensional accuracy of molds within ± 0.01mm, effectively reducing the dimensional deviation of aluminum profiles caused by mold manufacturing errors.

Inspection and correction during mold manufacturing process: Multiple inspections are required during the mold manufacturing process. For example, conducting a dimension check after rough machining and adjusting the machining allowance based on the test results; After precision machining, the key dimensions of the mold are comprehensively inspected using precision testing equipment such as coordinate measuring instruments. If any dimensional deviation is found, it should be corrected in a timely manner to ensure that the final dimensional accuracy of the mold meets the design requirements.

2、 Extrusion process stage

Quality and Dimensional Control of Aluminum Rod

Selection of high-quality aluminum bars: Choose aluminum bars with good quality and high dimensional accuracy as raw materials. The diameter tolerance of the aluminum rod should meet the requirements, generally requiring the diameter tolerance of the aluminum rod to be controlled within ± 0.5mm. If the diameter deviation of the aluminum rod is too large, it will affect the filling of the aluminum liquid in the mold, leading to unstable dimensions of the aluminum profile.

Pre treatment of aluminum rod: Before extrusion, the aluminum rod is subjected to homogenization treatment and heating. Homogenization treatment can make the internal structure of aluminum bars uniform and reduce the size changes of profiles caused by uneven structure. The heating temperature should be strictly controlled. Aluminum bars with different alloy compositions have different heating temperatures. For example, the heating temperature of 6061 aluminum alloy bars is generally between 480-520 ℃. The appropriate heating temperature can ensure the fluidity of the aluminum liquid and facilitate the extrusion of aluminum profiles with precise dimensions.

Squeezing speed and pressure control

Reasonable adjustment of extrusion speed: Extrusion speed has a significant impact on the dimensional accuracy of aluminum profiles. If the speed is too fast, the flow state of the aluminum liquid in the mold is difficult to control, which can easily generate eddies and turbulence, leading to dimensional deviations in the profile; If the speed is too slow, it will affect production efficiency. In actual production, the extrusion speed should be adjusted reasonably based on factors such as the shape, size, and alloy composition of the aluminum profile. For example, for aluminum profiles with complex cross-sections, the extrusion speed is generally controlled between 5-10m/min to ensure that the aluminum liquid can evenly fill the mold cavity.

Accurate control of extrusion pressure: The magnitude of extrusion pressure directly affects the forming quality of aluminum profiles. Insufficient pressure may prevent aluminum profiles from completely filling the mold cavity, resulting in insufficient dimensions; Excessive pressure may cause deformation of the mold, affecting the dimensional accuracy of the profile. Accurately control the extrusion pressure through pressure sensors and control systems, and adjust it according to the requirements of different molds and aluminum profiles. For example, for the extrusion of large aluminum profiles, the pressure is generally controlled between 20-30 MPa.

3、 Cooling and traction process

Cooling method and speed control

Choose the appropriate cooling method: Aluminum profiles are usually cooled by air or water cooling after extrusion. The air cooling speed is relatively slow, making it suitable for aluminum profiles that do not require particularly high dimensional accuracy; Water cooling has a fast cooling speed, but if not controlled properly, it may cause deformation of the profile due to uneven cooling. For aluminum profiles with high dimensional accuracy requirements, a mixed cooling method of air cooling followed by water cooling can be used. For example, after extruding aluminum profiles, a brief air cooling is performed to preliminarily solidify the surface of the profile, followed by water cooling, which can effectively reduce cooling deformation.

Uniformity control of cooling rate: Whether it is air-cooled or water-cooled, it is necessary to ensure uniform cooling rate. When air-cooled, it is necessary to ensure the stability and uniformity of the air source, so that all parts of the profile are subjected to the same wind force; During water cooling, it is important to control the temperature, flow rate, and spray angle of the cooling water to avoid rapid local cooling of the profile. For example, the temperature of the cooling water is generally controlled between 20-30 ℃, and the flow rate should be adjusted according to the size and shape of the profile to ensure uniform cooling.

Precision control of traction equipment

Matching traction speed and extrusion speed: The traction speed of the traction equipment should be accurately matched with the extrusion speed of the aluminum profile. If the traction speed is too fast, it will cause the aluminum profile to stretch and deform, resulting in longer and thinner dimensions; If the traction speed is too slow, the profiles will accumulate at the outlet of the extruder, affecting the dimensional accuracy. By using a synchronous control system to ensure the synchronization of traction speed and extrusion speed, the error is generally controlled within ± 0.5%.

The use of high-precision traction equipment: high-precision traction equipment is used, such as servo motor-driven traction machines. This type of tractor can accurately control the traction speed and traction force, and can make real-time adjustments based on feedback information from aluminum profiles. At the same time, the fixture of the traction equipment should be able to firmly clamp the aluminum profile without causing damage to the surface of the profile, to ensure the stability of the traction process and the accuracy of the profile size.

Author:

Mr. zhichengaluminumindustry

E-mail:

zcd.aluminum@gmail.com

Phone/WhatsApp:

+852 64053048