Surface Quality – This is an aspect of designing aluminum extrusions that have received less attention than it should. This problem usually only arises after the prototype of the new aluminum profile has been machined. Often it is too late to act.
Before we use the profile bending machine to bend the aluminum profile, there is a necessary inspection: check whether the surface of the aluminum profile is normal and free of damage and foreign objects. Ensure the finished product rate of the workpiece and not damage the aluminum bending machine.
So what are the reasons for the surface damage of aluminum profiles?
5 reasons for the surface damage of aluminum profiles
- There are impurities attached to the surface of the aluminum ingot or the composition of the aluminum ingot is segregated. When there are a large number of segregated floating substances on the aluminum surface and the aluminum ingot has not been homogenized or the homogenization effect is not good, there are a certain number of hard metal particles in the aluminum ingot. When the aluminum flows through the working belt during the extrusion process, These segregation floats or hard metal particles adhere to the surface of the aluminum working belt or cause damage to the working belt, and eventually cause scratches to the surface of the aluminum profile;
- There are sundries in the mold cavity or working belt, and the hardness of the working belt of the mold is low so that the surface of the working belt is injured during extrusion and scratches the aluminum profile;
- There is bare metal on the discharge track or the pendulum bed or there are hard inclusions in the graphite strip, which will scratch the surface of the aluminum profile when it comes into contact with the aluminum profile;
- When the fork rod sends the profile from the discharge track to the swing bed, the aluminum profile is bruised due to excessive speed;
- Artificially dragging the aluminum profile to cause scratches;
- In the process of transportation, the aluminum profiles are rubbed against each other or squeezed to cause damage
5 measures to solve the surface damage of aluminum profiles
- Strengthen the quality control of aluminum ingots;
- Improve the quality of mold repair, regularly nitriding the mold and strictly implementing the nitriding process;
- Use soft felt to isolate the aluminum profile from the auxiliary device to minimize the contact damage between the aluminum profile and the auxiliary device;
- Handle with care during production, and try to avoid random dragging or flipping of aluminum profiles;
- Arrange the aluminum profiles reasonably in the material frame to avoid mutual friction as much as possible.
Avoid surface damage starting from the design of aluminum profiles
When aluminum profiles come out of the extrusion press, they have to be placed on the run-out table on a certain side. Since the profile is still soft when it comes into contact with the table, therefore, when it comes into contact with the table, the latter may inevitably generate traces, for example, in the form of small dents.
The cross-sectional profile may also have an impact on the quality of its surface. The large difference in thickness of the walls or the joints of the walls and shelves can lead to an inhomogeneous structure of the metal surface. A big difference in wall thickness, for instance, could lead to visual anomalies with anodizing, and with powder coating, tangible marks could result.
Designing a slightly larger radius in the profile will make the aluminum flow smoothly during the extrusion process. This will result in fewer structural differences in the walls of the profile.
Decorative ornamental ribs or corrugations can also help prevent the broad surfaces in the profile from being damaged. If there are differences in the structure of the metal left, we will not see them anymore.
Avoid corrosion of aluminum profiles during packaging and handling
At the manufacturer profiles, which must be subjected to one or another surface treatment, may become dirty before this treatment. This could take the form of oil or grease, but also fingerprints, which etch the profile with natural acids. These fingerprints are still visible after anodizing. The occurrence of this defect on the surface of the profiles is prevented by the use of clean gloves during all manual work with the profiles.
Keeping the aluminum profiles in stock for lengthy periods of time may also affect surface quality after anodizing. This is a consequence of the natural corrosion process. Pre-treatments can help solve this problem.
Too long storage profiles in stacks and stacks can also impair the quality of their surface. This is due to the natural corrosion processes.
And while you think about how you handle the products while packing, you need to consider the method of packing, too. Think hard about the materials you use for packing, and the condition of these materials You need to think through in advance not only a way of packaging but also materials, which in this case will be applied. for instance, some cardboard and paper materials have acidic properties and, when wet, can leave noticeable traces of acid corrosion on the profiles.
Classes of surface quality
class 1 – Highest requirements
- It applies to items of household appliances, lighting devices, decorative items, etc.. P.
- Maximum delivery length: 2,4 m, if not agreed on other lengths.
- class 1 It can be achieved only with special profiles of anodized pretreatment – chemical or mechanical. Such a mechanical surface treatment typically includes grinding, Processing of metal brushes, and polishing.
- profiles, in which the surface on all sides is visible, can be handled by this class only if the profile is subjected to grinding on all sides.
- During transport, each profile must be separately protected from damage.
- Each profile requires individual handling and visual inspection, which entails an increase in labor costs.
- alloys only 6060, 6063, and 6463.
- Evaluation of surface quality is produced at a distance of 0,6 m for 5-10 seconds.
class 2 – Very high demands
- It applies to items of furniture, parts of household appliances, picture frames, etc.. P.
- Maximum delivery length: 2,4 m, if not agreed on other lengths.
- The highest class for brilliant anodizing, including, additional machining. Brilliant anodizing manifests and amplifies all surface defects.
- profiles, in which all sides are visible, usually are not produced on the surface quality of this class.
- this class, is usually, applied to the anodized profiles.
- During transport, each profile must be separately protected from damage.
- Each profile requires individual handling and visual inspection, which entails an increase in labor costs.
- alloys only 6060, 6063, and 6463.
- Evaluation of surface quality is produced at a distance of 1 m for 5-10 seconds.
class 3 – High requirements
- It applies to furniture parts, lighting equipment, refrigerators, shower cabin, and Decorative Item’s interior.
- Usually applied to the anodized profiles.
- profiles, in which all sides are visible, usually are not produced on the surface quality of this class.
- alloys only 6060, 6063, and 6463.
- Evaluation of surface quality is produced at a distance of 2 m for 5-10 seconds.
class 4 – The normal requirements
- It is applied to building systems, facades, windows, doors, and handrails, as well as products for public buildings, for example, furniture, exhibition stands, and shower cabins.
- It is applied to the painted and anodized profiles.
- alloys only 6060, 6063, and 6463.
- Evaluation of surface quality is produced at a distance of 3 m for 5-10 seconds.
class 5 – Low requirements
- It is used for building systems, balconies, roofs, windows, doors, openings, railings, sailing masts, stairways, football goals, and skladnblh walls.
- standard profiles, for example, angles, and channels.
- alloys 6060, 6063, 6463, 6005A, 6082, 6101.
- Evaluation of surface quality is produced at a distance of 5 m for 5-10 seconds.
class 6 – No requirement
- It is used for carrying constructional profiles, Railings, forests, falsework, and sliding partitions.
- standard profiles, including alloys of sredneprochnyh, such as 6082. construction profiles, for example, truck bodies.
- profiles, which are not specified visible surfaces.
- Profiles of aluminum brand 1050A can be pressed only on the surface quality class.
Works Cited: Aluminum surface quality – Aluminium Guide How design can influence surface quality