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Process Analysis — Brushed Sheet Metal
2025-10-10
Sheet metal processing is a technical endeavor. To produce high-quality pieces you need not only excellent technique but also high-precision equipment. Among the many sheet metal processes, brushing (creating a brushed finish) is one of the most common and widely used. It gives the metal surface uniform grain lines that are both attractive and practical. So how is brushed sheet metal made, and what should you pay attention to? Below, I’ll explain it in a clear and easy-to-understand way..
1. What is sheet metal brushing?
Brushing is a surface treatment process that uses abrasive belts to grind the surface of metal parts. Its main purposes are:
(1).To remove surface defects such as scratches, pits, or oxidation marks;
(2).To form a decorative surface with uniform texture and controlled roughness;
(3).To enhance the visual and tactile quality of the finished product.
The brushed metal surface not only looks more textured, but can also cover up minor surface flaws to a certain extent.
2. Preparation before brushing
(1). Sample confirmation
Before brushing, a standard sample must be prepared, which can be signed by the customer or made according to the customer's requirements. This sample is the basis for testing the brushing effect and is very important.
(2). Security Check
Operators must wear labor protection equipment (such as gloves, goggles, etc.) to ensure safety.
(3). Equipment Inspection
Before starting the machine, make sure all systems of the equipment are normal, including whether the sanding belt is firmly installed and whether the equipment is running smoothly.
(4). Workpiece inspection
Check whether the workpiece is flat, especially the mesh plate or thin plate. If there is any deformation, it needs to be returned to the previous process for leveling.
Check whether there is a protective film or glue stain on the surface. If there is, it must be removed thoroughly, otherwise it will affect the brushing effect.
3. Detailed Brushing Procedure
(1). Rough brushing (preliminary grinding)
Use an used 180# sanding belt (the texture of the new sanding belt is too coarse and not suitable for direct use).
During operation, hold the pressure plate with one hand and press it on the abrasive belt to make the abrasive belt evenly contact the workpiece; use the other hand to push the platform fixed plate to swing back and forth.
Repeat the operation several times until the surface of the workpiece has clear lines, no pits, no burns, etc.
⚠️ Note: Do not pull too deep or use too much force at one time, otherwise it will easily cause the surface to burn.
(2). Dealing with burnt issues
If there is a burn phenomenon during the brushing process, you can rub some black oil sticks or a small amount of diesel on the surface of the sanding belt, and then gently brush it again until the burn mark disappears.
(3). Dealing with uneven surfaces
If the workpiece is slightly uneven locally, you can use a pressing plate or your fingers to apply local pressure to perform rough pulling and preliminary leveling.
(4). Fine brushing (fine grinding)
After the rough brushing is completed, use 400# high-grade fine sand belt for fine finishing.
The method is the same as for rough pulling, but it should be gentler and more even.
The surface after fine brushing should be free of scratches, bumps and pollution, and the construction surface and the transition surface should be naturally connected, and the transition line should be straight.
(5). Grain direction consistency
The brushed lines must be uniform and in the same direction — no skipped areas. Scratches or pits that run perpendicular to the grain must be completely removed.
(6). Handling of small workpieces
For smaller workpieces, a jig (special fixture) should be used to fix them to ensure that the parallelism error between the upper and lower surfaces is less than 0.1mm.
4. Quality Inspection and Subsequent Processing
(1). Inspection against sample
After the brushing is completed, it is necessary to check it against the sample, and the surface texture must be uniform and consistent without obvious defects.
(2). Thickness control
The thickness of the brushing layer should be less than 0.1mm. Excessive grinding will affect the strength and dimensional accuracy of the workpiece.
(3). Packaging and storage
Qualified workpieces should be separated by white EPE (pearl cotton) and placed on general pallets or special equipment to prevent the surface from being scratched or contaminated.
5. Common Problems and Solutions
(1). Burnt surface
Cause: Excessive pressure or too thick abrasive belt.
Solution: Reduce pressure, use an old sanding belt or rub with black oil stick/diesel.
(2). Uneven texture
Cause: Unstable operation technique or uneven wear of the abrasive belt.
Solution: Maintain uniform force and replace the sanding belt regularly.
(3). Missing pull or scratches not removed
Cause: Inattentive inspection or negligent operation.
Solution: Check the surface carefully before brushing and check it against the sample after brushing.
While sheet metal brushing may seem simple, it actually requires patience and skill. From preparation to rough brushing, fine brushing and final inspection, every step must be meticulous. Only by strictly following the process requirements can a brushed product with uniform grain and high-quality texture be produced.