Surface finishing is a crucial final step in the metal parts manufacturing process such as CNC metal machining and sheet metal fabrication, this is because it significantly impacts both the appearance and functionality of metals. Among the various surface finishes available, brushing finish creates a uniform surface, enhancing the cleanliness and consistency of otherwise uneven metal surfaces. You may be wondering what brushing finish is and how it works. This article will explore the brushing process, the tools involved, the different types of brushed metals, their applications, and how brushing compares to other common metal finishes.
What is a Brushing finish?
A brushing finish is a texturing technique applied primarily to metal surfaces. It involves a surface treatment method that uses abrasive material to form lines on the surface of metal parts to achieve a distinctive textured appearance. Brushing treatment can give the metal surface a non-mirror metallic luster, which has a very strong decorative effect like silk satin. It is becoming more and more popular in our daily lives.
Types of brushed finish patterns
Straight-grain brushed finish.
Straight grain Brushed finish uses mechanical friction to process straight lines on the surface of the metal sheet. It can brush away scratches on the surface of metal sheets and decorate the surface of metal sheets. There are two types of straight-grain brushing patterns: continuous silk pattern and intermittent silk pattern.
Continuous silk pattern
A continuous silk pattern is obtained by continuously rubbing horizontally and linearly on the surface of a metal sheet with a stainless steel brush.
Intermittent silk pattern
Intermittent silk pattern is processed on brushing machines. The metal sheet passes through the two sets of rollers to get brushed.
Thread brushed finish
The thread-brushed finish process uses a small motor with a circular felt on the shaft and the rotation of the felt to create thread patterns of consistent width on the surface of the metal sheet.
Corrugated brushed finish
Corrugated brushed finishes are generally made on a brushing machine or a graining machine. The axial movement of the upper set of grinding rollers is used to grind the surface of the metal sheet to obtain a wavy pattern.
Random brushed finish
A random brushed finish is an irregular, matte silk pattern without obvious lines obtained by rubbing the metal sheet back and forth, left and right under a high-speed running copper wire brush. This kind of processing has high requirements on the surface of the metal sheet.
Spin brushed finish
The Spin brushed finish is a silk pattern obtained by rotating and polishing the surface of a metal sheet by using a cylindrical felt or a grinding nylon wheel mounted on a drilling machine and mixing the polishing paste with kerosene. It is mostly used for the decorative processing of circular signs and small decorative dials.
What material can be brushed?
The brushing finish process is often used for metal parts such as stainless steel, Aluminum, and copper. Stainless steel 304, 316, 312, and Aluminum alloys are the most commonly used metal materials for brushing finish. Plastic and rubber materials can also be used for this process.
Standard Brushes For Brushing Finish
Two major brushes are widely used in the brushing finish process to manufacture metal parts, especially in the CNC metal machining industry.
Steel Wire Brushes
Steel wire brushes are popular because they do not change metal parts’ dimensions. It can create different types of brushed finish patterns on the metal part surface. The wire tips of these brushes are made of steel and won’t clog up with debris during use.
Power Brushes
Power Brushes are made of ferrous and non-ferrous wires, carbon steel, and natural and synthetic fibers. They are widely used in brushing finish operations. Manufacturers choose different types of power brushes according to the metal surface, condition, filament filling, and trim length.
How To Brush A Metal Surface step by step
Step 1: Prepare the Surface
Clean and sand the metal to remove coatings, rust, and imperfections. This ensures a smooth, even base for the finish.
Step 2: Apply the Finish
Use an abrasive bristle brush to create fine lines by brushing in one direction. Choose the appropriate brush based on the metal type.
Step 3: Cure and Dry
Apply a protective coating, like oil or clear lacquer, to safeguard the brushed finish from damage.
Step 4: Inspect the Finish
Check the brushed surface for uniformity and quality. Once satisfied, the metal is ready for use or further processing.
Tips for brushing process
- The brushing finish machine’s processing range is generally no greater than 1000mm, and the applicable minimum metal thickness is 0.5mm.
- The brushed surface of the workpiece cannot have any convex parts, otherwise, the convex parts will be flattened.
- A brushing finish should be done before other treatments like electroplating because it will break this treatment.
- It is better to control the grinding amount within 0.05 – 0.1mm on one side.
Advantages of brushing finish
Improve part durability
the brushing finish can protect the metal parts’ surface against wear and tear which could be caused by handling and transportation. It also could make the surface of metal parts more corrosion-resistant which improves metal parts’ durability.
Enhances part aesthetic
The main reason people want brushing finished parts is they have a great textured appearance which looks special when compared with other parts. Meanwhile, brushing finish helps to hide scratches, dents, and marks of machined metal parts.
Disadvantage of brushing finish
Brushing finish process will cause material loss with a rate ranging from 10% and 15%, which will lead to an increase in material costs and reduce production efficiency.
The brushing finished surface quality is not stable because it is affected by too many factors during the operations, crack and deformation may happen.
Common Applications of Brushing Finish
Home decoration
The brushing finish process can be used in various home decorations such as door handles, handles, wall cabinets, etc. The brushing finish can make the parts look more elegant.
Electronic product
In the manufacturing of electronic products, the brushing finish process is also often used. For example, products such as mobile phone cases and laptop cases use brushing finish technology to increase the aesthetic of the product.
Automotive components
The brushing finish process is also widely used In automobile parts. For example, car wheels, door handles, windshield frames, and other products all use brushing finish technology to achieve texture effects.
Conclusion
Choosing the right finish for a machined part is as important as the machining process itself. The finish not only enhances the part’s appearance but also increases its durability. Therefore, selecting the best finish is a critical decision. To ensure your part’s finish is handled perfectly, you may need to seek advice from professionals in the machining field. KUSLA is a company that can assist with all your finishing needs. Contact us today!
FAQ
What is the difference between a brushed finish and a satin finish?
The satin finish and the brush finish are not shiny. The satin finish is smooth but the brush finish looks textured by the wire brush.
How to brush stainless steel parts manually?
Use sandpaper with a grit of 180 to 240 and scrub your stainless-steel parts toward the grain, using even pressure and scrubbing several times. Then shift to a finer grit of 320 to 400 to remove any remaining scratches or marks.
