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No matter how good the quality of the finished parts, high qualitymetal surface finishingcan further improve its performance. In the manufacturing process of metal parts, the surface treatment is an indispensable link. Proper surface finishing not only beautifies the appearance of the metal parts, but also significantly extends their service life.
This paper will deeply analyze severalcommon surface treatment techniquesand their principles of action, aiming to help readers with a more comprehensive understanding of the essence of this field. Now, let's uncover the mystery of the surface finishing together!

How Does surface finishing Work？

Surface finishing is the process of modifyingor protecting the surface of a material through a series of process steps to improve the material's corrosion resistance, wear resistance, conductivity, aesthetics or other specific properties. The specific method ofsurface finishing varies depending on the materialand desired properties, but generally follows these basic steps:

1. Pre-cleaning:First, thematerial surfaceneeds to be thoroughly cleaned to remove grease, dirt, oxides and other impurities. This can be achieved by methods such as solvent cleaning, alkaline or acidic cleaning, electrochemical cleaning or ultrasonic cleaning.
2. Surface Preparation:Depending on the finishing needs, further preparation of the surface may be required, such as roughening to increase the bonding strength of the coating to the substrate, or activation/passivation to change thechemical properties of the surface.
3. Coating or Treatment Application:Applying the desired coating or specific  finishing to a clean and prepared surface. This may includeelectroplating, thermal spraying, electrocoating, spray painting, anodizing, electroless plating, etc. The choice of coating depends on the properties required, such as corrosion resistance, wear resistance, electrical conductivity or aesthetics.
4. Curing and Drying:After acoatingor finishing has been applied, curing and drying is usually required. This can be achieved through heat treatment (such as oven curing) or natural drying to ensure that the resin, curing agent and other components in the coating react chemically to form a strong coating and to remove moisture or solvents in the coating.
5. Inspection and Quality Control:Finally, the treated surface is inspected to ensure it meets predetermined performance requirements. This may include visual inspection, thickness measurement, adhesion testing, corrosion resistance testing, etc.

What Are the Most Common Surface Finishing Techniques?

The most common surface finishing technologies mainly include the following categories:

1. Mechanical surface finishing

Technology	Description
Grinding	Using grinding products to form lines on the surface of the workpiece or remove surface defects can achieve a decorative effect.
Polishing	Improve the gloss and flatness of the material surface to make it smoother.
Sandblasting	The process of cleaning and roughening the surface of a substrate by using the impact of high-speed sand flow, that is, using compressed air as power to form a high-speed jet beam to spray the spray material to the surface of the workpiece that needs to be treated at high speed, causing the appearance or shape of the workpiece surface to change.

2. Chemical surface finishing

Technology	Description
Electroplating	Depositing a layer of metal or alloy on a metal surface to increase the corrosion resistance and aesthetics of a product. Common electroplating types include zinc plating, chromium plating, nickel plating, etc.
Anodizing	Mainly used for surface finishing  of aluminum and its alloys to improve corrosion resistance by forming an oxide film.
Passivation	Cleaning the stainless steel surface with an acid solution to remove contaminants and promote the formation of a passive film on the newly created surface Passivation finishing mainly improves the corrosion resistance of stainless steel materials by dissolving all carbon steel contaminants, sulfide inclusions, etc. on the stainless steel surface.
Pickling	Use acidic substances to remove impurities on the surface of stainless steel materials (including high-temperature oxides generated by welding or heat treatment, etc.), and etch some corroded surfaces.

3. Coating finishing

• Powder coating: The powder coating is evenly attached to the surface of the workpiece through electrostatic spraying and other methods, and then solidified to form a coating.
• Spray painting: Use a spray gun tospraypaint on the surface of the workpiece to form a uniform coating.

4. Thermal finishing

• Heat finishing :such as quenching, tempering, etc., changes the internal structure of the material through the heating and cooling process, thereby improving the strength, toughness and durability of the material.
• Laser surface modification:Thelaser beamis used to rapidly heat and cool the workpiece surface, thereby changing the surface structure and improving the surface hardness, wear resistance and corrosion resistance.

How Does Surface Finishing Improve Product Performance?

Surface finishing  is a key process to improve product performance. Specific effects include:

1. Enhance corrosion resistance and wear resistance:Electroplating (such as chromium plating,zinc plating) forms a protective layer, and anodizing and passivation treatments form an isolation film, which all improve corrosion resistance and enhance wear resistance.
2. Improve electrical conductivity:Fine sand blasting cleans the surface to increase the contact area; electroplating gold, silver and other metals significantly improves the electrical conductivity of electronic components.
3. Provide decorative finishes:Spraying with colorful paint, electroplating metal texture, printing patterns and text, all of which enhance the aesthetics and added value of the product.
4. Reduce friction and enhance mechanical performance:Improve the material and roughness of the contact surface, use wear-resistant materials; apply lubricant to form an oil film, significantly reduce friction, and are widely used in the automotive and mechanical fields.

What Are the Challenges of Surface Finishing?

Surface finishing challengesinclude:

Technical aspects:

1. High-precision requirements:The development of manufacturing industry promotes the improvement of precision requirements, which requires advancedmachine tools, high-precision tool holders and stable environments.
2. New material processing:High-strength alloys,ceramics and other materialsare difficult to process and are prone to tool wear and surface cracks. New processing methods need to be explored.

Cost:

1. High equipment and process costs:covering purchase, maintenance and training, limiting the popularity of small and medium-sized enterprises.
2. Yield problem:There are many influencing factors, which lead to rising costs and affect competitiveness.

Talents:

1. Shortage of high-quality talents:deep professional knowledge, rich experience and rigorous attitude are required, and the training cycle is long, which restricts technological development.

Market Competition and Environment

1. Market competition is fierce:it is necessary to ensure quality while reducing costs and improving efficiency.
2. Energy consumption and pollution:High-speed and high-precision processing consumes a lot of energy, and green and sustainable development needs to be achieved.

How Is Surface Finishing Used in Different Industries?

Advancedsurface finishing technology has had a profound impact on multiple industriesby significantly improving product quality, efficiency and durability, as reflected in:

1.Automotive industry

In the process of pursuing both aesthetics and functionality,the automotive industry is highly dependent on advanced surface finishingtechnology. Whether it's the polishing of body panels or coating techniques used to enhance corrosion resistance, these finishing play a vital role in ensuring a vehicle's long-lasting durability and visual aesthetics.

2.Aerospace industry

In the aerospace industry, cutting-edge surface finishing technologies such asCNC grindingand laser texturing are widely used to produce high-reliability components. Not only are these components capable of operating reliably in extreme environments, they are also manufactured to extremely high levels of precision and tolerance.

3.Biomedical industry

The biomedical industry also benefits fromadvanced surface finishing technologies.By providing smooth and biocompatible surfaces for implants and medical devices, these technologies reduce the risk of infection and improve patient outcomes.

4.Consumer goods industry

In the field of consumer goods,advanced surface finishing technologies not only enhance the appearance appeal of products, but also significantly improve their durability. This makes consumer products more competitive in the market, while also extending the service life of products and satisfying consumers' pursuit of high-quality life.

5.Electronic manufacturing

Electronics manufacturers use advanced surface finishing technologiesto significantly improve the durability and overall performance of electronic devices. For example, in the manufacturing of consumer electronics such as smartphones and computers, key technologies such as grinding and coating are essential to create smooth and highly conductive surfaces.

 

What Are the Different Surface Finishing Standards & Symbols?

Surface Finishing Symbols

In manufacturing and engineering, understandingsurface finish symbolsand roughness parameters is critical. These parameters are the key language for evaluating surface quality, functionality and suitability. Commonly used parameters include:

1. Ra:average surface roughness, a basic evaluation parameter, represents the arithmetic mean of the absolute value of the surface profile height and reflects the average condition of the surface texture.Ra is critical for applications such as surface contact, wear and lubrication, and is typically measured in microinches (µin) or micrometers (µm). It is calculated by averaging the absolute values ​​of the vertical deviations from the mean line over the length of the surface sample.
2. Rmax: represents the vertical distance between the highest peak and the lowest valley on the surface, reflecting the limit of surface irregularity. It is crucial for tight sealing or smooth sliding surface applications. The unit is usually µin or µm. It is obtained by measuring the vertical distance between the highest peak and the lowest valley along the length of the sample.
3. Row:International standard parameter, to fully understand the surface texture, divide the roughness profile into five segments, measure the height difference (Rt) between the highest peak and the lowest valley in each segment and average it. It is very important for applications in high-precision engineering that require a detailed understanding of surface peaks and valleys. The unit is also µin or µm. When calculating, first measure the Rt of five segments along the evaluation length, and then find the average value Rz.

Surface Finishing Standards

Understanding and followingsurface finish standardsis critical to consistency and quality assurance in the manufacturing process. These standards provide clear guidelines for the measurement and classification of surface texture.

1.ISO (International Organization for Standardization) 1302 standards:

This series of standards covers methods for specifying, measuring and indicating surface finish. ISO standards are widely used worldwide and apply to a variety of materials andfinishing processes.They are critical to ensuring compatibility and high quality in global manufacturing.

2.ASTM (American Society for Testing and Materials) Y14.36M Standard:

ASTM provides a set of standards for the measurement andcharacterization of surface finish. These standards dominate U.S. manufacturing and provide a solid foundation for quality control, product specification development, and manufacturing process optimization.

Work with LS to improve your surface finishing quality

Surface finishing is of great significance in the machining processbecause it directly affects the quality and performance of machined parts. It helps achieve the required dimensional accuracy, smoothness and surface integrity. Proper surface finishing reduces friction, increases wear resistance and improves the functionality of machined parts. It also improves compatibility with other parts, facilitates assembly, and helps improve the overall aesthetics of the product and end-user satisfaction.

At LS Manufacturing, we offer a comprehensive range of surface finishing services designed to enhance the performance and aesthetics of your components.Our ISO 9001:2015 certified processincludes a variety of techniques includingpolishing, anodizing, powder coating and electroplating, allowing us to achieve superior surface quality and durability. These finishing processes not only improve the appearance of the part, but also improve wear, corrosion and environmental resistance. Whether you need a finish for a prototype or production part, our experienced team is dedicated to delivering a high-quality finish that meets your specific project requirements, ensuring functionality and visual appeal.

Summary

There are manytypes of surface finishing technologies, each with its own characteristics. In practical applications, it is necessary to select the appropriate surface treatment technology based on comprehensive considerations such as material type, product performance requirements, cost budget and other factors. With the advancement of science and technology and the development of industry, surface finishing technology is also constantly innovating and upgrading. In the future, more environmentally friendly, efficient and intelligent surface treatment technology will become a development trend. By in-depth understanding of the working principles and application scenarios of these technologies, we can better grasp the development trends and opportunities of modern industrial manufacturing.

Disclaimer

The content on this page is for reference only.LSdoes not make any express or implied representation or warranty as to the accuracy, completeness or validity of the information. No performance parameters, geometric tolerances, specific design features, material quality and type or workmanship should be inferred as to what a third party supplier or manufacturer will deliver through the Longsheng Network. It is the responsibility of the buyerseeking a quote for partsto determine the specific requirements for those parts.Pleasecontact usfor moreinformation.

LS Team

LS is an industry-leading companyspecializing in custom manufacturing solutions. With over 20 years of experience serving more than 5,000 clients, we focus on high-precisionCNC machining,sheet metal fabrication,3D printing,injection molding,metal stamping,and other one-stop manufacturing services.
Our factory is equipped with more than 100 advanced 5-axis machining centers and is ISO 9001:2015 certified. We provide fast, efficient, and high-quality manufacturing solutions to customers in over 150 countries worldwide. Whether it’s low-volume production or large-scale customization, we can meet your needs with delivery as fast as 24 hours. ChoosingLS Technologymeans choosing efficiency, quality, and professionalism.
To learn more, please visit our website:www.lsrpf.com

FAQs

1.What is the surface finishing process?
Surface finishing  process is a series of processes that change the surface properties of materials through physical, chemical or mechanical methods. These processes are designed to improve the material's appearance, improve corrosion resistance, enhance hardness, change the coefficient of friction or achieve other specific performance requirements. Common surface finishing processes include spraying, electroplating, anodizing, thermal spraying, laser processing, etc.

2.How is surface finish obtained?
Surface finish is usually achieved by methods such as machining, polishing, grinding or chemical etching. Mechanical processing such as milling and turning can initially form a smoother surface; polishing uses polishing agent to rub on the material surface to remove tiny scratches and unevenness; grinding uses grinding tools and abrasives to smooth the surface more finely; chemical etching uses chemical reactions to remove part of the material surface to achieve a smooth effect.

3.What is the process of completion?

The surface finishing process usually includes three stages: pretreatment, surface finishing and post-treatment. The pretreatment stage is mainly to clean and prepare the material surface, and remove impurities such as oil, dust, and oxide layers; the surface treatment stage is to select an appropriate process to treat the material surface according to specific needs; the post-treatment stage is to perform necessary curing, drying, inspection or further processing on the treated surface to ensure that the performance and appearance of the coating or plating meet the requirements.

4.Why use surface finishing ?
There are many reasons for using surface finishing , which mainly include the following aspects: first, to improve the appearance of the material and increase the aesthetics and market value of the product; second, to improve the corrosion resistance of the material and extend its service life; third, to enhance the hardness, wear resistance and scratch resistance of the material; fourth, to change the friction coefficient of the material to adapt to specific application scenarios; fifth, to meet specific performance requirements, such as electrical conductivity, thermal conductivity, lubricity or anti-reflection, etc. In addition, surface finishing  can also be used for identification, anti-counterfeiting or other specific functions.

Resource

1.Surface finishing

2.Polishing

3.Honing (metalworking)