3 Injection Molding Surface Finish Standards for Good Injection Molded Parts

Injection molding is a manufacturing process that allows for the mass production of identical parts from various plastics. Achieving precise injection molding surface finish standards in the product requires strict adherence to the production line. Understanding injection molding surface finish standards is key to producing quality parts with repeatable results. Through this article, I will provide detailed insight into the requirements and specifications of injection molding surface finish standards. Besides, You will also know how to properly measure and assess these finishes.

Why Should You Need to Maintain Injection Molding Surface Finish Standards?

Injection Molding is an important process that has a major impact on the quality of products. Having high injection molding surface finish standards is essential for producing quality parts and components. It is an essential tool in the fabrication of plastic parts and products, and it relies on strict adherence to surface finish standards in order to achieve the desired level of quality. Maintaining these standards is critical for ensuring that injection molded parts meet their design requirements, as well as applicable industry regulations.

Tools You Can Use to Maintain Injection Molding Surface Finish Standard

Injection molding is a popular manufacturing process used to produce high-quality machining products. One of the essential aspects of ensuring that the final product meets industry standards is maintaining injection molding surface finish standards. This can be achieved by using specific tools and techniques designed to enhance surface finish performance.

Mold Temperature Control Units (TCUs):

These devices regulate mold temperatures during injection molding, which helps reduce cycle times and improve surface finishes. They allow manufacturers to maintain consistent temperatures throughout the entire process, resulting in better-quality products with improved aesthetics.

Ultrasonic Cleaning Machine:

This machine uses high-frequency sound waves to generate tiny bubbles in a cleaning solution that cleans the surfaces of the injection molds without causing damage. Ultrasonic cleaning machines are effective at removing dirt, debris, and other contaminants from mold surfaces that can negatively impact surface finish quality.

Mold Maintenance:

It’s important to keep molds clean and free of debris to prevent defects in the final product. Regular cleaning with an appropriate solvent or detergent can help remove any buildup or contaminants on the mold surface. Additionally, proper storage and handling of molds when they are not in use can help prevent damage or wear that may affect the surface finish.

Polishing Equipment:

Polishing machines are designed to remove any imperfections or rough surfaces from molded parts, creating a smooth and uniform appearance.

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4 Types of SPI Injection Surface Finishes You May Use

Gloss Finish (Grade A):


When it comes to injection molding, surface finish is one of the most critical factors that affect product success. Gloss Finish is a popular and highly sought-after injection molding finish that provides outstanding quality and durability. This finishing technique involves using diamond polishing tools to create an ultra-smooth, glossy finish on the molded part.


  • Excellent resistance to wear and tear.
  • Resists scratches, chips, and other types of damage caused by regular use or handling. Provides superior clarity and enhances the appearance of parts.


  • The Gloss Finish (Grade A) is also well-known for its ability to resist staining caused by exposure to dirt and grease.

Standard Chart:

Semi-Gloss Finish (Grade B):


Semi-gloss finish is one of the most popular injection molding spi surface finishes available in the market. It is a grade B surface finish that provides a smooth and glossy appearance to the product. This surface finish is achieved by using the SPI (Society of Plastics Industry) standard polishing process, which involves using fine abrasive materials to remove any imperfections on the mold surface.


  • Especially useful for products that require a shiny and elegant look such as automotive parts, consumer electronics, toys, and household appliances.
  • Provides an excellent balance between glossiness and texture.
  • Have some functional benefits.


  • It may require frequent cleaning and polishing in order to retain its shine.
  • Scratches and scuffs can be shown more easily than other finishes.

Standard Chart:

Matte Finish (Grade C):


Matte Finish is an excellent option for creating a soft and textured surface. This type of finish is achieved by using a special tool that creates tiny pits or depressions on the surface of the molded part. The result is a non-glossy, diffused reflection that gives the product a high-quality look and feel.


  • Can effectively hide any imperfections or defects on the molded part’s surface.
  • Adds an extra layer of durability and resistance to scratches and other signs of wear and tear.
  • It provides better grip and texture to the part.


  • It can make parts appear dull or washed out.
  • Tend to show fingerprints and smudges more easily than glossy finishes.
  • Have a rougher surface texture compared to other finishes like gloss or satin.

Standard Chart:

Textured Finish (Grade D):


Textured Finish (Grade D) is one such injection molding surface finish that has been gaining a lot of popularity in recent times.


  • Ability to hide imperfections on the surface.
  • It can provide a better grip or tactile feel.
  • Provides increased surface area and rigidity.


The drawback is that a textured finish can make cleaning and maintenance more difficult. The roughness and unevenness created by the texture can trap dirt and debris, requiring more effort to clean thoroughly.

Standard Chart:

VDI Injection Textured Finishes Standard Chart

There are several VDI finishes available for injection molding that can help achieve different aesthetic and functional goals.

Mold Tech Injection Molding Surface Finishes Standard Chart

The mold tech injection surface finish has three categories.

Standard Chart of Mold Tech-A:

Standard Chart of Mold Tech-B:

Standard Chart of Mold Tech-C

Issues You Must Have in Your Mind to Choose Injection Molding Surface Finish

When looking for an injection molding surface finish, there are several factors that you need to consider to ensure that you achieve your desired results.

  • You need to consider the purpose of your product and its end-use environment. The type of surface finish that you choose will determine how well your product can withstand wear and tear or exposure to different environments.
  • You need to consider the aesthetic appeal of your product. Do you want a matte or glossy finish? Should it have texture or pattern on its surface? These factors can significantly affect the final look and feel of your product and influence customer perception.
  • The design of your product should also influence your choice of injection molding surface finish. If your product has intricate details or complex shapes, then a smooth surface finish would be ideal since it enhances the aesthetic value and texture.
  • When choosing an injection molding surface finish, you need to consider the type of material used in making your product.


Understanding the right injection molding surface finish standards and applying the right finishes are essential to ensure a quality product and satisfied customers. The correct surface finish can be chosen to meet the needs of almost any application. To get the best results, it’s important to consider all of the factors involved in selecting an appropriate surface finish, such as cost, aesthetics, durability, and functionality. By taking a close look at materials and production processes, companies can select an injection molding surface finish that meets their requirements.