Surface finish on CNC plastic parts advice, Manufacture tool, Computer numerical control tips, Gantry systems guide

The Surface Finish on CNC Plastic Parts

26 September 2022

Surface finish improves a surface layer with unique properties using a chemical or a product. It can use to resist rust, increase the aesthetic appearance and enhance the strength and firmness of CNC machined plastic parts.

Surface finishing of CNC plastic parts plays a vital role in the part’s performance. It changes the physical appearance of the parts by making their surface either smooth or rough. A smooth surface gives an attractive appearance. On the other hand, a rough surface makes a part dull and unattractive.

Moreover, a better surface finish protects the plastic parts from the wear and corrosion resulting from dust and environmental effects. As a result, it makes the parts wear and corrosion resistant.

Reasons for the Poor Surface Finish on CNC Plastic Parts

Poor surface finish can disturb the manufacturing process by creating problems and increasing the cost of the manufacturing process. Moreover, it also affects the quality and life cycle of the product resulting in a shorter life cycle for the products.

Before coming to a solution, it is compulsory to understand the primary reasons behind the poor surface finishing of CNC plastic parts. Here are some reasons that cause the poor surface finishing of CNC plastic parts.

1: Wrong Selection of Tool and Material

The resulting surface finish of a machined plastic part depends significantly on the quality of the material and tools. You must be careful while selecting the plastic material and tools. High-quality plastic materials and sharp tools show better surface finishing than low-quality plastic materials and tools.

2: Incorrect Part Design

Correct part design is essential to get CNC plastic parts’ desired and perfect finish. It requires a prototype for your mold or a blueprint of your required mold, but even if you have all these things, there are lots of chances of incorrect part designing if you don’t know how to optimize your design. Mold design must produce correctly to avoid any mistakes in part designing because its best production level makes it possible to get consistency and quality for your production.

3: Inadequate Post-Processing

Poor surface quality and other drawbacks can cause due to inadequate post-processing. It is the last phase in the additive manufacturing of CNC plastic parts where surface quality is improved and alignment of parts set according to the design specification.

Machinists use precision machining to fabricate exact cuts, holes, and flat or smooth surfaces. The post-processing step enhances a part’s aesthetics and eliminates its drawbacks and flaws.

4: Improper Manufacturing Processes

Properties of plastic materials and tools used in CNC machining can classify which process you can use. To achieve a shiny and smooth surface finish, you can choose lots of media such as glass beads, aluminum oxide, and sand.

Many other factors also determine the surface finish and manufacturing process of CNC plastic parts. Some elements are also responsible for improper manufacturing processes, such as cutting tool material, type of plastic, and machining condition. So make sure to optimize all these factors for the proper manufacturing process.

Tips to Get a Perfect Finish on CNC Plastic Parts

The surface finish directly affects the performance and durability of CNC machining plastic parts. Therefore, it is necessary to attain a perfect surface finish. Understanding the functions and performance of tools and material is essential if you want to start your business and look for prototyping services in your area. Professional prototyping services ensure the perfect finish and sound quality of CNC machining parts.

The following tips can help you to achieve a smoother surface finish of CNC plastic parts.

1: Choose the Right Tool for Geometry

The right cutting tool makes CNC operations so accurate, precise, and versatile and plays a vital role in machine accuracy. A smooth surface finish achieves using a sharp tool. The use of tools aggressively results in a poor quality finish.

You should choose the right tool for geometry, no matter how powerful the machining equipment you are applying. The wrong selection of tools will result in undesired machined parts manufacturing.

To attain a perfectly smooth finish, you must use a cutting tool with a suitable geometry. It allows the proper cutting of the material by tool resulting in a smooth surface finish. Some parameters for tool geometry are as follows:

End relief angle & side relief angle
Back rake angle & side rake angle

End cutting edge angle
Side cutting edge angle
Nose radius

2: Ensure an Accurate Feed Rate and Cutting Speed

Appropriate cutting speed is essential to get the best CNC machining plastic parts. To achieve this speed, you need to consider some factors such as:

How much do the tool and machinery cost, and what will be the tool’s expected life?

What cutting tool material is used, and how much is its strength and speed also important to consider in the CNC machining process?
To determine the cutting speed, the hardness of the material is also one of the main factors.

You must set the feed and speed rate accurately. It may vary for various materials. Use appropriate machine rates according to your cutting equipment to extend tool life. Otherwise, the tool may chatter, causing a rough surface finish.

3: Apply the Chemical Finishing Process

A surface finish uses to remove the manufacturing flaws, and it also improves the appearance of the final part. It also increases strength resistance and provides additional strength to CNC machined parts. The chemical finishing process thickens CNC plastic parts, making them more durable and non-conductive.

Chemical finishing uses for internal cavities, small parts, and high-performance engineering applications. It is more costly compared to other methods.

The chemical polishing process helps admirably in getting a smooth surface finish. The method performs by applying a chemical to the surface of the part. Then smooth polishing is done using a polishing wheel.

What Types of Finishes are appropriate for CNC Plastic Machining?

Surface finish is the most critical process in machining, giving a smooth, flawless look to CNC plastic parts. The finish hides scratches and other damages caused by cutting tools. Some post-processing methods can use to make perfect finished CNC plastic parts. Knowing the proper finishing and its correct applications is essential to creating a smoother surface.

1. Bead Blasting

Bead blasting is a surface finish process in which high-pressure steel or glass beads are directly shooted at high pressure on the surface of the CNC machined parts. It not only cleans the surface of the parts but also improves the surface appearance and creates a smooth surface with a dull texture. It also makes the component more durable by increasing its hardness.

But, the bead blasting process can damage your plastic parts during machining due to greater destructive force. You can choose to brush for your project for a matte appearance and textured look.

2. Brushing

Brushing can help to protect surfaces from damage and scratches and gives an attractive look. It adds elegance and superiority and uses for various applications such as:

Edge Blending
On Roughened Surface
For Cleaning Purpose

For Deburring

In the brushing process, the surface quality of the machined plastic parts improves to get a desired smooth appearance by using different types of brushes. The brushes have filamentary nature and differ significantly from the other coated products. They do not cause any scratches and damage to the plastic material. The brushing process can even create a smooth finish for complicated geometries.

Surface finish on CNC plastic parts Conclusion

Surface finish is the best option to maintain the original dimension and improve CNC plastic parts’ aesthetic appearance. Some common issues in the CNC manufacturing process are poor maintenance and the wrong selection of tools, materials, and service providers. Consult an expert and qualified CNC manufacturer to make the right choice for your upcoming projects.

At Waken Rapid Manufacturing, you will find well-versed experts to help you in choosing the best finish for your CNC machining parts. We ensure our customers get a smooth finish and close tolerance of CNC parts.

Reach out and connect with Waken Rapid Manufacturing for outsourcing to get high-quality CNC plastic machined parts for all your need.

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