PC（Polycarbonate）

The Ultimate Guide to Polycarbonate Machining: Tips, Advantages, and Disadvantages

About Polycarbonate

Polycarbonate (PC) is a highly versatile engineering thermoplastic material that is widely used in various industries due to its exceptional mechanical, thermal, and optical properties. It is a transparent and amorphous polymer that exhibits excellent impact resistance, high tensile strength, and good dimensional stability.

PC is commonly used in the manufacturing of parts and components for applications that require high transparency, such as automotive parts, medical devices, electronic housings, and safety glasses. It is also used in applications that require high impact resistance, such as bulletproof windows and machine guards.

One of the main advantages of PC is its ability to be easily machined with CNC processes, making it an ideal material for creating complex parts with high precision and accuracy. It can also be easily welded, bonded, and polished, which further enhances its versatility and usefulness in various applications.

Overall, PC is a highly desirable plastic material for CNC machining due to its exceptional properties and ease of machinability, making it a popular choice in many industries.Regenerate response

Subtypes

Generic PC (Polycarbonate)

CNC machining of polycarbonate is very popular. Its outstanding impact resistance makes it a great material for structural components. Polycarbonate has a nearly twice the impact strength as ABS and one of the strongest impact strengths among all engineering plastics. It can be easily formed without cracking and breaking.

Surface Finishes

There are two common surface finishes available for PC: vapor polishing and scratch-resistant coating.

Vapor polishing is an effective method for removing tool marks and blemishes from CNC-machined polycarbonate. This process involves exposing the surface of the polycarbonate to a solvent that causes the top layer to melt and flow, resulting in a smooth and polished surface. Vapor polishing is particularly useful for applications that require clear optical components, as it enhances the material’s transparency and clarity.

On the other hand, polycarbonate has a tendency to scratch easily, which is one of its disadvantages. However, there are coatings available that can preserve the optical clarity of the polycarbonate while improving its scratch resistance. These scratch-resistant coatings are applied to the surface of the polycarbonate and create a protective layer that can withstand wear and tear, making the material more durable and long-lasting.

In summary, both vapor polishing and scratch-resistant coating are valuable options for enhancing the surface finish of CNC-machined polycarbonate components, depending on the specific requirements of the application.

Design Tips

Consider wall thickness: Polycarbonate is a relatively flexible material compared to metals, so it’s essential to consider wall thickness when designing PC parts. Thicker walls can provide more strength and rigidity, but they can also lead to warping or cracking if the material cools too quickly during the machining process. Therefore, it’s crucial to balance strength with material flow and cooling times when designing PC parts.
Avoid sharp corners and edges: Polycarbonate has low impact strength at sharp corners and edges, which can lead to cracking or breakage. To avoid this issue, it’s recommended to use rounded edges and corners, especially for parts that will be subjected to impact or stress.
Minimize undercuts: Undercuts are features that are difficult to machine using CNC, as the tool may not be able to access the area. Minimizing undercuts can help to ensure that the part can be accurately and efficiently machined, reducing the risk of errors or damage.
Consider draft angles: Adding draft angles to the design can help to ensure that the part can be easily removed from the mold after machining, reducing the risk of damage and distortion.
Account for shrinkage: Polycarbonate has a relatively high shrinkage rate during cooling, which can lead to distortion or warping in the final product. To minimize these issues, it’s recommended to account for shrinkage in the design phase and adjust the dimensions accordingly.

FAQ

Is polycarbonate machinable?

Yes, polycarbonate is a machinable material that can be easily machined using CNC (Computer Numerical Control) milling or turning processes. Due to its amorphous structure, polycarbonate is known for its excellent dimensional stability, making it an ideal material for CNC machining.

What are the disadvantages of polycarbonate?

Despite its many advantages, polycarbonate also has some disadvantages. These include low scratch resistance, tendency to yellow over time when exposed to sunlight, and relatively low impact strength at sharp corners and edges. Additionally, polycarbonate is sensitive to some chemicals and solvents, which can cause it to crack or warp.

What is the lifespan of polycarbonate?

The lifespan of polycarbonate varies depending on the specific application and environmental conditions. In general, polycarbonate has a long lifespan and can last for several years with proper maintenance and care.

Does polycarbonate degrade over time?

Polycarbonate is a stable material that does not degrade over time under normal conditions. However, exposure to UV radiation or high temperatures can cause polycarbonate to degrade, leading to a decrease in its mechanical properties and yellowing.

Does polycarbonate yellow over time?

Yes, polycarbonate has a tendency to yellow over time when exposed to sunlight or other sources of UV radiation. This is due to the breakdown of the material’s molecular structure, which can cause a decrease in transparency and clarity.

At what temperature does polycarbonate become brittle?

Polycarbonate begins to lose its impact strength and become brittle at temperatures below -40°C (-40°F). Therefore, it’s important to consider the application’s operating temperature range when selecting polycarbonate for use in a particular product or component.