Polycarbonate is a common plastic widely used in various industries. Its diverse uses range from automotive components and optical lenses to medical devices. However, to be used for these purposes, polycarbonate must go through a thorough polishing process that improves its aesthetics and guarantees optical clarity.
In this article, we explore the basics of polycarbonate, its benefits, and various polishing techniques to help you make informed decisions for your polycarbonate projects.
Polycarbonate (PC) Basics
Polycarbonate is an engineering plastic that has a unique combination of mechanical and optical properties. Its tensile strength is between 55 and 75 MPa and its flexural strength is around 90 MPa.
Furthermore, its impact resistance is remarkably high, reaching 850 J/m when measured with the Izod impact test. This impact resistance is around 250 times greater than that of normal glass.
In terms of optical properties, polycarbonate is known for its excellent transparency, which rivals that of glass. Due to its exceptional properties, it is used in applications where strength and visibility are required, such as: For example, glasses, LED light diffusers, glasses, CDs, electrical components and automotive parts.
Advantages of polished polycarbonate
Polishing polycarbonate not only improves its appearance but also its performance. A well-polished polycarbonate surface offers the following advantages:
Greater clarity and light transmission
A polished, transparent surface allows more light to pass through, making it ideal for applications that require high transparency, such as lenses and light diffusers.
Greater scratch resistance and durability
Polishing can create a smoother surface that is less susceptible to scratches and scuffs. This leads to a longer service life of the material and therefore reduces maintenance costs.
Better resistance to chemicals and environmental damage
Polishing can also protect the polycarbonate surface against harsh chemicals and environmental influences, improving its resistance to discoloration and wear over time.
Greater aesthetic appeal
When the polycarbonate surface is polished, it becomes more visually appealing. This is very useful for consumer products and applications where appearance is important.
How to polish polycarbonate: techniques and steps
There are numerous techniques for polishing polycarbonate. From steam sanding and polishing to flame polishing and polishing.
We will explore the basics of each technique, as well as their advantages and disadvantages.
1. Grinding
Sanding is a common surface finishing technique to remove scratches and smooth the surface. It is one of the most used techniques for polishing polycarbonate.
This process uses an abrasive to remove imperfections and create a smooth surface. The process begins with coarse-grit sandpaper (200), followed by progressively finer sandpaper (800 or more) until the desired finish is achieved.
Sanding can be done wet or dry. Dry sanding can cause the surface to heat up and become resinous. Therefore, for best results, wet sanding is recommended as it helps to reduce heat build-up and prevent damage to the surface.
How is polycarbonate sanded? Step by step procedure
The results of the grinding process depend on the skill of the worker and the technique used. Here's a proven technique for getting the best finish:
- Step 1: Gather several sandpapers (e.g. 200, 400, and 600 grit), water, a baby wipe, gloves, an apron, and safety glasses.
- Step 2: Prepare the polycarbonate piece by slightly moistening it, but avoid using excessive water.
- Step 3: Sand the surface gradually. Start with the smallest-grit sandpaper, rub in circles to remove visible scratches, and focus on precision without rushing the process.
- Step 4: Spray water on the surface to prevent dirt from accumulating and keep the sandpaper lubricated.
- Step 5: Continue sanding until the surface is clean and smooth.
- Step 6: For a smoother surface, switch from coarser to finer sandpaper, changing the sanding technique from heavier pressure to lighter pressure.
Advantages of sanding polycarbonate
- Economical and uncomplicated method.
- Suitable for small or large areas.
- It can remove deep scratches and surface defects.
Disadvantages of sanding polycarbonate
- Intensive and time-consuming work.
- If done incorrectly, damage to the surface may occur.
- Experience is required to obtain a uniform finish.
- Does not produce a very smooth and clear finish
2. Steam Polishing
Vapor polishing is a chemical process that uses solvent vapors to dissolve the polycarbonate surface and produce a smooth, shiny finish.
The piece is exposed to steam for a short time, which melts and smooths the surface. Commonly used solvents in vapor polishing polycarbonate are WELDON-4 (methyl acetate, methylene chloride and methyl methacrylate monomer).
Because vapor polishing also creates a fine, shiny surface, this method is often used in applications where high transparency is required, such as optical lenses.
Steam polishing polycarbonate: a step-by-step procedure
- Gather all necessary items. You will need a chemical solvent (e.g. Weld-ON 4), heating equipment (e.g. a kettle), a respirator or mask, and gloves.
- Prepare the polycarbonate surface for polishing by cleaning it.
- Heat the chemical solvent in a kettle to boiling point.
- Gradually apply heated solvent vapor to the polycarbonate surface.
- Watch the surface become lighter, smoother and glossier as the steam melts the polycarbonate.
Advantages of Steam Polishing Polycarbonate
- Creates a high-shine, mirror-like finish.
- Faster than manual sanding and polishing.
It will not result in new scratches or surface defects.
Disadvantages of Steam Polishing Polycarbonate
- Requires special equipment and handling.
- Solvent vapors are toxic; the process must be carried out in a strictly controlled environment.
- Expensive compared to other polishing techniques.
3. Polishing
Polishing is a mechanical polishing technique that uses abrasives and a rotating polishing wheel to produce a smooth, shiny surface. This process is often used in conjunction with sanding to achieve a high gloss finish on the polycarbonate sheet.
As with sanding, polishing also uses polishing agents with different abrasiveness. You start with a thicker mixture and finish with a thinner mixture for a mirror-like finish.
How is polycarbonate polished?
Step 1: You will need the following tools for the polishing process:
- shock absorber
- Loose Blasting Media
- Protective clothing (e.g. gloves, safety glasses)
- Fine grit sandpaper
Step 2: Before you begin, sand the surface of the polycarbonate piece to remove deep scratches.
Step 3: Apply loose abrasive to the polishing machine and then polish the polycarbonate sheet. Avoid holding the workpiece in the same place as this may damage the pad.
Step 4: Hold the polisher firmly. Before turning on the machine, hold it firmly to ensure your safety and complete the polishing process effectively.
Advantages of polycarbonate polishing
- Can produce a high gloss finish.
- Removes fine scratches and imperfections.
- Creates a uniform, smooth finish.
- Cheaper and cheaper.
Disadvantages of polycarbonate polishing
- Chaotic process.
- Severely damaged polycarbonate parts cannot be repaired.
- If done incorrectly, new scratches may occur.
4. Chemical polishing
Chemical polishing involves dipping the polycarbonate part in a chemical solution, which dissolves the surface and smooths out any imperfections.
This method is suitable for complex geometries and difficult to access areas. The solution usually contains a mixture of acids, solvents and other chemicals that selectively dissolve the surface of the material. The commonly used chemical polishing agent is methylene chloride.
How is chemical polishing of polycarbonate carried out?
- For the process you will need a chemical polish (mainly methylene chloride), sandpaper and protective clothing.
- Prepare the piece by sanding the surface to remove any visible scratches. Then wipe it with a damp cloth to remove any residue.
- Apply chemical polishing and wait for passivation to occur. This smoothes and shines the surface while dissolving the top layer of polycarbonate material.
- After the chemical polish has cured, keep the surface under water to prevent cracking due to stress after polishing.
Advantages of chemical polishing
- Can achieve a high gloss finish.
- Suitable for complex geometries.
- Very little labor intensive.
Disadvantages of chemical polishing
- Requires special equipment and handling.
- Expensive compared to other procedures.
- Highly toxic chemicals are used.
- If done improperly, the part can be destroyed.
Polished polycarbonate: maintenance and care
Routine cleaning
To maintain the appearance and performance of polished polycarbonate, regular cleaning is essential.
Gently wipe the surface with a soft cloth and mild soap solution. Then rinse them with water and dry them with a clean, lint-free cloth.
Avoid using abrasive cleaning products or solvents that could damage the surface.
It is also recommended to regularly clean the material with a special plastic cleaner to maintain its clarity and shine.
Avoid scratches and damage
To avoid scratches and damage to the polished polycarbonate surface, always handle it with care.
Store polycarbonate parts with protective covers and avoid placing them on rough or abrasive surfaces.
When cleaning, use only non-abrasive cloths and mild cleaning agents.
Consider using protective films or coatings to add an additional layer of protection against scratches and damage.
Long-term care for a shiny finish
Polycarbonate is prone to yellowing and deterioration over time due to exposure to UV radiation and environmental factors.
Consider applying a UV-resistant coating or opt for a UV-stabilized polycarbonate material.
Regularly inspect your polycarbonate parts for signs of wear, discoloration or damage and correct any problems immediately to maintain their appearance.
Get polishing services for your plastic parts at WayKen
Concluding
By polishing polycarbonate, manufacturers can significantly improve its appearance and durability. This guide looks at several methods, including polishing, grinding, and chemical polishing. By understanding the specific requirements of each technique and following the procedures outlined, you can achieve a smooth, polished finish on your polycarbonate surfaces.
Common questions
What plastic can be steam polished?
Steam polishing can be used on several types of plastics, including polycarbonate, acrylic (PMMA), ABS and polysulfone (PSU).
What should you not use on polycarbonate?
Do not use ammonia, acetone, or alcohol-based cleaners on polycarbonate as they may cause chemical decomposition or discoloration of the material.
What effects does UV have on polycarbonate?
Prolonged exposure to ultraviolet (UV) radiation can have a negative effect on polycarbonate. Yellowing, loss of transparency and deterioration of mechanical properties may occur.
