Which Frame is better: Plastic vs. Metal

Eyewear frames on the market are primarily divided into two categories: plastic and metal.

1. Plastic Frames

Plastic frames are further categorized into injection-molded and sheet materials.

1.1 Injection-Molded Materials

The injection molding process involves melting plastic pellets (mainly PC, TR, and plastic steel) and injecting them into molds, where they are cooled and shaped.

• Advantages: High dimensional stability in bulk production, fast processing speed, and low overall cost.
• Disadvantages: Most frames are surface-treated with paint, which is prone to wear, fading, and peeling.

Common materials in this category include:

• A. PC (Polycarbonate)
  Also known as “space film,” PC material is very impact-resistant. Frames made of PC thicker than 10mm are even used as bulletproof glass.

• Advantages: Low material cost, certain flexibility, impact resistance (hence the “space film” nickname), and cracking without debris.

• Disadvantages: The surface paint is not environmentally friendly, and the coating tends to peel. The comfort and durability are lower, and the frame cannot be adjusted to fit different face shapes.

  
  

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• B. TR (Thermoplastic Resin)
  TR material is widely used and is often referred to as "memory plastic." It has excellent flexibility and is commonly used in modern eyewear frames.

• Advantages: High transparency, excellent flexibility, adapts to different sizes, highly resistant to compression and pressure (breakage usually occurs only if recycled materials are added), and is very lightweight.

• Disadvantages: The surface paint treatment is not eco-friendly and may peel off in about two years. The frame cannot be adjusted due to its excellent elasticity, and the softness can make it easier for unskilled workers to fit lenses poorly into the frame.

  
  

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• C. Plastic Steel (Wung Titanium)
  Known for its increasing popularity, plastic steel frames offer a good balance between strength and flexibility.

• Advantages: Higher strength and surface hardness compared to TR, slightly more flexible than PC, and lightweight. Due to its strength, it can produce very thin, metal-like frames. The paint adheres well to the surface.
• Disadvantages: The matte finish requires a high-quality paint job, and poor painting techniques may cause the frame to become brittle and break.

• D. Carbon Fiber
  Often used in decorative parts like temples.

• Advantages: Extremely lightweight, high strength, high-temperature resistance, and a unique surface texture.

• Disadvantages: Can break easily when bent excessively.

  
  

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1.2 Sheet Materials

Sheet materials are pre-made into flat plates (approximately 5-8mm thick) and then cut into the required frame or temple shapes.

• A. Acetate (Cellulose Acetate)
  The most common sheet material on the market, acetate is frequently used in fashion eyewear.

• Advantages: High surface hardness, no need for surface treatment, luxurious texture, and scratch resistance. It can also be adjusted for comfort to fit different face shapes, which makes it popular in high-end eyewear brands.
• Disadvantages: The material is relatively hard, which may cause discomfort if not properly adjusted. It cannot be paired with PC lenses, as this may cause lens cracking. Acetate is heavier than other materials and may need to be adjusted for a perfect fit.

• B. Heamani
  Not widely used in the market yet but has been available in foreign markets for over six years.

• Advantages: Perfectly accommodates embedded materials like thin slices of real dried flowers, stainless steel, denim fabric, lace, etc., creating a multi-dimensional, textured look. The material is lighter than acetate and has better flexibility. It is also highly durable and can be adjusted for a better fit.
• Disadvantages: Lower surface hardness compared to acetate, and the texture is not as refined.

2. Metal Frames

Metal frames are commonly made from alloys, stainless steel, titanium, or β-titanium, each offering different qualities in terms of strength, flexibility, and durability.

2.1 Alloy Materials

Alloys such as white copper (primarily copper with added nickel and zinc), manganese-nickel (mainly manganese and nickel), and nickel-copper (primarily nickel with copper) are commonly used in eyewear.

• Advantages: These materials are inexpensive (especially white copper) and easy to process. They are also easy to adjust for a customized fit.

• Disadvantages: Poor corrosion resistance, prone to rust, may cause metal allergies, and can easily bend under pressure. Additionally, these materials are relatively heavier.

2.2 Stainless Steel

Frames made from thin stainless steel sheets are punched into shape.

• Advantages: Excellent flexibility and resistance to deformation, lightweight, and strong surface coatings (IP plating) for durability.

• Disadvantages: Difficult to adjust, and frames with high prescription lenses may look bulky and affect the aesthetics. Frames with spray-painted coatings tend to lose paint quickly and are not very durable.

2.3 Titanium

Frames made from titanium with a purity of at least 99% are considered high-end materials in eyewear.

• Advantages: High strength, resistance to deformation, corrosion-resistant, and lightweight. Frames are highly durable, and the IP plating ensures a long-lasting finish.

• Disadvantages: The material is expensive, and its high processing difficulty leads to higher prices.

  
  

  

2.4 β-Titanium

β-Titanium is a molecular variation of pure titanium and is often used for high-elasticity frames such as thin temples, nose pads, and ultra-light frames.

• Advantages: Excellent flexibility, resistance to deformation, and lightweight.
• Disadvantages: Not suitable for people with high prescriptions, as thicker lenses can make the frame front-heavy and cause slipping. The material is expensive and difficult to process.