PLASTICS AND POLYMERS

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2. General description

Plastics and polymers form a vast family of organic materials composed of macromolecular chains. Gradually introduced into horology in the 20th century, they now hold an important place, both in the external parts (case, dial, hands) of watches and in certain quartz movements, or even mechanical ones, as well as in tooling. Their success is based on their low mass, their wide diversity of properties and their ease of shaping, which allows complex parts to be obtained at controlled cost. Depending on their nature (thermoplastics, thermosets or composites), they can meet varied requirements ranging from External parts (case, dial, hands) to functional components of the Movement.

3. Types of polymers used in horology

Thermoplastics

Thermoplastics can be melted and reshaped.

Examples:

• ABS → cases, economical components
• PMMA (plexiglass) → watch crystals
• Polycarbonate (PC) → resistant transparent elements
• PEEK → technical applications

Thermosets

These polymers harden irreversibly after polymerization.

Examples:

• Epoxy resins (composite matrices)
• Phenolic resins

Used notably in composites (Carbon, etc.).

High-performance technical polymers

Some polymers offer advanced properties:

• PEEK (polyetheretherketone)
• PTFE (Teflon)
• PA (technical polyamides)

Characteristics:

• Good mechanical resistance
• Low friction coefficient
• Improved thermal resistance

4. Manufacturing Methods

Polymers are shaped using various industrial processes:

Plastic injection

• Melting of the polymer
• Injection into a mold
• Cooling and solidification

👉 Most common process in industrial watchmaking

Machining

• Cutting from solid stock
• Used for technical polymers

Compression / molding

• Used for resins and composites
• Allows complex shapes

Additive manufacturing (more marginal)

• 3D printing
• Prototyping or small series

5. Horological applications

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External parts (case, dial, hands)

• Cases (sports watches, budget watches)
• Straps
• Crystals (PMMA)

👉 Advantages: lightness, impact resistance, cost

Movement

• Wheels and pinions (specific applications)
• Anti-friction components
• Insulating parts

6. Advantages and limitations

Advantages

• Very lightweight
• Low cost
• Great design freedom
• Corrosion resistance
• Non-magnetic
• Electrical insulation
• Possibility of self-lubrication
• Good impact resistance (certain polymers)

Limitations

• Low rigidity
• Sensitivity to Temperature
• Aging (UV, oxidation)
• Limited mechanical resistance
• Less noble than traditional Materials
• Sensitivity to scratches (depending on polymer)