Natural Rubber (NR)

Physical properties

Laser processing

Combustion of natural rubber releases isoprene, benzene, polycyclic aromatic hydrocarbons (PAHs), and dense black smoke. Not classified as acutely toxic as synthetic neoprene rubber, but fumes are irritating to the respiratory tract and require extraction with activated carbon filter.

CO₂: Cutting possible on thin sheets and slabs (≤5mm) with medium power and high speed. Rubber tends to burn at edges, producing carbonaceous residues. Best results with abundant air assist. Engraving produces clean grooves but with an intense odor.

Diode: A 10W+ diode laser can superficially engrave natural rubber. Full cutting requires high power and multiple passes.

Fiber: Not applicable.

CNC / milling processing

CNC machinable only on rigid solid forms (in certain grades of hard vulcanized rubber). Flexible rubber cannot be milled in a controlled manner due to elastic deformation under stress. Sharp single-flute tools with high feed rate.

Plotter and thermoforming

Good machinability with blade plotter on natural rubber sheets up to 3mm. Use blades with calibrated offset to compensate for elastic deformation during cutting.

Post-processing

Sanding: Sandable with coarse-grit abrasive paper. Rubber tends to clog sandpaper due to its elasticity and surface tackiness.

Gluing: Bondable with contact adhesive (neoprene) on both surfaces. Natural rubber is self-adhesive with solvents such as hexane — follow solvent safety regulations.

Over time: Natural rubber progressively oxidizes and hardens through exposure to air, ozone, and UV light. It cracks and loses elasticity over years. Vulcanization delays the process but does not eliminate it.

Common defects

• Surface oxidation with loss of elasticity and crack formation after prolonged UV exposure
• Laser cut edges leave carbonaceous residues that soil adjacent surfaces
• Sensitivity to ozone and hydrocarbons that degrade the polymer structure

Safety

Caution with latex allergy: natural rubber is derived from Hevea brasiliensis and can cause mild to severe allergic reactions in sensitized individuals. Always check before using in shared environments. Combustion fumes are irritating.

Availability and formats

Commercial formats: sheets 1–10mm, rolls, extruded profiles

Sources

• ISO 37 — Rubber determination of tensile stress-strain properties
• Schede tecniche fornitori gomma naturale vulcanizzata