Laser cutting and marking of plastics is a widely used industrial process that leverages the power of focused light beams to slice through or imprint designs onto various plastic materials. This technology is prized for its ability to deliver high precision, speed, and quality finishes that are often difficult to achieve with mechanical tools.
How It Works
The process involves directing a high-powered laser beam onto the plastic surface. Depending on the laser settings and the type of plastic, the beam heats the material to melt, vaporize, or chemically alter it.
For Cutting: The laser typically vaporizes the plastic along a defined path, leaving a clean, sealed edge.
For Marking: The laser modifies the surface properties, changing the color or texture without cutting all the way through. This can occur through methods like carbonization (darkening), foaming (creating bubbles for a lighter mark), or ablation (removing a surface layer).

Key Processes
There are distinct techniques used depending on whether the goal is to separate material or add information to it:
Process
Description
Ideal For
Laser Cutting
Uses heat to slice through the full thickness of the material.
Creating shapes, prototypes, and parts with intricate geometries.
Laser Engraving
Vaporizes a thin layer of material to create a depression.
Adding texture, deep logos, and 3D effects.
Laser Marking
Alters the surface color or structure (e.g., color change) without removing material.
Barcodes, serial numbers, and QR codes where surface smoothness is important.

Types of Lasers Used
Different plastics react differently to light wavelengths, requiring specific laser types:
CO2 Lasers: The industry standard for cutting plastics like acrylic. They operate at a wavelength that most plastics absorb well, allowing for fast cuts and polished edges.
Fiber Lasers: Primarily used for marking engineered plastics (like ABS or polycarbonate). They create high-contrast marks but are generally not efficient for cutting transparent plastics.
UV Lasers: Known as “cold marking,” these use high-energy ultraviolet light to mark heat-sensitive plastics without causing thermal damage or burns.

Suitable (and Unsuitable) Materials
Not all plastics are safe or suitable for laser processing.
Excellent Candidates:
Acrylic (PMMA): The most popular choice; cuts cleanly and leaves a “flame-polished” edge.
Polypropylene & Polyethylene: Cut well but may have slightly raised edges.
Delrin (POM): excellent for precision gears and mechanical parts.
Polycarbonate: Good for thin sheets, though thick sheets can discolor or yellow.
⚠️ DO NOT LASER:
PVC (Polyvinyl Chloride): When laser cut, PVC releases chlorine gas, which creates hydrochloric acid. This is toxic to humans and will destroy the laser machine’s optics and mechanics.

Advantages
Laser processing offers distinct benefits over mechanical cutting (like CNC routers or saws):
Polished Edges: especially with acrylic, the laser leaves a crystal-clear, smooth edge that requires no post-processing.
Precision: Capable of cutting extremely fine details and sharp corners (with a radius as small as the laser beam).
No Mechanical Stress: Since it is a non-contact process, there is no physical force applied to the part, preventing clamping damage or warping.
Speed: fast setup and processing times make it efficient for both prototyping and mass production.

Applications
Signage & Displays: Point-of-purchase displays, illuminated signs, and lettering.
Automotive: Dashboard buttons (day & night design), ID tags, and backlit components.
Electronics: Housing enclosures, keyboard marking, and circuit board cutting.
Medical: Traceability markings on medical devices and surgical tools (often using UV lasers to ensure sterility).