|
|
Related Names:
Engravers Plastic
Chemical Name:
N/A
Manufacturers:
Rowmark
|
|
|
Microsurface plastic (sometimes called engraver's plastic is a two-part, polymer-based product specifically engineered for CO2 laser systems. The two parts consist of a very thin top layer (~0.001 or 0.025mm) and a thick bottom layer of a contrasting color. These are often called the cap and core, respectively. The cap layer may be a solid color with a matte, satin, or glossy finish. Other varieties include cap layers with metallic fillers to simulate solid brass and aluminum as well as printed wood grain. The core layer is typically a high contrast solid color, such as black or white. Microsurface plastic is also offered with a UV stabilizer, making it suitable for use in outdoor environments.
The plastic chemistry used is typically a blend of acrylic and styrene polymers and copolymers. Styrene is used as a copolymer to break up the closely packed structure of acrylic and impart flexibility. Similar to purer forms of acrylic, microsurface plastic products depolymerize easily under focused infrared energy.
|
|
Microsurface Plastic and DLMP Technology
|
|
The key factor making microsurface plastic compatible with DLMP (Digital Laser Material Processing) is its specific polymer chemistry. This material undergoes rapid depolymerization and vaporization, unlike other materials that may oxidize and char.
The most useful effect of laser energy with microsurface plastic is material ablation.
|
|
Material Ablation
Material ablation is a physical process to remove material from the top to the bottom surface or partially from the top of the material down to a specified depth.
Organic polymers, such as those in microsurface plastic, are excellent absorbers of CO2 laser energy (wavelength=10.6). When the polymer absorbs laser energy, it rapidly converts optical energy into molecular vibrations (heat). Rapid chemical depolymerization occurs with sufficient heat. Depolymerization is the process by which polymers are broken down into their repeating chemical unit. Material directly in the laser path is ablated away into vapor. This effluent may also contain fine particles, such as solid fillers and pigments. The material just outside of the lasers spot or path will conduct some heat, but not enough for complete and thorough combustion and ablation. This area of thermal affect is often referred to as the heat affected zone (HAZ). In microsurface plastic the HAZ is minimal. The newly exposed surfaces may be coated with a layer of sticky residue. This residue can be removed with a common solvent, such as denatured alcohol. If it is not removed the residue will harden overnight.
Laser Cutting
|
Laser cutting is the complete removal and separation of material from the top surface to the bottom surface along a designated path.
Microsurface plastics are ideal to cut using DLMP technology. The edges created from laser cutting will show virtually zero discoloration. Only a slight residue will remain on the cut edges, which is easy to remove with denatured alcohol or other common solvent. If the use of solvents is not feasible, the residue will harden overnight in most cases.
The example shows a simple square with rounded edges cut from a sheet of microsurface plastic. From the cut edge, the core (bottom) layer of the plastic is visible. The basic capability shown can be extended to nearly any shape, even complex and closely-spaced cuts.
|
|
|
|
Laser Marking And Engraving
|
|
|
|
|
When laser energy is used to produce a human- and/or machine-readable identification or information on a material (e.g., barcode, date/lot code, serial number or part number), the process is called laser marking. When depth is created, with or without accompanying contrast, the process is referred to as laser engraving. Laser marking and laser engraving microsurface plastic are the same process, because material must be removed to create useful contrast (i.e., mark). The example image shows alphanumeric characters marked, or engraved, on microsurface plastic
|
Material Modification
Material modification is a physical process altering the properties and/or appearance. Laser marking does not yield a useful result with microsurface plastic. The interaction between the laser and the material melts the surface and does not result in a mark to the surface.
Combined Processes
|
|
Multiple processes can be applied to microsurface plastic without having to move or re-fixture the material. The example demonstrates how processes can be combined to cut square and round shapes and mark/engrave with microsurface plastic and DLMP technology.
|
|
|
Environmental, Health and Safety Consideration
Laser material interactions almost always create gaseous effluent and/or particles. Processing microsurface plastic (Rowmark LaserMark brand) with a CO2 laser generates vapors primarily containing methyl methacrylate, diethyl ether, cyclopropanecarboxylic acid, acetic acid, ethyl acrylate, methyl isobutyrate, and propionic acid. The effluent from processing microsurface plastic should be routed to the exterior environment. Alternatively, it may be treated with a filtration system first and then routed to an exterior environment. Vapors from laser processing acrylic and styrene based products such as this are flammable. Laser processing microsurface plastic should always be supervised.
