Naturally occurring inorganic materials like stones and gems are hard, non-metallic minerals. Gems consist of a single type of mineral, while rocks are aggregates of several minerals. Shells have similar composition and properties to stones and gems. However they grow from living organisms, so they are not classified as minerals. All of these materials can be laser marked and laser engraved. In some cases, they can be laser cut. Visit our Materials Suppliers List for natural inorganic material vendors.
Types of Natural Inorganic Materials
Lasers are playing an ever expanding role in material processing, from new product development to high volume manufacturing. For all laser processes, the energy of a laser beam interacts with a material to transform it in some way. Each transformation (or laser process) is controlled by precisely regulating the wavelength, power, duty cycle and repetition rate of the laser beam. These laser processes include the following:
All materials have unique characteristics that dictate how the laser beam interacts and consequently modifies the material. The most common processes for natural inorganic materials are the following:
Laser Cutting of Natural Inorganic Materials
The energy of a CO2 laser beam is easily absorbed by natural inorganic materials. The laser beam heats the material directly in its path, causing it to vaporize. However, because natural inorganic materials are brittle, this local heating can cause the material to fracture before the laser beam can cut completely through. If the material is less than 0.010” thick (2.5 mm), the laser beam can cut through the material without fracturing. Mother of pearl is usually thin enough to be laser cut cleanly, with smooth edges and no chipping.
Laser Engraving of Natural Inorganic Materials
The power of the CO2 laser beam can be limited so that it removes (engraves) material to a specified depth. The laser engraving process can be used to create patterns and designs in the surface of natural inorganic materials. Laser engraving can also be used to convey information.
Laser Marking of Natural Inorganic Materials
Most natural inorganic materials can be laser marked using a CO2 laser beam. The energy of the laser beam causes micro-cracks to from on the surface of the material. The micro-cracks scatter light, causing the marked area to appear lighter and brighter than unmarked area. Laser marking can be used to create designs or to convey information.
The laser engraving and marking processes described above can be combined without having to move or re-fixture the material. Only very thin natural inorganic materials can be laser cut. So this process is not usually combined with other laser processes.
General Natural Inorganic Materials Laser System Considerations
Platform Size – Must be large enough to hold the largest pieces of natural inorganic material that will be laser processed or be equipped with Class 4 capability for processing larger pieces.
Wavelength – The 10.6 micron wavelength is absorbed well by most natural inorganic materials and is recommended for laser cutting, engraving, and marking.
Laser Power – Must be selected based on the processes that will be performed. 25 to 150 Watts (CO2 laser) is best for laser marking natural inorganic materials. Higher laser power should be used for laser cutting and engraving.
Lens – A 2.0 lens is the best general process lens for natural inorganic laser material processing.
Cutting Table – Supports thin sheets of natural inorganic materials, like mother of pearl, for laser cutting.
Exhaust – Must have sufficient flow to remove the gasses and particles that are generated during laser process from the laser cutting, engraving, and marking equipment.
Air Assist – Provides a jet of air near the focal point of the laser to help remove gasses and particles that are generated during natural inorganic material laser engraving, cutting, and marking.
Environmental, Health and Safety Considerations for Natural Inorganic Laser Material Processing
Laser-material interactions almost always create gaseous effluent and/or particles. The effluent and particles from natural inorganic laser material processing should be routed to an exterior environment. Alternatively the exhaust may be treated with a filtration system first and then routed to an exterior environment. Combustion is inherent to laser processing and may produce flames. Therefore laser material processing should always be supervised.