TEAM’s Kern micro 24 laser system can be used for high precision cutting and engraving in a variety of substrates; Available materials include plastics (Acrylic, Delrin, being the most common), metals (Steel and Stainless Steel being the most common), wood, and foam (where compatible). See the full list of compatible materials below.
Overview of Laser Cutting:
Laser cutting is a CNC (computer numerical control) driven process by which material is removed via a focused laser beam. The machine has two operation modes: Thru-Cutting, AKA Vector Cutting (where file input = vector file), or Engraving, AKA Raster Engraving (where file input = grayscale graphic).
The laser cutter present in the TEAM lab is a 190W CO2 laser cutter, capable of processing metals and plastics at very high prevision, very rapidly (processing time can be as few as several minutes).
Generally, components derived from laser cutting are flat, with features limited to a single plane (cutting axis). It is common to fix multiple laser cut parts into assemblies by way of interlocking, or stacking features. Bends can also be introduced to many materials to increase complexity of the part/assembly.
By far, the most frequently used materials are: Stainless Steel, Acrylic, Delrin, and King Starboard. Below, is a complete listing of all the materials the TEAM lab can process. Consult with the TEAM lab manager for appropriate thickness where dimensions are lacking, or if you need thicker materials cut.
ABS (acrylonitrile butadiene styrene), up to 0.125 inch thick – Discouraged Material: Poor Cut Quality
Acrylic (also known as Plexiglas, Lucite, PMMA), up to 0.75 inch thick – Common material
Delrin (POM, acetal), up to 0.25 inch thick – Common Material
Kapton tape/film (Polyimide)
King Starboard, Marine-Grade High density polyethylene (HDPE), up to 0.375 inch thick – Common Material
Nylon – Discouraged Material – Poor Cut Quality
PETG (polyethylene terephthalate glycol), up to 0.125 inch thick (discoloration and/or melting at higher thicknesses)
Polyethylene (PE) – melts badly
Polypropylene (PP) – melts somewhat
Teflon (PTFE, Polytetrafluoroethylene), up to ~0.025 inch thick
Styrene/Polystyrene – melts somewhat
Two-tone acrylic – top color different than core material, usually for custom instrumentation panels, signs, and plaques.
Stainless steel (up to 0.060″) – Common material
Spring steel (up to 0.060″)
Cold-Rolled steel (up to 0.08”)
Titanium (up to 0.04”)
Depron foam – often used for RC planes.
Gator foam – foam core gets burned and eaten away compared to the top and bottom hard shell.
Cloth (leather, suede, felt, hemp, cotton)
Rubbers (only if they do not contain chlorine) – up to 0.25 inch thick
Woods (MDF, balsa, birch, poplar, red oak, cherry, holly, etc.) – we stock various thicknesses of birch plywood.
Materials we cannot/will not laser cut:
Polycarbonate (PC, Lexan)
Any material containing chlorine
PVC (Cintra) – contains chlorine
Vinyl – contains chlorine
Glass – we can engrave glass, but we generally cannot cut it.
Printed circuit board (FR4 and other material types)
Precious metals (Gold, Silver, Platinum, etc) – these are reflective, and cam inflict harm or damage optics
Designing for Laser Cutting:
As the laser cutter excels at cutting flat-stock of finite thickness, special consideration must be made when designing for the laser cutter; It’s generally true that your material thickness is a fixed constraint, dependent on what material thickness can be sourced. Further, most all features will be “through” the entire part; partial depth features must (usually) be added through a secondary post-process (hand-finishing, milling being two examples).
While many techniques for developing intricate laser-cut components and assemblies exist, below are a few of the more common approaches:
One significant advantage laser cutting has over other fabrication techniques is the very thin cutting width, known as a “kerf.” We often use this property can be used to our advantage to add flexible joints to pieces
Small Linear Cut Pattern into a Surface to Create 1 Axis Bending Via Laser Kerf
An Enclosure that Uses Kerfing to Achieve a Unique Shape
A Unique Kerfing Pattern to Permit Multi-Axis Bending in an Otherwise Rigid Material
There are a lot of different ways to make joints from flat pieces, and not all are limited to laser cutters, but a lot of the techniques carry over from fields like woodworking and metalworking. Here are a few simple joining techniques for two pieces of flat stock. There numerous other techniques, but here are a few basics:
Finger joints are the basic joint for putting two flat plates together at a perpendicular angle to make a corner. It basically consists of tabs on the mated sides that interlock. The tabs are usually as long as the material is thick to make a nice, clean seam.
Mortise and Tenon Joints
Mortise and tenon joints are very similar to finger joints, except the “fingers” on one piece of material stick through holes in the other piece of material. These are useful for creating “T” like structures and easily mounting internal support beams for more complicated laser cut structures.
Slot joints are another pretty common type of simple laser cut joint. The two connecting pieces each have slots cut halfway through them, which can slide into each other to form “X” like structures out of the laser cut material.
Figure 5: Various Methods of Joinery
Dovetail and Jigsaw Joints
Dovetail joints and jigsaw joints are usually used in laser cutting to mount two materials flush to one another, with even top and bottom surfaces. Although these are more widely used in woodworking, they can come in handy if you’re looking for a certain effect.
Figure 6: A basic Dovetail Joint Used to Mend Two Pieces of Substrate
The above joints will work just fine when the fit is designed to create slight interference (and occasionally with adhesives), but there are instances where removable fasteners are preferred in your designs. By creating a hole for a bolt to slide through and a slot for a nut to be press fit into, you can secure the joints of laser cut parts easily. Also consider, rotating features can be added by way of dowel pins pressed into stock, to create pivot points.
Figure 7: Note the use of Fasteners (Nuts and Bolts) to Fasten Panels Together
One can also stack laser cut pieces (and potentially laminate with solvent, adhesive, or fasteners [screws, dowel pins]) to create 3D features. Breaking up a design into layers is an efficient way to overcome some of the limitations that arise when using the laser cutter
Figure 8: Note the Use of Stacking to Create an Elaborate (Moving) Assembly
Preparing Files for Laser Cutting:
Prior to cutting, parts must be projected onto a 2D drawing file, from the view that the laser cutter will trace out the part. Acceptable file formats include:
DWG file – 2010 format when exporting from Autodesk products
PDF – Vector Format only
Many other vector file formats
Note: Our laser cutter possess the ability to process “offsets” to compensate for laser cutting width, or fine-tune fit of components on-site.
Kern Micro 24, 190 W CO2 Laser:
Positioning Accuracy: +/- .002″/ft
Repeatability: +/- .0005″/ft
Straightness: +/- .002″/ft
Air Assist: Compressed Air, Oxygen, or Nitrogen
Max Cutting Speed: 10”/sec
Max Engraving Speed: 150”/sec, at 30 lines per inch, or 60 lines per inch
Fume Extraction: Vacuum Table, and Overhead Gas Extraction
Maximum Substrate Size: 26”x30”
Maximum Cut Part Size: 23.9”x23.9”