Winklewagen CNC Laser Graveer Machine: How It Marks Metal

• 1
  What Actually Happens at the Focal Point
• 2
  Frame, Guides, and Why Ripple Shows Up
• 3
  Which Materials a Winklewagen CNC Laser Graveer Machine Handles
• 4
  Depth, Contrast, and Heat-Affected Zone
• 5
  Design Rules That Keep the Mark Readable
• 6
  Laser Marking vs Mechanical Engraving vs Hybrid

A laser graveer does not cut with a blade. It focuses a beam down to a spot a few hundredths of a millimeter wide and lets the material absorb that energy. Absorbed energy turns into heat within nanoseconds. The surface either melts, vaporizes, or changes phase, depending on how fast the heat can leave the spot. The spot stays hot only as long as the beam dwells there, which is set by feed rate, pulse frequency, and hatch spacing.

The depth you get is not a fixed number on a datasheet. It is the result of energy density multiplied by time. On a 20 W fiber source, a single pass at 800 mm/s might remove 0.01–0.02 mm. Ten overlapping passes at 200 mm/s can reach 0.3 mm. Push further and you start to see dross, recast, or a heat-affected zone that changes hardness. That is the boundary most people miss.

Absorption is wavelength-dependent. A 1,064 nm fiber beam couples well into steel, stainless, aluminum, and titanium because their free electrons absorb near-infrared light. Bare copper and brass reflect most of it at room temperature, so they need higher peak power or a green 532 nm source. Organic materials like ABS, PMMA, and anodized layers absorb 10,600 nm CO₂ light far better than near-infrared.

This is why two machines with the same wattage behave differently. Source type, spot size, and pulse shape matter more than the number on the nameplate. A 30 W fiber with a 50 μm spot and good pulse control will out-mark a 50 W unit with a 100 μm spot on thin stainless.

Laser graveer machines move the head or the table on linear guides driven by stepper or servo motors. Vibration during a raster pass shows up as ripple on the engraved edge, so the frame is usually a single welded structure rather than bolted sections. A heavier gantry resists acceleration-induced flex, but it also needs more torque to reverse direction. That trade-off sets the practical raster speed.

Backlash in the drive train is the other source of ripple. If the X axis reverses and the nut has 0.02 mm of play, every hatch line starts with a small offset. On fine text under 2 mm tall, that offset is visible. Machines with preloaded ball screws or belt tensioners hold tighter, but belts still stretch over time and need re-tensioning.

Control software reads vector or bitmap input and converts it into toolpaths. DXF, DWG, and AI files go through as vectors. Raster images are converted to grayscale power maps, where darker pixels get more power or more passes. The controller decides pulse timing, so a weak controller on a strong source still produces uneven depth.

Thermal drift matters on long runs. A 4,000 mm table can grow 0.05 mm over an hour of continuous marking as the frame warms. For serial-number runs that is fine. For a 200 mm long scale with 0.02 mm division spacing, you need either temperature compensation or a slower, cooler duty cycle.

Stainless steel 304 and 316 mark cleanly with a fiber source. Annealing marks give a dark, oxide-free contrast that survives passivation. Ablation marks cut deeper and look brighter but leave recast. On 316L for medical parts, annealing is usually the safer choice because it does not disturb the passive layer.

Aluminum and its alloys mark well, especially with a 20–30 W fiber source. Anodized aluminum is the easiest case: the beam removes the dye layer and exposes the substrate, giving high contrast at low power. Bare 6061 needs more energy and often a two-pass approach to get a readable dark mark without pitting.

Copper, brass, and bronze are the difficult group. Near-infrared reflectivity at room temperature can exceed 90%. Preheating, higher peak power, or a green source resolves it. Beryllium copper adds a health concern: the vapor is toxic, so extraction is mandatory and the operator needs respiratory protection.

Plastics behave differently. ABS and POM melt and re-solidify, leaving a raised bead. PMMA vaporizes and can produce a flame-polished edge if the pulse is short. PEEK and PA absorb well but char if power is too high. Carbon fiber reinforced plastics mark with a gray, low-contrast result because the resin and fiber respond differently, so the mark looks mottled under magnification.

Depth is controlled by three variables you can log: average power, scan speed, and number of passes. Increasing power by 50% roughly doubles energy density, but it also widens the heat-affected zone. Slowing the scan speed has the same effect on energy density but spreads heat over a longer time, which can warp thin sheet. More passes with lower power per pass gives the most control and the least distortion.

Contrast on stainless comes from either oxidation or surface roughening. Annealing produces a dark oxide that reads black under diffuse light. Roughening produces a matte mark that reads black under directional light and can disappear under a different angle. For parts that will be inspected under fixed lighting, specify which mechanism you want, and state the viewing angle on the drawing.

The heat-affected zone on a 0.5 mm stainless shim can reach 0.2 mm in depth with aggressive settings. That zone is harder and more brittle. If the part flexes in service, the mark becomes a crack initiation site. For thin walls, use low power, high frequency, and multiple fast passes. This keeps the peak temperature down while still building depth.

On curved or angled surfaces, focus drifts. A 30° slope on a 300 mm part can move the surface 1–2 mm out of the focal plane, which changes spot size and depth. Rotary tables with a Ø400 mm capacity help for cylindrical parts, but the controller must compensate for the changing surface distance. Without that, the mark gets lighter on one side.

Minimum character height for a legible mark is about 1.5 mm. Below that, the stroke width drops under 0.05 mm and the mark becomes a scratch rather than a character. If your drawing calls for 0.8 mm text, either enlarge it or switch to a different marking method.

Line width follows spot size, not the vector width in your file. A 50 μm spot produces a 50–70 μm line with a single pass. If your drawing specifies a 0.2 mm line, the controller will hatch it with multiple passes, which slows the cycle and deepens the mark. Tell your supplier whether the line width is functional or cosmetic.

Datum placement matters. Put the mark on a flat face, not next to a fillet where the surface curves away from the focal plane. Keep 2–3 mm of clearance from edges so the beam does not clip the part and reflect. On small parts, the fixture sometimes covers the best marking face, so discuss fixturing before the drawing is frozen.

Finally, decide whether the mark is decorative or traceable. A traceability mark for aerospace or medical use usually needs a defined contrast level, a defined depth range, and a documented inspection method. A decorative logo needs neither. Mixing the two on one drawing is the most common cause of back-and-forth during first article inspection.