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Dayton Rogers

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How to Design Metal Stampings
Things We've Learned From Years Making Metal Stampings

24. Laser Considerations

In addition to production economics, precision and edge condition, the knowledgeable designer considers these characteristics of laser produced parts when designing for lasers:

Localized Hardening. Lasers cut by melting or vaporizing metal. This can create problems when cutting heat treatable materials as the area around the part will become case hardened.

Laser cut holes in stainless steel or heat treatable steel alloys which require machining (tapping, countersinking or reaming) can be particularly troublesome. By the same token, designers can employ this characteristic to their benefit when a product must be case hardened for wear resistance.

Edge Taper. The laser is most accurate where the coherent light beam enters the workpiece. As the beam penetrates the part, the light scatters creating an edge taper condition similar but opposite from "breakout" in a sheared or pierced part. (The hole on the side of the workpiece from which the laser beam exits is generally smaller in diameter than on the entrance side.)

Thus the designer must carefully consider the final use of the part and, in some cases, may have to specify from which side the part should be cut.

Minimum Through-Feature Size. The cutting laser beam is focused down to approximately 0.010" (0.2 mm) and is therefore capable of cutting holes and features with radii approximating 0.030" (0.76 mm). The limits applicable to piercing or blanking with a punch and die, such as the relationship between minimum hole size and material thickness, or the minimum distance between features to avoid distortion, do not apply when laser cutting.

However, some limitations do exit, and are also related to the material thickness (see table below). Laser cutting allows for through-features to be 1/6th to 1/8th the size when compared to die piercing.

Also, since no mechanical force is applied, the width of material remaining between cutout features may be very narrow without distortion occurring during metal removal. A typical application would be tight spaced venting slots on a visually important surface.

Minimum Through-Features
Material Thickness
Range
Minimum Hole Diameter and
Slot Width Achievable
in. mm in. mm
0.000-0.075
0.075-0.090
0.900-0.125
0.125-0.156
0.156-0.187
1.0-1.9
1.9-2.3
2.3-3.2
3.2-4.0
4.0-4.8
0.010
0.015
0.020
0.025
0.030
0.25
0.38
0.50
0.64
0.76

This technical information has been contributed by
Dayton Rogers

Click on Company Name for a Detailed Profile

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