Laserdyne systems solve fabricating challenges

Prima North America has detailed how its Laserdyne multi-axis laser machining systems have helped LAI International to solve fabricating challenges.

The supplier of precision components and sub-assemblies for OEMs operates seven multi-axis laser systems at its facility in Maine; five Laserdyne 780 Beamdirectors and two Laserdyne 890 Beamdirectors.

LAI also operates three additional Laserdyne systems with 94W laser process controls at its facility in Tucson, Arizona.

The workstations can handle rotary parts up to 48in diameter, pre-formed parts up to 24in high, and materials thicknesses from the thinnest gauges to 1in.

Rich Technology International is a diversified contract manufacturer and one of the five LAI International manufacturing facilities dedicated to supplying of precision engineered components and assemblies for the aircraft, power generation and defence industries.

With its laser systems, Rich Technology International does high-volume work and specialises in processing difficult materials such as Inconel, stainless steel, super-cobalt alloy, hybrid nickel, chrome steel and Hastelloy X.

Half of its laser jobs are for the aerospace industry and the other half is devoted to land-based turbines.

Some of the work can not be done efficiently using other processes such as EDM or waterjet machining.

The laser work can call for drilling thousands of holes in a single part, from 0.003in diameter rounds, to percussion drilling and trepanning special shapes.

Drilling angles range from 90 degrees to as low as 10 degrees to the surface.

A typical job - spacer bands for land-based turbines - requires laser cutting a series of accurately spaced complex profiles along the part contour.

Part runs for this job average 40 to 50 sets a week using one of the refurbished Laserdyne 890 Beamdirector systems equipped with a 3,000W CO2 laser.

The material is 440-grade stainless steel with a chrome additive - a very hard material - but processed efficiently on the system with smooth, burr-free edges.

Accuracies are a tight 0.004in true position total tolerance for the special airfoil shape and speeds are relatively fast considering the geometry of the part features.

Laserdyne's Automatic Focus Control (AFC) guides the motion system, maintaining critical focus position and following the contour of the part regardless of slight surface irregularities.

With AFC, all machine axes react to sensing of the part surface, creating unlimited R-axis correction with high speed and sensitivity.

AFC allows top machine speeds so productivity is maximised without downtime or scrapped parts.

LAI International uses trepanning, percussion drilling, and drill on the fly laser processing techniques in which the AFC feature is important in the laser drilling processes.

Trepanning is a process for creating holes where the part is held stationary and the laser beam is moved with simultaneous multiple action motion to create a round hole or any feature by cutting the periphery of the shape.

Laserdyne's accurate and repeatable laser positioning systems allows for tight tolerance trepanned features.

In contrast, percussion drilling delivers one or more pulses from the laser to a part while the laser beam and part are stationary.

More than one pulse may be required depending on the material type and thickness.

A variation of percussion drilling is 'drill-on-the fly' where pulses are delivered to the part by the stationary laser while the part is rotated.

The hole placement is a function of rotational speed and laser pulse frequency.

If multiple pulses are required, 'drill-on-the-fly', software developed by Laserdyne engineers, is utilised to synchronise the movement of the part to the laser pulses, ensuring that multiple pulses are delivered to the exact location required.

By changing the laser pulse energy, pulse count or lens focal length, the characteristics of the drilled hole size and taper can be controlled to meet the requirements of the part.

Drill-on-the-fly software also allows changes of the pulse shape during the process to improve hole geometry.

With equipment options that include waterjet and EDM, Eric Nelson, vice-president and chief technology officer at LAI International's equipment preference for laser drilling aircraft vane sector components is a Laserdyne system with a Beamdirector because it provides higher feed rates and is more accurate.

Multi-axis laser machining is essentially a non-contact process so highly rigid part clamping is not required.

Using an updated Laserdyne 780 Beamdirector equipped with a 1,500W CO2 laser, 1,500 to 2,000 of these parts are laser processed at LAI, week after week, with only minimal operator adjustments.

Repeatability with positioning accuracy is a cumulative result of many factors working together that affect the overall laser system's accuracy and the quality of the parts produced.

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