IN THE LOOP: SUNDAY DRIVER

The free-form, complex shapes of golf clubs are challenging to design and even more challenging to change. When a designer wants to test a new club shape or size, s/he must often model the design in clay and then digitize it, then create a digital solid model for testing, and sometimes even make a physical rapid prototype as well. If the club design has been physically modeled in a soft material like clay, non-contact laser scanning is the ideal method to digitize the entire topography without altering or damaging the surface.

For example, a Surveyor FA portable 3D laser scanning system with the 12 ft Faro arm was recently used to scan a square-headed driver that had to be redesigned. The surface of the club was very shiny, but the engineers did not want to use surface spray on the driver. Instead, they decided to use a thin layer of car wax to mitigate the specularity of the club before scanning. Then they used software filters and Point Cloud DeNoiser software to minimize the "noise" generated off shiny surfaces.

The golf club head's free-form, complex shapes were captured very accurately by laser scanning. Because this portable 3D scanning system projected a line of laser light onto all of the part's surfaces while its cameras continuously triangulated the changing distance and profile of the laser line as it swept along, the problems of missing data on the irregularly-shaped surface were greatly reduced.

The laser line moved back and forth over the part's surface until the complete area was captured digitally. The system measured details and complex free-form geometry so that the object could be exactly replicated digitally. Typical laser scanners measure articles quickly, picking up to 75,000 coordinate points per second to generate huge numbers of data points without the need for special templates or fixtures.

The portable system used to scan this golf club utilizes an SLP-400 laser line scanning probe that allowed the operator to move it over and around the club's surface completely. Mounting the club on V-blocks gave the operator access to a 360 deg view of the driver's head. The system's native software, Surveyor Scan Control (SSC), took only a few minutes to set up.

The desired scan data density was predetermined by the operator. The pre-processed raw data of the golf club head comprised over two million coordinates. Millions of coordinates are usually kept to adequately define the part being scanned for either reverse engineering or inspection. A typical scan density for this type of part is 50,000 to 100,000 points per square inch, but almost any density can be preset by the operator.

This portable scanning system was accurate to ± 0.004 in. Scan time for the golf club head was approximately 30 minutes. Without non-contact laser scanning, capturing enough data coordinates to accurately define the club's shape would have taken at least 20 times longer and would have resulted in a much less complete data set. After the 3D laser system scanned the entire golf club, the native software automatically connected the point cloud data from multiple views into a common coordinate system in a single scan file.

Laser scanning is ideal for reverse engineering complex parts to create STL and/or CAD models because the whole surface of an object is scanned, not just a limited sample of discrete points like in contact measurement. Parts can be modeled "as is" for exact replication or the original design intent of the prismatic shapes can be extracted even if the as-built part is warped, misaligned, or broken – as is typically the case in mass produced products.

When taken into a solid modeling CAD package, the "history" of the model is available to designers, so any version may be referred back to at any time in the re-modeling process. From that point, design changes or variations can then be easily made.

During the driver redesign, Geomagic Studio was used to create an STL model of the scan data. Geomagic Qualify Inspection software was used to compare the scan of the part to the CAD model showing discrepancies in a 3D color error map. In this case, the scan data was used for confirming the accuracy of the reverse engineered model that was developed. However, this same scan data could also be used for inspecting manufactured parts against the intended perfect CAD model for insuring manufacturing tooling and production processes.

Another application for the golf club scan data is to ensure the fit between the club head and the club shaft. High-accuracy laser scan data from the shaft cavity of the club head can be used to manufacture a shaft that mates perfectly to it, ensuring the fit, function, and performance of the whole club.

This easy-to-set-up portable system, combined with the high-speed laser scanning technology, made the entire scanning process fast, user-friendly, and ultimately less expensive than using other measurement methods that would have been extremely difficult and expensive because of the complexity of the driver's shape and surface textures.

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Mary Storms is the marketing director for Laser Design/GKS Inspection Services, 9401 James Ave South, Bloomington, MN 55431, 952-252-3433, www.gks.com.