Advancements in Blue Laser Scanning

Blue laser scanners are typically fixed to the end of a portable articulating arm while structured blue light is typically attached to the end effector of a robot. Both technologies offer accurate, software-driven solutions that can catch costly errors earlier and help make more of a quality product faster.

Common applications of the technology include:

• Non-contact Inspection: Inspect freeform shapes or parts too soft for contact digitization
• Inspection/Dimensional Analysis: Measure and compare parts to nominal data.
• CAD-based Inspection: Measure directly against CAD data; see surface defects in real time and color map deviations from nominal.
• Rapid Prototype/Manufacture: Digitize design geometry and/or qualify parts to design.
• Reverse Engineering: Digitize parts to simply document as manufactured conditions, or create basic surfaced or complex, fully parametric CAD models.

Red or blue laser?

While red lasers are still powerful and effective, the increased adoption of 3D measurement means industry is continually seeking other areas of benefit. But limitations such as dark or reflective surfaces that required pre-coating, time to capture scan data due to slower point collection rate, or post-scan processing to clean up areas of “noise,” paused the expansion or disqualified the tool.

High-definition blue laser scanning and structured blue light scanning offer increased speed while high accuracy supports the ability to meet the demands of tighter tolerance inspections. A high-resolution scan captures clear, noise-free data and intricate three-dimensional details of the object. Also, blue light can scan challenging surfaces including dark and reflective materials.

How They Work

An articulating arm with the high-definition blue laser attached has special encoders at each arm joint that can compute the exact position and orientation of the probe within three-dimensional space by calculating their relative positions and angles. Clicking a button at the end of the arm allows the equipment to record the location of the probe on the part as a measurement point within the software.

A blue laser-line probe can then be attached and calibrated to the location of the probe. This empowers the operator to capture hundreds of thousands of these measurement points of data optically (vs. hard probing). The high-performance laser projects a beam, comprised of 2000 points, onto the surface of the object. A digital camera looks at the beam to determine the location for each of these points in 3D space. Scan results are captured in a detailed, three- dimensional, point cloud, within the software.

An example is in the case of a casting. Blue laser scanning, or blue light scanning, coupled with software that can load in the CAD model of the final machined part means that it is possible to scan the casting and analyze if there is:

Too much stock: This can lead to wasted machine hours and unnecessary material scrap. It could also be an indication that the upstream process (mold, casting, etc.) needs to be altered to reduce excess raw material (reducing costs and scrap, etc.). At the very least, the excess stock can be accounted for in the shop’s schedule and in the lead time given to the customer.

Too little stock: This could mean the ideal finished part will not be realized from the supplied component, so the component should not be set up on the machine to avoid generating a scrapped part. It could also mean that the component must go through remediation before it can be post-processed. Either way, the parties involved have a heads-up on this condition and can make decisions without incurring further scrap or delays.

Re-alignment/re-layout: If the part analysis to CAD shows heavy in some areas and light in others, there may be an opportunity to save these components by digitally re-aligning the part to the CAD. Many available software packages (with varying degrees of ease and effectiveness) can digitally best-fit the collected part data to the finished CAD model. This can transform a part that was considered in failing condition and allow it to proceed through the value stream. The amount of data, and ultimately the 3D hardware/software solution, required to get a good part analysis to CAD will vary from part to part, based on geometry, complexity and tolerance. However, employing CAD data and 3D digitizing can be a fast, effective and almost error-proof solution for suppliers and downstream manufacturers.

Summary

As manufacturers continue to strive for nearer-net-shape molds, castings, forgings and fabrications of valves, this process becomes more detailed and subject to scrutiny. There could be dozens of complex inspection criteria (diameters, positions, angles, etc.) that must be satisfied before components are acceptable to the customer and viable for post-processing.

The speed, accuracy and quality of the data and its capture process with blue laser scanning and blue light laser scanning is supporting the throughput, efficiency and quality all along the manufacturing and production process. Operations no longer must wait for an end-of-the-line quality issue to investigate root cause and correct a costly issue. Rather, precision 3D information and data can be captured quickly, and thus earlier, to help drive corrections and make decisions.

Brad Browning is account manager at FARO Technologies. This article was adapted from a technical presentation Browning gave at VMA’s 2018 Valve Industry Knowledge Forum.