Creating Complex Models with 3-D Scanning
GKS Inspection Services' RPS 150 Laser Probe
Ayotte Design Inc., a Newburyport, Massachusetts, provider of product and machine design services, had a manufacturing client that wanted to modify an existing plastic resin heart to demonstrate a new cardiac device. The medical device company required modifications on the model to fit the new product and then needed to manipulate it with computer-aided design (CAD) software to create the demonstration piece. The process presented several problems. "The heart model was a tricky, amorphic shape, which is difficult to scan with a contact process," says Gary Ayotte, president of Ayotte Designs. It also had an irregular internal, partially open cavity, the scan of which needed to be very accurate, as it would have to exactly fit the company's new device.
Ayotte contacted Larry Carlberg, a regional manager at GKS Inspection Services, a division of Laser Design Inc., to figure out how best to create the scan of the resin heart. GKS maintains several Laser Design scanners, so the appropriate size and resolution was readily available. Carlberg decided to use the RPS 150 Laser Probe for the project because it has an accuracy of better than 0.001 in. and made the post-scan modeling task easier.
Before starting the process, Carlberg explained how he planned to address the irregular surfaces of the model, as well as its internal cavity. He was able to provide examples of similar projects GKS had successfully completed and show the outstanding resulting image files.
Laser scanners quickly measure objects, record tens of thousands of points per second and generate huge numbers of data points without the need for templates or fixtures. Because the laser scanning system projects a line of laser light onto surfaces while cameras continuously triangulate the changing distance and profile of the laser line as it sweeps across the surface, the problems of missing data on an irregularly shaped or hollowed-out surface are eliminated. The RPS 150 laser probe system measured fine details of the heart model, capturing complex freeform geometry so that it could be exactly replicated. The most difficult challenge in scanning the heart model was the many small, venous features.
"We received the heart model with unnecessary items removed, but the intricate small features were still present on the model," Carlberg explains.
The Geomagic software provided with the Laser Design scanner greatly simplified the process of moving from the point cloud to the CAD model, making it possible to generate a CAD model of the scanned part that faithfully and quickly duplicated the original part.
"Even though Ayotte Design didn't feel we needed to replicate to the same level of feature detail, the modeling process demands we deal with the tiny surface abnormalities," explains Carlberg. "Otherwise the model would generate undesirable ripples on the surfaces. The surface model we generated with Geomagic Studio had outstanding replication of the plastic model that could not have been achieved by conventional modeling packages."
"The scan file of the heart model came back looking great," says Ayotte. "It was fully surfaced. We were able to import it cleanly into our CAD program, SolidWorks, without errors. The file came out really well, better than I expected."
Once imported into CAD, Ayotte Design was able to add the features the client wanted. Then the data were exported to create a rapid prototype stereolithography (SLA) model on which they could demonstrate their new cardiac device product to customers.
From the time Ayotte Design gave the model to GKS to the time the project was finished took two weeks.
The demonstrations Ayotte's client gave for its medical professional customers went very well. The improved heart model functioned perfectly with the new device, creating more business for the design client, as well as for Ayotte Design.
CAD image of a plastic resin heart, provided by the RPS 150 Laser Probe
GKS Inspection Services' RPS 150
- Accuracy of better than 0.001 in.
- Can accurately measure fine details on irregularly shaped objects
- Picks up tens of thousands of points per second
- Generates large numbers of data points without templates or fixtures