Getting to Know PADT: Part Scanning and Reverse Engineering

This is the first installment in our review of all the different products and services PADT offers our customers. As we add more, they will be available here.  As always, if you have any questions don’t hesitate to reach out to info@padtinc.com or give us a call at 1-800-293-PADT.

Product innovation doesn’t always start with a blank sheet. Many times our customers need to begin with an accurate representation of their existing products, or a piece that theirs interfaces with, or even a competitive solutions.  That is why we offer scanning and reverse engineering services that take real world parts and convert them into an accurate and useful CAD model.

What is Part Scanning

Part scanning is a process where we use machines to measure geometry.  Before scanning someone would use rulers, calipers, and other measuring devices dating from the industrial revolution to get critical dimensions off of a part and painstakingly document what they find. That got better with Coordinate Measuring Machines (CMM) where you could accurately measure key locations on the geometry. The problem with this approach was that it only gave you data where you measured.  Fine for simple parts like a flange with bolt holes.  But not good when you have crazy free-form surfaces or many features. Another approach was to section the parts and project a shadow onto a piece of paper and trace it.  If you needed more measurements, cost went way up.

To solve this problem, people found a way to measure lots of points easily: scan the part with some sort of optical sensor and measure points on the part as you go.  Early scanning systems used lasers, measuring the beam that bounced back.  This worked well, especially for very large objects.  But was tricky on some surfaces and produced a lot of noise in the data. So researches figured out that they could project patterns of light and dark onto an object and measure how the edges of that pattern bent and warped.   This is called Structured Light Scanning, and Wikipedia has a good article giving more details on how it works. We use the “blue light” version of this process here at PADT for our optical scanning services.

The other process we use is Cross Sectional Scanning. As the name implies it scans the cross section of parts, and it does it by actually shaving off material one layer at a time and then taking a picture of the 2D cross section that is revealed.  Although you consume the part in the process, it is a very accurate and fairly affordable way to measure complex internal geometry.

What you get from both scanning approaches is what we call a point cloud.  What is a point cloud? A file with millions of points defined as an X, Y, and Z position in space that represent locations that sit on the surfaces of the object.  You can measure critical dimensions, compare different geometries, and use it as a basis to create a computer model.  The key thing to note is that PADT uses precise scanners and leading software, combined with the experience of our operators to produce an accurate and usable point cloud.

Creating Accurate Models from Scan Data – Reverse Engineering

For most projects, getting the point cloud is just the first step. In order for our customers to redesign, update, simulate, or interface with the part we scanned, they need an accurate computer model.  Instead of millions of points, the computer model contains a more concise mathematical representation of the surface defined by the points. The simplest thing we can do is simply fit triangles through those points.  This is refered to as a faceted model because it is made up of triangular facets.  This data is used for 3D Printing, rendering, and for design in some cases.  Most often we deliver an STL file for this type of model. If a more accurate representation is needed, our engineers can convert those facets into an actual Computer Aided Design (CAD) model.  It can be just a dumb solid, or we can even make key features parametric.  The geometry can be handed over in many different formats, including IGES, Paraolids, STEP, SolidWorks, SolidEdge, NX, or CREO.

How Part Scanning with PADT Different

To be blunt, the reason why we added scanning to our capabilities was that we had always outsourced this service for our customers.  We found plenty of people with scanners, but they just scanned a part, ran the software, and provided OK data for our customers.  The problem was they were not experts in the technology behind scanning, they lacked a theoretical understanding of math behind 3D computer geometry modeling, and they were not experts in product development.  It turned out that scanning the geometry was the easy part, what our customers needed was someone who knew how to scan it right and produce useful information.  Information they didn’t have to spend time cleaning and massaging. Our engineers combine all of these skills along with a firm understanding of quality requirements, GD&T, and most of the major CAD systems.  In addition, PADT is ITAR compliant and can deal with your confidential geometry and data requirements.  The fact that PADT is a recognized expert in Additive Manufacturing is often useful as well.  We could not find a service provider that had all of the things our customers required, so we decided to do it ourselves.

Leveraging PADT’s Part Scanning and Reverse Engineering Services

Getting parts scanned by PADT is actually fairly easy.  Step one is to contact PADT and talk to our engineers so they can produce a quote.  Ideally it is best for you to bring the part or parts in to our Tempe office. If that is not feasible we will need some basic pictures of your part and key dimensions like maximum length, width, and height. They will then talk with you to understand what you actually want to accomplish by scanning.  Armed with this information they will provide a quote for scanning and any geometry creation or other activities you need completed including cost, schedule, and a list of deliverables.

In  most cases, you will ship us or drop off the part or parts, and our team will go to work.  If needed, we can also come to where the parts are located and scan them there.  The deliverables vary from job to job, and are negotiated as part of the quoting process.  In general we will provide you with an STL or CAD file with the level of accuracy and detail that you ask for. If needed, we can also provide you with the point cloud  itself.  We can also complete inspection reports and provide comparisons between datasets.

Reach out to Give it a Try or Learn More

Our team is ready and waiting to answer your questions or provide you with a quote.  You can email us at info@padtinc.com or give us a call at 480.813.4884 or 1-800-293-PADT.

Still want to learn more? Here are some links to more information:

  • Download or scanning brochure
  • A more detailed blog post on scanning from early 2017, including a “Scanning 101” section with some great background on the technology
  • The 3D Scanning Wikipedia article.  This has lots of basic information as well as more links to greater details.
  • Information on the Geomagic Capture Scanner, an easy to use, compact, and very portable blue light scanner that we use for a lot of projects.
  • Details about the ZIESS Comet optical scanner, a professional and highly accurate blue light scanner that we use for our more demanding projects.
  • An overview of Cross Sectional scanning.
  • A brief summary of the Geomagic Software we use to create useful models from point clouds. It also has links to more in-depth information.
  • An article in Additive Manufacturing magazine about how PADT used our scanners to create a replacement part for a P-51 Mustang airplane.  It includes a great video as well.