June 9, 2023How to better detect manufacturing defects See the article
Computer-aided design (CAD) is defined as the use of computers to assist in the creation, modification, or optimization of a design. CAD software enables designers and engineers to model shapes and add features with the ultimate goal of producing parts. The CAD process, however, is a closed digital procedure, meaning that all of the functions happen digitally inside the computer. But how do we get into this process, knowing that, of course, we cannot insert a physical object into a computer?
New parts can be designed entirely and directly in CAD software or they can be hand-sculpted using clay or other materials. Obsolete parts and damaged components must not be forgotten, as they often need to be updated, replaced, or fitted into a new assembly or environment. Thus, a bridge between the physical and the digital world is necessary to transition from an existing object to a CAD model. The process of converting a physical object into a virtual 3D model is called reverse engineering, and the bridge between worlds can be crossed thanks to 3D scanning.
When designing new products or adapting existing parts, engineers and designers like to use 3D scanners as a starting point for digitizing clay models or measuring physical objects in order to reconstruct their 3D models and integrate them into their designs.
But the role of 3D scanners does not stop at the design stage. They can be used throughout the entire product development process. After manufacturing, 3D scanning participates in quality control by checking that the part is accurate and conformed to the CAD model. Next, as parts are used, 3D scanning can reveal if there are deformations, showing engineers and designers where reinforcements, improvements, or variations should be added in the next version.
In this post, “3D Scanner for CAD” we want to guide you through the process of reverse engineering and demystify the process from a 3D scan to a CAD model. We also want to address the quality of 3D models generated with 3D scanners. Finally, we wish to help you choose the best 3D scanner and Scan-to-CAD software based on your needs and budget.
- 1 The Way to CAD
- 2 Selection of 3D Scanners and Scan-to-CAD Software
- 3 3D Scanners for CAD and Reverse Engineering
- 4 Ways from 3D Scan to Final CAD Model
- 5 Benefits of 3D Scanning for CAD Designers
The Way to CAD
Let’s say you have to replace a damaged component or update an obsolete part for which the original CAD model is nonexistent or inaccessible. So, you have to create a new CAD model for manufacturing. You can either start your CAD design from a blank canvas, which is likely to be a long, overwhelming iterative process, or you can leverage the data you already have from the existing object and use that information as a foundation for your design, which will make your work more accurate and effective. This avenue involves 3D scanning.
Here are the typical steps to create a virtual 3D model from an existing physical object:
- Obtain the 3D scan mesh (STL) by 3D scanning the part.
- Extract dimensional information, such as geometries, dimensions, and cross-sections.
- Import models into CAD software and proceed with CAD modeling.
- Compare the resulting CAD model (STEP or IGES) with the initial 3D scan mesh.
- Analyze feedback and use the comparison to optimize the CAD reverse modeling.
- Export the final CAD model of the part for manufacturing.
Can a 3D Scanner Directly Output a CAD model?
In short, the 3D scanner produces a mesh, or point cloud, which provides all of the needed dimensional information about the part’s surface geometry. This mesh can then serve as a template to sketch the new CAD model. CAD models are usually created using non-uniform rational basis spline (NURBS), which consists of points connected by curves, while 3D scans are typically exported as meshes, which are made of millions of small triangles.
Thus, a 3D scanner does not directly output a CAD model. An intermediate Scan-to-CAD modeling stage is necessary to bridge the gap and convert non-editable triangles into editable NURBS surfaces, with which you will be able to create a solid CAD model with editable features.
How Good are Generated 3D Models, and is Post-Treatment Required?
Based on your needs, there are different methodologies available to build a CAD model from an existing object. You may want to (1) reproduce a CAD model with accurate dimensions and precise angles to develop and manufacture new parts, or (2) reproduce an exact copy of a part (usually made of organic shapes) in its current condition. The first possibility creates a design intent and outputs a parametric model. The second option provides an as-is reproduction and outputs a surface model. Hybrid models also exist, which combine both methods for different areas of the object.
To get a parametric model from a 3D scan mesh, you first need to understand how the object was conceived. To do so, you must extract information from the scan data by creating entities, such as planes, cylinders, or cross-sections, on the mesh. These operations take place directly in Scan-to-CAD bridge software, such as VXModel. The parametric model and its entities can then be transferred to your preferred CAD software.
Similarly, to get a freeform surface model based on an optimized 3D scan mesh, you need to recreate the exact shape of a scanned object. To do so, you must improve and optimize the mesh by filling holes, smoothing surfaces, and trimming boundaries. Then, on the optimized mesh, you can create accurate freeform surfaces (NURBS) with control points. Again, all of these operations happen directly in the Scan-to-CAD bridge software before importing the freeform surface model into CAD software.
The 3D scanner does not generate NURBS surfaces (STEP or IGES) directly, but the Scan-to-CAD bridge software can. Nevertheless, the 3D models must then be imported into CAD software to get a parametric model for design intent.
Selection of 3D Scanners and Scan-to-CAD Software
Prior to choosing a 3D scanner and Scan-to-CAD software, you must identify your needs.
- What is the size of the part you want to scan?
- Is its geometry simple or complex?
- Can you easily move the part to the scanning session?
- What accuracy and level of detail do you need?
- What is your budget?
Do You Need a Stationary or Mobile 3D Scanner?
Stationary scanning systems are an option for limited budgets, but—as their name indicates—they require the part to be brought to the system, and they are mostly suitable for parts that are limited in size. Mobile scanners, which include both articulated arms and handheld scanners, are usually more accurate and better suited for large parts, and—as their name suggests—they go to the part rather than the other way around.
3D Scanners for CAD and Reverse Engineering
Creaform offers a variety of handheld 3D scanners, but three series stand out for product development and reverse engineering applications. Based on your budget and specific speed and accuracy requirements, a Creaform 3D scanner can certainly meet your needs.
The HandySCAN 3D|SILVER Series offers the best value for the money for technology innovators who wish to develop better products that are more suited to customer needs. This proven and trusted technology is accessible to low budgets and can shorten the development process.
The Go!SCAN SPARK offers the fastest and easiest 3D experience for product development, design, and reverse engineering. It enables the development of new products, with more complex shapes and designs, and gives a competitive edge by accelerating the time-to-market.
The HandySCAN 3D|BLACK Series is the most reliable and accurate ISO 17025-accredited portable 3D scanner available on the market. It can generate accurate 3D measurements and high-resolution results with the best scan quality.
Ways from 3D Scan to Final CAD Model
As previously mentioned, 3D scanning and CAD modeling are like two different subway lines that require 3D Scan-to-CAD software to connect them efficiently.
One avenue is to opt for complete reverse engineering (RE) software, such as Geomagic Design X, which offers high-performance functionalities for alignment, information extraction, and feature modeling. Complete RE software basically replaces CAD software for reverse engineering activities. In fact, it is a ”high-end solution” for designers who do RE on a daily/weekly basis. Consequently, designers who usually feel comfortable with their preferred CAD software must learn to use new software with different features. It is also more expensive than the other options.
Another way is to start the design from a blank canvas directly in CAD software without resorting to reverse engineering. CAD software is known to be designers’ favorite place for feature modeling, but developing a sketch from nothing can be a long and tedious journey. In addition, CAD software has limited functionalities for mesh editing, alignment, and information extraction from the mesh.
A more appealing approach is to choose Scan-to-CAD bridge software, such as Creaform’s VXmodel, which includes all of the functionalities to align, clean, and optimize the mesh as well as to extract dimensional properties before transferring the entities and cross-section into CAD software, such as SOLIDWORKS, Autodesk Inventor, and Solid Edge, where designers can comfortably proceed with feature modeling. This option is more appealing because it is less expensive than complete RE software; it is also simpler to use and easier to learn.
Benefits of 3D Scanning for CAD Designers
The benefits of using reverse engineering from Scan to CAD to create CAD models are important. It enables designers and engineers to create their 3D models from existing parts in less time, reduce the number of iterations leading to a part ready for manufacturing, and get a perfect fit of retrofit parts the first time. It can also shorten product development and time-to-market. But, more importantly, it provides an accurate foundation on which designers and engineers can build and improve their models—instead of starting from scratch—giving them more means to conceive complex geometries, modern shapes, and organic surfaces.
Scan-to-CAD bridge software is also ideal for CAD experts, as it is the shortest path back to your workflow and preferred CAD modeling software. Why learn completely new RE software when you’ve already mastered SOLIDWORKS, Autodesk Inventor, and Solid Edge?
In short, products designed through reverse engineering from Scan to CAD are not only of better quality, but also they are market-ready with fewer iterations and in less time. This is particularly valid for complex parts with intricate geometries. Creaform professional 3D scanners, such as the Go!SCAN SPARK, make reverse engineering more efficient, faster, and simpler. Scan-to-CAD bridge software, such as VXModel, leads you back to your preferred CAD software faster than any other solution, so you can get back to the joy of designing and innovating!