The Four Levels of CAD Model Quality

Selling parts to engineers can be tricky when you’re not an engineer yourself. It’s a complicated field with a lot of specific terminology, and you’ll want your parts to satisfy your engineering customers’ needs. This starts with understanding the different levels of computer-aided design (CAD) models you can use for your parts and the benefits of each.

Level 1 – 2D Drawings

Long before computers existed, engineers used 2D drawings to plan engineering projects. In the past, engineers used drawings to design entire systems, as well as the individual parts that made up the system. They traditionally used these drawings for manufacturing purposes.

Today, 2D drawings perform the same functions. Engineers primarily use them to show what a part looks like and how it functions for manufacturing, and they include dimensions and other relevant manufacturing information.

Engineers still use 2D drawings today, but 2D drawings are quickly becoming a relic of the past. Although useful in specific situations, they’re limited for use in modern manufacturing automation and connected engineering systems. Until recently, nearly all 3D models created in CAD programs were converted into 2D drawings for use in the manufacturing process. This practice is slowly dying as more CAD models include all the necessary information for manufacturing.

Level 2 – Neutral CAD formats

Neutral CAD formats (STEP, JT, etc.) are the most common formats that industrial manufacturers and suppliers provide to engineers. Most engineers can utilize neutral formats no matter what software they work in, and these formats play an important role in processes downstream from engineering. For example, an engineer can use a neutral file format to share geometric information with a partner that is designing a mating component. Organizations can also use neutral formats to translate CAD models into manufacturing formats.

Neutral formats were once seen as the future of CAD because of their versatility in many CAD systems, but they don’t carry and deliver all of the necessary data for downstream processes, and they lack the data required for new technologies like machine simulations and automation. Neutral formats also have severe limitations when applied to Industry 4.0 technologies like IIoT, digital twins (see Level 4), and factory automation.

These formats are still ideal when an organization needs to share key geometry characteristics without divulging full IP design intent, or when engineers need to archive models to ensure the models are available in future versions or different systems.

Level 3 – Native CAD formats

Native CAD formats (from CAD software like CREO, Catia, SolidWorks, etc.) are the default file formats that a CAD program uses to save designs. Native CAD files have detailed information like dimensions, mates, constraints, and other data necessary for a cohesive design. It’s best to use native CAD formats whenever possible and to only translate files into a neutral format when absolutely necessary. This ensures team members lose little to no data when transferring files.

Although native CAD files contain detailed information, not every individual or group uses the same CAD software, which limits full access to data and information for some people in the product life cycle. For example, if an engineer creates models in NX and their manufacturer uses SolidWorks, the manufacturer may have difficulty opening the engineer’s files or accessing all the necessary data.

It’s easy to associate native CAD formats with your company’s internal parts and designs; however, it’s just as important to use native CAD models from suppliers. Typically, suppliers offer only neutral CAD formats – and possibly one native CAD format – for the parts they sell. Some suppliers understand that engineers need data only accessible through native CAD models, and these suppliers offer many different formats to give engineers the maximum value for products.

Level 4 – Component Digital Twins

Component digital twins are native CAD models with high-quality “ingredients.” They’re digital replicas of physical parts that contain specific information such as design intent, motion data like kinematic information, and data to drive Industry 4.0 technology.

Component digital twins have vital and accurate CAD metadata and other attributes for IIoT, industrial automation, and connected systems. When models have accurate data, they can drive simulations and downstream processes like machine automation and predictive maintenance. This means engineers can make design decisions much earlier in the process or use the data to predict future needs, which saves time and money. To learn more about component digital twins, watch the free webinar.


Which is best?

So which CAD model is best? Every expert has a different opinion, but in the end, it all depends on context. Who/what is the model for? What information must viewers have to use it? In general, choose a CAD model based on:

  • The capabilities of the supplier and OEM to generate the necessary info for each other.
  • The ability to access parametric and historical modeling data in perpetuity.
  • The level of metadata required to drive downstream processes.
  • The desired mathematical accuracy.

Which is Better?

Native CAD or Neutral CAD?

The debate rages on about which is the best format to use. What CAD formats are superior. Six industry experts weigh in to decide.

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Kelly Obbie

Social Media Coordinator at CADENAS PARTsolutions | A 2018 graduate of The Media School at Indiana University, Kelly studied journalism, public relations, English and Spanish and has experience in news writing and editing as well as social media writing and management. She also has professional and personal experience in videography and photography. She currently lives in Ohio but has lived in four states, and in her free time, she enjoys running, hiking, learning languages, and watching Disney movies.