Parametric vs Direct vs synchronous CAD Modeling Techniques

Types of CAD Modeling Techniques

Following three types of CAD modeling techniques are widely used in the cad industry to create a 3D cad industry. Each of these three types of cad modeling techniques is different from each other and has its advantages, limitations, and applications.

  1. Parametric Cad Modeling
  2. Direct CAD Modeling
  3. Synchronous Modeling

Some engineers like the flexibility of Parametric Modeling. Whereas some engineers prefer how we create features in direct cad modeling without history. Most types of CAD software in the market either use a parametric or direct approach.

But some of the latest cad software are utilizing a hybrid approach known as Synchronous CAD Modeling. Synchronous cad modeling has features of both parametric and direct cad modeling combined.

Parametric CAD Modeling (History Based CAD)

Parametric CAD is also known as History based cad modeling. It is leading the pack in the CAD industry. Engineers like the flexibility of this approach. 

The history tree in the parametric CAD model contains all the information related to features, dimensions, constraints, relationships, assembly mates, etc. Users can modify features or dimensions. And the cad model will get updated on the fly.

Using the family table feature in parametric cad modeling similar designs can be generated by entering data in a table. For example, using parametric cad modeling and family table, you can generate M3 screw cad models in different lengths just by entering length data in a table. 

Parametric modeling has applications when engineers work on similar products and one design is dependent on another.

This image shows an example of Solidwork Parametric Modeling
Solidwork Parametric Modeling

But Sometimes, CAD model history becomes a problem for parametric cad designs. For example, any change in cad model features has an impact on all dependent features. Therefore any change in cad feature can break the cad model if the design intent is not correct.

Features of Parametric CAD Modeling:

Following are the features of the parametric cad modeling technique.

  • Dimension driven.
  • Structured CAD modeling.
  • Feature history.
  • Parent-child relationship.
  • Sketch constraints.
  • Part, assembly, and drawing modes.
  • Assembly mates.
Benefits of Parametric Modeling:

Using parametric cad modeling in cad designs has the following advantages.

  • Most parametric cad modeling software has basic direct cad modeling features as well.
  • Industry-specific parametric cad Software is also available.
  • Parts cad model is reusable.
  • CAD model indicates Product design intent.
Challenges with Parametric CAD

Following challenges come up while using parametric cad modeling.

  • Designers need to follow good modeling practices.
  • Long learning curve.
  • Difficult to modify dumb files (step/iges).
  • For large cad models, the feature regeneration process is slow.
  • For any modification in cad data. CAD users need to understand complete feature history.

Direct CAD Modeling (History Free CAD)

Engineers like the way direct modeling works. In direct modeling, features are created one on another without any history. For any design modification, the designer adds a new cad feature on top of existing features.

In this way, designers don’t need to worry about previous features. Therefore designers can create cad geometry very quickly and can focus more on innovation and creativity.

CREO DIRECT MODELING

Direct modeling also works best for dumb parts (step/iges) or where part design history is not available. Therefore direct cad modeling is popular during the initial design phase.

Parametric CAD Modeling Software
Following is the list of parametric cad modeling software:

  • Creo Parametric
  • Solidworks
  • Autodesk Inventor
  • Catia
  • Onshape
  • Fusion 360
    • Direct CAD Modeling Software
    Following is the list of direct cad modeling software.

  • Creo Direct
  • Creo Elements
  • KeyCreator
  • Rhino
    • Features of Direct CAD Modeling:
    • Flexible CAD Modeling Process.
    • Feature history is not available.
    • Direct Editing.
    • Parent-Child relationship is not available.
    • Parts and assemblies are created in one single mode.
    • Design Constraints and mates are not required.
    Benefits of Direct CAD Modeling:

    Following are the advantages of the direct cad modeling technique.

    • Any geometry can be created or edited.
    • It works best with native and dumb cad data.
    • Designers can concentrate on innovation and creativity because there is no need to plan for cad modeling.
    • Short learning curve.
    • Geometry editing is independent of how it is created.
    • Relatively smaller file size.
    Challenges of Direct CAD Modeling:

    Following are the limitations of using direct cad modeling.

    • Cad design automation is not possible.
    • Design intent from the cad model is not visible.
    • Can not use legacy data.
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    Synchronous CAD Modeling : Hybrid Approach

    Synchronous cad modeling is the integration of both direct and parametric modeling. It has the advantages of both parametric and direct modeling. This feature allows users to quickly modify CAD features and work effectively on imported CAD geometry.
    NX Synchronous Modeling

    In synchronous cad modeling, Industrial designers utilize direct modeling features to create designs and cad experts can create feature-based cad models for detail design.

    In this way, in synchronous cad modeling, both parametric and direct modeling features are used for product designs. Therefore the complete design process is more robust.

    Synchronous CAD Modeling Software
    Following is the list of Synchronous CAD Modeling softwares:

  • NX for Design
  • Solid Edge
    • Features of Synchronous CAD Modeling
    • Feature-Based and direct modeling.
    • Synchronous technology.
    • History is available.
    • Flexible editing.
    • Flexible editing in part and assembly mode.
    • Easy to use.

    Parametric Modeling vs Direct CAD Modeling

    Here is the list of the major difference between parametric, direct, and synchronous cad modeling software.

    ParameterParametric CAD ModelingDirect CAD Modeling
    CAD ModelingDimension Driven featured cad ModelingFeature Based CAD Modeling
    Part AssemblyAssembly Mates are used to assemble two or more parts.Parts are designed on top of another parts. Therefore assembly mates are not required.
    Feature HistoryAvailableNot Available
    Parent Child RelationshipYesNot Available
    Learning CurveDifficult to LearnEasy to Learn
    Software
  • Creo Parametric
  • Solidworks
  • Autodesk Inventor
  • Catia
  • Onshape
    		•
  • Creo Direct
  • Creo Elements
  • KeyCreator
  • Rhino

    • To sum up, both parametric and direct cad modeling techniques are used to create cad models. Synchronous CAD modeling is making its way to overcome the limitations of both approaches.

    For example, to design a consumer electronics product with A-Class surfaces. Designer design outer surface in direct cad modeling and detailed design using parametric cad software.  Don’t miss this article on the top 10 free cad software in 2020.

    We will keep updating more details on various types of cad modeling techniques. Add your suggestion or questions on different types of cad in the comment box.

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