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AutoCAD Drafting India/Articles/2D Drawings & 3D CAD Models offer same Accuracy to Design Engineers; then why latter is preferred?

2D Drawings & 3D CAD Models offer same Accuracy to Design Engineers; then why latter is preferred?

Posted by on December 19th, 2016

2D Drawings 3D CAD Models

3D CAD modeling have grabbed so much of attention that design engineers have relied upon 3d models for technical works in several disciplines related to component designing and post design drafting processes like analysis and understanding of manufacturing assembly drawings. It was easy for a design engineer and drafter to understand 2D drawings pretty well. So, then why go extra length and generate 3D CAD models when designers already have 2D drawings in computers and possessing the same accuracy?

For one reason, only the engineers understood them with clarity and buyers, salesman & suppliers who lacked the mastery of technical knowledge failed.

A comparison between 2D CAD Drawings and 3D CAD Models

2D CAD drawings generated using CAD software is just same as traditional 2D drafting with drawing sheets and pencils. The only difference is that a CAD generated drawing is more accurate in terms of dimensioning and changes can be done easily. But these same 2D CAD drawings when compared against 3D CAD models, are less reliable and do not serve the design intent as fairly as the later. 2D drawings depict only length and breadth of the component and thus any feature is represented by horizontal and vertical lines with curves and arrows. Provision for depth or thickness is not an inclusion. The third dimension of visualizing drawing and component’s exact design is then left to engineers and project stakeholders based on their individual capacity.

But with 3D CAD models, the added third dimension of depth or thickness leads to better understanding and explanation of design intent. 3D modeling allows designer and drafter to draw in any angle on a 2D computer screen with a better perception of products parts. It shows how the built product will exactly look like.

Better Understanding with Enhanced Features of 3D Model

Once 3D models are generated, final images and models of the component are rendered. Rendering leads to crystal clear understanding of what the product will look like, with surfaces having shadows and lights variation. Rendered images are just images taken from CAD software and are edited for photorealistic finish.

Below is a drawing, a model of recycling plant generated with CAD software. We want you to list the components of this assembly drawing that are understandable with its name and functions. How good is this? Not much, right? Now see the next figure, it is the same model, but with rendered qualities and enhanced features of each pipe, and its network of interrelation with other connecting pipes. Moreover, concentrate on the major network of pipes. Which one has a better depiction and communicates with you in a better manner?

Off course it is the second one; the rendered image. Rendering is not possible with 2D drawing although generated using CAD software. Such rendered image can further be employed for animation videos creation and presentation.

Recycling Plant 2D Drawing

Recycling Plant CAD Model

Making any change in the design is easy with 3D CAD models. One change accommodates the change in the entire model, and when the different views of assembly are taken, software shows the updated views. Alongside, in case of parametric modeling, change in one design parameter, the software will take care of successive interdependent changes, termed as modifiability.

In addition to this, 3D models are necessary for analysis of component and validation of design safety in a virtual environment using software like ANSYS. With virtual application of load, pressure and stresses and material of component as inputs, the software shows resulting changes in component body. Finite Element Analysis – FEA results suggest design changes to the design engineer which can easily be incorporated in the model through dimension alterations, modification of material and other aspects.

Other Benefits

  • Apart from design procedure, 3D CAD models have led to design automation and reducing the product development time. It accelerates the product cycle since most of the design optimization is done through software interface.
  • Once the designs of standard part are created and certified by suppliers or manufacturers, they are stored in 3D parts catalogs, which can be retrieved and used whenever needed for assembly models.
  • Rapid prototyping feature of software allows reducing the time for prototype parts and generates Bill of Materials – BOM through assembly drawings.
  • CNC programming simulation helps in CAM – Computer Aided Manufacturing and program generation for precision manufacturing of critical parts.


With all the advantages of 3D CAD models in pre and post designing phase, engineers are naturally attracted towards their use, dumping 2D CAD drawings mid ways on their journey of innovation, accuracy, rapid transit from conceptualization to reality and quality clubbed with efficient product delivery.


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