Updated: Feb 28, 2018
Engineering drawings provide graphical representations of physical objects and concepts with detailed dimensions, cross sections, annotations and notes. Drawings allow manufacturers to understand how a product is to be made by defining features, dimensions and tolerances. In essence, it is a form of communicating the design intent from a digital mock-up to a manufacturer.
Generating 2D drawings used to be a task for a skilled draftsman, able to visualise and sketch products on paper, organising views before drawing them followed by adding notes, dimensions, tolerances and datums. If a draftsman made a mistake on paper, for example not leaving enough room to accommodate views or dimensions, they would often have to start again. However, when CAD began to be used for drafting, these skills were no longer as essential due to the software creating a digital mock-up and drawing much easier and quicker, removing the penalties of making mistakes and introducing more accurate methods of dimensioning and tolerancing from CAD models. The days of a skilled draftsman are gone and now all engineers should be able to generate 2D drawings from 3D models effortlessly as well as being able to interpret the information represented on technical drawings.
Engineers still need to know the correct drawing standards to work to however, such as BS 8888 in the UK and ISO 8015 in the US. This standard may differ depending on company as well as country. Additionally, Geometric Dimensioning and Tolerancing also has its own standards and varies depending on whether you are based in the UK, USA, Europe or Japan, however, they are all sub standards created from the ISO standard. Having common standards allows for more effective communication between vendors and suppliers, reduces the number of errors on drawings which increases efficiency and helps simplify product development processes.
Today many companies are shifting towards 3D drawings, meaning adding the same annotations and dimensioning to a 3D CAD model. 3D drawings are easier to understand since you are able to manipulate the model by moving it around to understand and examine exactly where the measurements are taken. Additionally, utilising dimensioning, notes, tolerances and datums within a 3D environment reduces to total number of files, which if you are a very large OEM, can make a large financial and data management difference. There are now also 3D CAD drawing standards such as ASME (American Society of Mechanical Engineers) Y14.41 which provide the best practices for applying GD&T (General Dimensioning & Tolerancing) to a model. Not only individual companies but certain industries have completely migrated across to 3D drawings. In the aerospace industry 3D Functional Tolerancing and Annotation has become an industry standard and all suppliers are required to be able to create or read these drawings. To be able to read a 3D annotated drawing, you must either have a 3D PDF, STEP File or a JT file showing the 3D PMI (Product and Manufacturing Information).
However 2D drawings are still commonly used across many industries. Sometimes this is as well as 3D drawings as they are universally accessible as PDFs or paper documents. 3D drawings require the viewers to have the correct CAD software and specific licenses to edit them which involves a high start up cost and is not as easy to use as most drafting workbenches in various CAD packages. Perhaps 3D PDF’s and other common viewing software will be utilised more in the future and help eliminate this issue. One area that may not be able to eliminate 2D drawings, is smaller suppliers who do not have the set up or necessary software to be able to read such documents. These smaller suppliers, if they cannot keep up with the industry standard will be eliminated throughout the bidding process of a project. The fact that there is the potential to lose small businesses from the engineering supply chain market is concerning as it could end up creating monopolies in certain sectors of engineering and reducing supplier competitiveness.
In the interests of saving time, money and data management on generating and managing 2D drawings, I believe they will become a practice of the past. Many companies are slowly grasping the concepts of efficient 3D drawing processes and I believe as more users and companies move forward with this, the CAD tools available will become increasingly more powerful and easier to use.
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