Out in the industry on shop floor, there are several machineries, tools and components that are in operation for years. So, necessarily their design drawings have been on paper since a long time. Such paper-based documented information is difficult to maintain over a long span since paper has the tendency to degrade with time. Also, for upgradation and changes of such machinery, today’s designers and R&D engineers need to study, edit and alter the design, which is possible only through digitized CAD models for quick and accurate results.

CAD Conversion

One of the approaches to digitization of drawings is creating CAD models of such large and complex machinery from scratch. But the problem with the approach is a time consuming process, engineers have resorted to CAD software. Inbuilt features of software have enabled designers and drafters to directly obtain CAD models from scanned data of the archaic paper drawings. Scanned data obtained through scanning of manual drawings or other pdf drawings is a raster image in non-editable form. It also has a very low resolution when enlarged. Thus, it becomes essential to convert raster images to vector images through AutoCAD, which are not affected by enlargement and easy to edit during later stages. Usually, the CAD conversion process is segregated broadly into two parts: Scanning and Modeling.

Scanning

Drawings of those components that need digitization of design, design alterations or features enhancement, are scanned through a high-quality scanner by a professional expert and are sent across to the design engineer for generating 3D CAD models. However, the scanning sounds simple, but handling of scanner and paper quality affects a lot on final output of point clouds scanned. Thus, it becomes necessary that the scanned data is readable for accurate CAD modeling. For optimum results, setting of scanner resolution, threshold and other features requires an expert. Modern scanners have a good setup, and are capable of file cleanup when done by a professional scanner.

Generating 3D Models

The scanned images obtained are in non-editable format, and another problem is it becomes difficult to interpret accurate geometrical information from it. These scanned files are raster images and essentially a cloud of pixels generating image, which when enlarged gets distorted. To remove such obstacles, CAD drafters import the images to CAD software and convert them to vector representation in the form of 3D CAD models. The automatic conversion process is not any simple; it requires accuracy in maintaining the spatial arrangement of each point on geometry of the component. However, researches are going on the issues related to raster to vector conversion.

Another hurdle that CAD drafters face is improper scan result due to poor paper drawing quality. For overcoming its effects on final CAD model, it requires drafters input to complete the process for pre-processing, clean-up, text extraction (OCR), line tracing, and shape recognition. The final CAD model is a vector drawing containing exact geometrical detail. These vector drawings are composed of lines and shapes that can be defined in mathematical equations and have accuracy even when enlarged. CAD drafters are capable to generate the models as per requirement in any standard dimensioning system namely ASME – American Society of Mechanical Engineers, BS – British Standards and ANSI – American National Standard Institute.

Even though the process involves very high accuracy throughout, there are instance where engineers have successfully accomplished it. The pdf drawings of a reducer gear assembly were converted to CAD models for a Customized Tools & Equipment Manufacturer in India. Engineers using SolidWorks developed CAD models describing manufacturing assemblies and Bill of Materials – BOM. The information was further enhanced in generating 3D CAD solid models for assembly purposes. The manufacturer was benefited with editable CAD files and details for fabrication process.

Conclusion

No matter how much accuracy the process demands, digitization of component design is essential. CAD allows easy migration of design data into editable CAD files for better returns. Design engineers need to have 3D CAD models to study and change the design for upgradation and uplifting the position of product in the markets. Safety tests can also be performed in a virtual environment, if 3D CAD models are readily available.