Digital manufacturing is the way of making things in which a product is first drawn, tested and planned in software, and only then cut, printed or moulded. A car, a phone, a refinery and the carton of a breakfast cereal are all made this way. The machine makes whatever the drawing says, so a mistake in the drawing becomes a mistake in every part.
The scene has three zones. CAD and PLM is the software that draws a product, tests it and keeps track of every version of every part. Process plant design does the same for a refinery or a chemical plant: how materials move through it, and where every pipe and vessel goes. On-demand manufacturing is where a finished design becomes real parts, made in ones or in thousands and ordered online.
Take, for example, an engineer at an auto-parts company in Pune who designs a new metal bracket. She draws it as a 3D model in computer-aided design (CAD) software. Then computer-aided manufacturing (CAM) software turns the model into a cutting program, and a CNC machine cuts the bracket from a block of steel. If she only needs one plastic sample, she can send the same model to a 3D printer instead. All the while, product lifecycle management (PLM) software records which version of the drawing was approved, and by whom.
Before computers, drawings were made on paper, and mistakes were often found only when the first parts reached the factory floor. By then, steel had been cut and tools had been made, so the mistake was expensive. Software moves the finding of mistakes to the screen, where fixing them costs very little.
A drawing gives exact sizes, but no machine can make a part with exactly those sizes. The difference that a part is allowed to have is called an engineering tolerance. A bracket whose hole is 0.3 mm too narrow may not fit its bolt. So each step of digital manufacturing must keep the same sizes from the screen to the machine. When one design record is carried unbroken from drawing to finished part, it is called a digital thread.
Design software is also some of the hardest software to replace. Engineers spend years learning one tool, and companies keep decades of drawings in it. So buyers rarely switch, which has made this one of the most profitable parts of the software industry. India builds a large share of it, with engineering centres in Pune, Bengaluru and Hyderabad.