CAD/CAM: empowering manufacturing

Delcam’s managing director Vineet Seth explains why CAD/CAM is now an inseparable process amongst mainstream manufacturing
 Today, nearly everything that we touch, see and hear from is a product of the application of CAD/CAM and CNC technology. The cars we drive, the toys our children play with, the medical equipment that are used to diagnose or treat illnesses, the televisions we watch, the mobile phones we use, the computers that we work with, the chairs that we sit on, the spacecrafts that explore the universe and the planes we fly in are only a few examples of areas in which a part of it, or the entire product was created using CAD/CAM and CNC technology.
The history of CAD/CAM dates back to the early 1960s when various universities, large OEs and defence labs started using mainframe computers to create 2D views, analyse complex mathematical algorithms as well as create 2D NC tapes to run first generation CNC machines. It was only in the late 60s and early 70s that CAD and CAM received an integrated approach. Of course we have now come a long way from where things began, but the basics still remain true and form the foundation of most new technology.
Of course, the exponential increase in computing power has only added to the list of benefits to the CAD/CAM field, and as a result of this, we now see many possibilities with CAD and CAM which were earlier only theories on paper. Hybrid modelling, tribrid modelling, conversion of 2D images into 3D reliefs, reverse engineering, multi axis manufacturing, cad surface inspection, knowledge-based machining etc. are now a reality and are being put to use by many industries for their design, manufacturing and QA requirements. Hybrid modelling, which involves the design of solids and surfaces in a single environment, helps many tool & die and automotive companies create complex designs and parts rapidly. What used to take weeks earlier has now been reduced to days in terms of time spent in the design and manufacture of moulds and tools. By virtue of hybrid modelling, a designer can work concurrently in both surface modelling and solid modelling in any given model. Solid modelling assists in providing tools such as booleans, extrusions, revolutions; while surface modelling helps in addressing a specific surface within that solid for intricate options like spine, boundary, and UV curve editing.
This has not only increased the capability index of the limitless design possibilities but has also cut down drastically on lead times for designing as well as the process in whole. An extension of this, tribrid modelling comes with an additional capability of adding and editing triangles in the CAD environment. To give a brief idea of triangle modelling, let’s explain how exactly this is done. Let us imagine a golf ball, which has many convex depressions on the surface. If we were to draw lines from the centre of each of these depressions to the adjoining ones, we would see a network of triangles being created after we are done. This is what is known as “meshing” in CAD/CAM terminology. This is different from surface and solid modelling which are formed over “curves” rather than “points”. Tribrid and relief modelling, by means of a complex and high level “kernel” (the engine that runs the CAD/CAM software) allows CAD designers to “wrap” triangles onto surfaces and solids – which has been a major breakthrough for many packaging and signmaking industries across the globe. This allows designers to have 3D projections on surfaces which are extremely difficult and time consuming to design. By the help of relief modelling, a simple photographic image can be quickly converted into a 3D relief that can be mounted on to any CAD surface or solid. Many glassware and pet bottles we see today, that have 3-dimensional decorations are the result of the application of this technology. Tribrid modelling also allows for re-engineering of worn out parts quickly and efficiently, while being as close as possible to original dimensional accuracies.
Similarly, CAM too has now many options to offer, than it did earlier. From a pre-dominantly 2.5D manufacturing, we now see CAM addressing complex profile as well as multi-axis manufacturing. With the progress of the computer operating system, CAM programs which were generated on a non-GUI, moved to the new GUI, which gave the programmer many visual tools to analyse and work upon.  Many methods of manufacturing like turning, milling, grinding, wireEDM, Swiss turning, laser cutting, tape laying, punching are now programmed by CAM software. Unlike CAD, CAM needs a lot of information before hand to creating a NC program – which is the final product which is fed into the machine tool. Often, this pre-requisite data might not be available with novice users for a variety of reasons, and hence delays were a common reported issue.
Knowledge-based machining was a big boon to the CAM industry which overcame this barrier. Knowledge-based machining or KBM as it is often abbreviated, allows for standards to be pre-fed inside a database which is applied to a select operation. Standard data stored by KBM includes data pertaining to – cutting tools, material, machine data, post processor data, macros and sub-routines and strategies that are automatically applied to the current operation. This helps in optimising the toolpath even before it is run on the machine. You can imagine the amount of time-savings and accuracies this process brings. KBM is vastly acknowledged for added benefits to the 2.5D manufacturing process. However, when it comes to 3 Axis and beyond there exists a requirement of a little more than just KBM. CAD/CAM is driven by innovations. In the current age, everything is evolving rapidly, we see increased computing capabilities, machine tools, cutting tools, materials all are being innovated each day. The ability to machine components in the shortest possible time is an issue of ever increasing importance. Any development in engineering which can give faster delivery, and at the same time improve quality, must, therefore be given serious consideration.
Raceline machining, trochoidal machining, automatic trochoidal machining, rest roughing, constant Z, 3D offset finishing, optimised constant Z are a few HSM strategies for the roughing and finishing operations during milling.
Going further, 5-axis machining has been used in aerospace applications for many years but it is only recently that other industries like tool making, automotive, medical and dental, shoe and electronics industries have shown similar interest. The main advantage of 5-axis machining is the ability to save time by machining complex shapes in a single set-up. Additional benefit comes from allowing the use of shorter cutters that permit more accurate machining.
Positional 5-axis machining and continuous 5-axis machining are the two possibilities within this technology. Positional 5-axis machining allows creating 3-axis tool paths using different workplanes for alignment – thus requiring multiple setups, while continuous 5-axis machining allows the user to create continuous 5-axis tool paths across complex surface, solid and triangulated models, in a single setup.
Improvisations in multi-axis machining, such as port machining and blade/blisk/impeller machining have empowered the programmer to create efficient tool paths on complex profiles that are typical in high precision industries such as aerospace and automotive.
It is quite evident that there has been a tremendous amount of improvisation and innovation that has gone into the field of CAD/CAM. The reason why CAD/CAM is now an inseparable process amongst mainstream manufacturing is because it has never failed to evolve and innovate. Flexibility, scope, robustness, reliability, speed, efficacy, consistency and spectrum are all being worked upon continually to further improvise on existing features as well as create new features entirely. This innovation has kept CAD/CAM abreast of the latest in technology, adapting to new age manufacturing methods and encompassing ever increasing segments and applications.
Authored by__
Vineet Seth, Managing Director – India & Middle East, Delcam Plc, UKASEAN Business Development Director, Delcam Professional Services Ltd., UK

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