Computer aided design (CAD) uses specialist software to create two- and three-dimensional images and animations of projects both in manufacturing and for use in advertising and technical manuals.
CAD can convey many types of information, including dimensions, types of material, and tolerances and is essential in offering solutions to both engineering and manufacturing problems.
Just as they use equations, drawings, calculators, pencil and paper, and experiments, mechanical engineers apply computer-aided engineering software in their everyday work of solving technical problems.
By creating and revising designs digitally and by simulating the performance of those designs virtually before hardware is ever built, engineers have greater confidence that their products will perform as expected.
In addition, design automation reduces the amount of routine work that an engineer must perform, so that efforts can be focused more on creative problem-solving.
By way of a case study, we highlight the role of computer-aided engineering tools during the design of a small but critical component of a product that is used during high-resolution medical imaging.
(i) System simulation:
As the syringe is inserted into the automated injection system, rotated, and snapped into place, the flanges on the syringe interface are subjected to large locking forces that could cause it to crack and break.
Using the CAD models, engineers analysed the stresses at the syringe interface and modified its design so that the flanges would be strong enough for its intended use.
The simulation predicted how the syringe interface would bend and distort as it is inserted into the injection system.
If the stress is too large, the engineers modify the component’s shape or dimensions until the design had sufficient mechanical strength.
(ii) Manufacturing process:
The CAD models were then used to support the manufacturing of the product.
On the basis of cost and required strength, the engineers decided that the syringe interface would be plastic, and that molten material would be injected at high pressure into a mild.
Once the plastic cooled and solidify-ed, the mild would be opened, and the finished part removed. The CAD models were then used to design the model; Figure depicts an exploded view of the mold’s final design.
The digital models enabled the designers to simulate the molten plastic flow into the hollow portions of the mold and to verify that it would fill as expected.
Engineers could then quickly adjust in the CAD models the locations of the seams, injection points, and holes where air could bleed out of the mold.
The results showed that air bubbles would not become trapped in the mold and the plastic would not cool and solidify before the mold became filled.
But if a simulation did reveal such problems, as illustrated in Figure, the engineers could change the mold’s design until the performance was satisfactory.