Ribs are used to:
- Increase the stiffness of a component.
- Add strength to a component.
- Assist in the production of a sound casting.
If the component in question is a structural part, careful consideration must be given to the design of ribs, especially in areas of high stress. Properly proportioned fillet radii must be used to avoid high stress concentrations at the junction of the rib and the main component. This can also assist in producing a sound casting by providing a means of distributing the metal. Current diecasting technology permits thinner and deeper ribs than were previously possible. However the ratio of width to depth does have a significant bearing on the design of the tool and the processes used to manufacture it.
The component designer should note that corners and edges at the parting line location must be sharp, which may be undesirable from the point of view of component service performance. All other locations should have fillet radii to avoid problems with early die failure, and promote better filling of the cavity.
In order to remove the casting from the die, movable ejector pins may be used. These generally result in a mark on the casting, and their location and size should be discussed with Dynacast as early as possible in the conception of the part. The marks left by the ejector pins can be raised or depressed - typically 0.3mm (0.012").
Necessary flash removal can be reduced by careful component design. Collaboration with Dynacast early in the design of components will result in more economical production.