Ribs, design considerations

Design Considerations for Injection Molded Parts (Parting lines, draft angles, wall thickness, fillets and radii, bosses, ribs, opening formations, shrinkage, gating, vents, potential knit lines)... 

In order to validate all the simulation results, a ribbed flat plate with different gate positions is conducted to examine the effect of fibers with various design consideration on injected parts both numerically and experimentally. Fmthermore, the warpage behavior affected by gate positions can also be examined fi om experiment and simulation results. 

The type of shelf design is the next consideration. The shelf can be a solid plate of plastic material, an inverted pan-like structure with reinforcing ribs, a sandwich-type structure with two skins and an expanded core, or even a lattice type sheet that has a series of openings. The choice between these is dictated by a number of factors. One is appearance or aesthetics. 

Preliminary consideration of candidate materials, processes and tooling factors, configuration, thicknesses in section, ribs, bosses, holes, surface characteristics, color, graphics, decoration, and assembly methods will begin to impose some discipline on the product design as it evolves. In the middle and latter phases of the design cycle, two or three concepts should make their validity apparent to all involved. With luck (logic), one will... 

The elimination of sharp inside radii is important to the design of ribs as well. For free-standing ribs, that raises a paradox in that it becomes difficult to provide generous radii at the base of the rib and still maintain the nominal wall rule of not increasing the wall thickness by more than 25%. The effect of changing the inside radii from 0.25W to 0.5W is demonstrated in Fig. 8.14. The 25% increase in wall thickness is represented by the circle which is 1.25W. In Fig. 8.14a, the radii at the base of the rib are 0.25W, and they are 0.5W in Fig. 8.146. Note how much thicker the rib is in Fig. 8.14a (Ti) than it is in Fig. 8.146 ( 2). There is a danger that the tip of the rib will become too thin when draft is taken into consideration 0.040 in should be regarded as a... 

Principal injection-molded parts considerations that influence processing conditions, machinery, and mold design include wall thickness, parting line and ejection, appearance, ribs, boss designs, holes and depressions, and corners, radii, and fillets [5]. 

Roof, Floor, Ribs, and Slopes To ensure the safety of workers in mines, effective design of underground mine entries, pillars, roof, floor and ribs must be incorporated using rock mechanics/ ground control analysis methods. Similarly, stable slopes must be designed for surface mines in consideration of geology, time, and anticipated conditions. 

Second, special considerations must be given to the design of flat areas to prevent bowing in the hollow shapes that are produced. Third, development of ribs or details off the surface can be problematical and can cause surface blemishes. 

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