Snaps allow an easy method of assembly and disassembly of plastic parts. Snaps consist of a cantilever beam with a bump that deflects and snaps into a groove or a slot in the mating part. Snaps can have a uniform cross-section or a tapered cross section (with decreasing section height). The tapered cross-section results in [...]
Inserts are used in plastic parts, to allow the use of fasteners such as machine screws. The advantage of this is that since these inserts are made out of metal, they are robust. Further, machine threads also allow great many cycles of assembly and disassembly, Inserts are installed using one of the following methods. [...]
1) Incomplete Fillings: a) not enough resin to fill the mold completely b) inadequate injection stroke c) low injection rate d) low injection pressure e) resin viscosity too high f) exotic geometry […]
Living hinges are thin sections of plastic that connect two segments of a part to keep them together and allow the part to be opened and closed. Typically these are used in containers that are used in high volume applications such as toolboxes, fish tackle boxes, CD boxes etc. […]
1) Textures and Lettering can be molded on the surfaces, as an aesthetic aid or for incorporating identifying information, either for end users or factory. Texturing also helps hide surface defects such as knit lines, and other surface imperfections. The depth of texture or letters is somewhat limited, and extra draft needs to be provided [...]
1) Textures and Lettering can be molded on the surfaces, as an aesthetic aid or for incorporating identifying information, either for end users or factory. Texturing also helps hide surface defects such as knit lines, and other surface imperfections. The depth of texture or letters is somewhat limited, and extra draft needs to be provided [...]
Thick sections cool slower than thin sections. The thin section first solidifies, and the thick section is still not fully solidified. As the thick section cools, it shrinks and the material for the shrinkage comes only from the unsolidified areas, which are connected, to the already solidified thin section. […]
1) Drafts (or taper) in a mold, facilitates part removal from the mold. The amount of draft angle depends on the depth of the part in the mold, and its required end use function. […]
1) Sharp corners greatly increase the stress concentration. This high amount of stress concentration can often lead to failure of plastic parts. Sharp corners can come about in non-obvious places. Examples of this are a boss attached to a surface, or a strengthening rib. These corners need to be radiused just like all other corners. [...]
Bosses are used for the purpose of registration of mating parts or for attaching fasteners such as screws or accepting threaded inserts (molded-in, press-fitted, ultrasonically or thermally inserted). […]