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When designing plastic injection moulded parts to be used in conjunction with other parts, the assembly must be considered. There are several assembly techniques, mechanical fastening, press fit, hot staking, snap fit, welding, solvent bonding and adhesive bonding. We’ll cover each of these in more detail over the next two articles and how they fit into the design process.
When designing for plastic injection moulding, the aim is to reduce the overall number of parts for any given product. There are several advantages to this aim, not only will it reduce costs but it will make assembly easier. When designing, designers should lookout for any opportunities to simply the assembly process through a more efficient design.
Familiarity with assembly procedure
A thorough understanding of assembly drawings
Checking Parts
Mould Acceptance Technology
Developing Assembly Sites
Preparing mold standard parts and related materials
It might be hard to wrap your mind around at first, but many assemblies traditionally constructed of two unique components can often be made from a pair of identical parts.
But why not get rid of the screws altogether? Our gear housing example is now symmetrical, but it still requires manual installation of threaded inserts, never mind keeping track of all those pesky screws and washers.
Another way to achieve hero status is the use of family molds, which are ideal when producing a series of parts with similar shapes and sizes.
Everyone’s heard the adage about reinventing the wheel. Designing and manufacturing your own nuts, screws, shafts, pins, keys, and dozens of other off-the-shelf components should be avoided at all costs. Better to redesign your product around standard hardware items, especially if production volumes are expected to rise at some point.
The properties that make plastics such as polypropylene (PP) and styrene butadiene (SB) excellent candidates for living hinges.es of the chosen plastic are appropriate for the environment in which they’ll be used.
If a product must be assembled, attempt to make the task easier by orienting the various screws and connectors in such a way that all are accessible from the same side, thus minimizing part flipping and rotating.
