In injection molding, molten plastic is poured into a mold to make a product.
Generally, as many molds are needed as the number of products. For example, a product consisting of four parts requires four molds.
It is difficult to make four molds, and each mold must be injection-molded four times.
Injection molding must be done a total of four times, once for each part. That is a lot of work.
How can we do all of this in one go? One answer is
One way to answer this question is to use a single mold for four products.
In the molding industry, this is also called a set-top mold or a family mold.
With this configuration, only one injection molding is needed.
The key to this configuration is the design of the runners and gates that successfully pour the plastic into the product.
Runner ： A thin bar that surrounds the product.
Gate ： The part where the product and the runner are connected.
The runner is the first path the melted plastic will take.
If this path is not branched well, the plastic will cool and harden along the way.
The gate is where the runner connects to the product.
The thicker the gate, the better the plastic flows into the product, but the more difficult it is to separate the gate from the product.
The narrower the gate, the easier post-processing becomes, but the plastic does not flow easily, and filling defects are more likely to occur.
However, it is more difficult for the plastic to flow through the gate, and filling defects are more likely to occur.
Therefore, designers design gates that are thick enough to achieve both ease of molding and ease of operation.
Plastic models, for example, have many products on a single runner, but they are arranged for ease of production and productivity.
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