8-cavity injection mold for the product „Drywall anchor”
( Design, manufacturing support and commissioning of a mold )
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Materials: PA ZYTEL 409
Guaranteed number of closing cycles: 1 000 000
Runner system: cold runner
Operating mode: automatic
The illustration on the right: was borrowed from the internet
A simple, standard construction. Not much else to say here. Oh, one noteworthy feature is the limit switch (blue) that monitors the return of the ejector plate. It’s used because the ejector of the injection molding machine is not rigidly connected to the mold’s ejector rod (at least not on the IMM
for which this mold was designed). In other words, it can only push forward. To retract the ejector system (if it’s not pulled back in time, the mold could be damaged), a spring (green) is installed. However, the spring can fail prematurely (for instance, due to a material defect). That’s why a limit switch is added -- when the ejector system fully returns, it signals to the injection molding machine “OK, all clear, you can close and start the next cycle” If no signal is received, the mold will not close.
Nowadays (actually, for quite some time), instead of one large spring, four smaller ones are used around the return pins. Return pins -- large, thick ejector pins that rest against the stationary half of the mold — also ensure reliable return of the ejector system. In some cases, like this one, they can’t fully prevent the issue by themselves.
Note: each cavity is fed through a tunnel gate, which allows the part to separate automatically from the runner during ejection. Therefore, the situation shown in the image -- a cluster of runners with anchors hanging from them -- is impossible in practice. It’s shown only for illustration
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