Cable Tie Mold
Cable tie is produced by injection molding, for which the mold is one of the main significant factors.
Let us see the layout of cable ties, like the long leaves, with every piece attached to the central “tree and branches”.
The molten plastic ( PA66 / PA6 ) will run from the nozzle, sprue, main runner, sub-runner of the injection molding machine. And then it acrosses the cavity gate, cavities till the end of the cable tie tail. Most of this path is narrow and flat with lots of cavities.
PA66/PA6 is melted in the high temperature, around 260℃. In such path, the temperature will keep reducing and make the melt solidify. And that further builds the resistance against the forwarding of molten plastic.
Therefore, the mold temperature is always the main element that the mold maker and operator should consider. On the other hand, because the heat will accumulate with time, a cooling water runner is necessary as well.
Each cavity requests a ejector. But the dense ejector will affect the water runner’s layout.
Cost issue of the cable tie mold.
As we discuss above, cable tie is of various types ( different colors, sizes, designs ), so does the mold. It’s very necessary to keep the mold cost in a reasonable level. Otherwise, it will increase the cost of cable ties.
The main solution for that is to apply the standard parts as more as possible, especially for the inserts and the ejectors. Because the mass production of inserts and ejectors can be remained at a low cost. The main production place of these standard parts is LEQING, Zhejiang, the central cable tie production central.
Secondly, the same for the mold steel.
If you want the specially designed cable ties (including but not limited to the length and width of the cable tie), the cost will be higher.
Therefore, creating the cable ties with a special design wouldn’t be recommended. Or there will be lots of unexpected problems that you have to face.
Cold runner or Hot runner for the cable tie mold.
We generally call the hot runner mold for cable tie as semi-hot runner. There are normally 2 hot points for the runner, not one hot point per cavity.
Actually, the plastic melt is advancing from the injection molding machine nozzle to these hot points of the runner. And that will benefit the molding a lot, especially in the case of uneven raw materials and machines with wear and tear of different extent.
The mold temperature for cable tie injection molding is the key point. PA66/PA6 melt at a relatively high temperature with a great fluidty. At the same time, the high mold temperature will help the melt plastic run in a narrow space.
But if the temperature is too high, the plastic will degrade.
Besides, the fluidity and temperature are highly correlated. So the cable ties near the sprue part may easily produce flash, which is a common phenomenon. What’s worst, while flashes have been produced on one side, the other side near the farthest cavities is still in half filled situation.
Moreover, there’s another issue, that is, the design of each gate and the air exhaust way, to which we should pay much attention.
The mold test can reflect many problems. Hence, the mold must be tested and sample carefully studied by experienced professionals.
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