Points to note when designing plastic molds

There are two templates on the injection molding machine, one is not moving, called the fixed template; the other can be moved, called the moving template. The plastic molds are respectively fixed on the two templates by screws and pressing plates. When the mold is opened, the movable template of the injection molding machine moves, thereby driving the mold to open.

After the plastic mold is manufactured, it is necessary to carry out injection molding, put on the injection molding machine, and start to produce products. However, there are many models of injection molding machines, and each injection molding machine has its own parameters. The design mold must be able to meet the requirements of the injection molding machine model provided by the customer, otherwise it will not be able to produce. There are many design parameters of the injection molding machine, and I will focus on several parameters related to the mold.

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1. Injection volume: The injection volume is the maximum mass value (or volume value) that the injection molding machine can shoot at one time during production, and represents the maximum injection capacity of this type of injection molding machine. The amount of melt used in the designed mold is less than the injection volume of the injection molding machine. Otherwise, the product is dissatisfied and cannot be produced.

2. Clamping force: It is the pressing force of the injection molding machine on the template when the mold is closed. The clamping force required for the molded product during molding must be less than the rated clamping force of the selected injection molding machine. Otherwise, the molten glue will easily run off the parting surface, resulting in flash.

3. Tie rod spacing: There are four tie rods in the dead corners of the fixed template and the movable template of the injection molding machine. Their function is to ensure that the injection molding machine has sufficient strength and rigidity, and is responsible for sliding the template. However, it tends to limit the overall dimensions of the mold, because the plastic mold is hoisted in from the middle of the tie rod when it is installed.

Mold dimensions cannot be greater than the distance between the tie rods for them at the same time. If the length of the mold exceeds the distance between tie rods, check whether the mold is hoisted into the tie rod workshop by rotating. If the rotary hoisting cannot be carried out, then the mold size can only be changed. , Or replace the injection molding machine.

4. Nozzle size check: The nozzle head of the injection molding machine is generally spherical. When selecting the sprue sleeve, the spherical radius of the sprue sleeve should be consistent with the spherical radius of the nozzle. In order to prevent the high pressure melt from overflowing from the contact gap between the nozzle and the sprue bushing, the spherical radius of the sprue bushing should generally be larger than that of the nozzle. At the same time, the size of the small end of the main runner should also be slightly larger than the size of the nozzle hole. Easy to align the muzzle.

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Post time: May-21-2021