A profound understanding of injection mold processing

For plastics with good fluidity and easy overflow during injection mold processing, the insert breakage method should be selected according to the type to prevent the generation of burrs. For products with high height and low demolding slope, center parting can be used, and the mold cavity can be divided into two ends for easy demolding. In order to make the product easily come out of the mold, it is necessary to set the demolding slope on the mold, which depends on the shape of the product.

The plastic processed by injection molds has different mold structures, surface accuracy, and processing methods, usually 1-3. The greater the demolding slope, the better, without affecting the appearance and performance of the product. The diversion channel is the connecting part of the main channel, located between the main channel and the gate, and has the functions of diversion and turning. The diversion channel needs to transport the molten plastic to the sprue for mold filling at a faster speed with minimal pressure loss.

The circumference of the square processed by injection molding is long and the circle is short. If the area is too small, it will reduce the plastic flow rate, prolong the filling time, and easily cause product shortage, paste, silver wire, and shrinkage; If it is too large, it is easy to accumulate too much gas, increase cold materials, prolong production cycles, and reduce production power. Different plastic materials have different diversion channels.

 But there is a planning principle for injection mold processing: it is necessary to ensure that the ratio of the surface area to the volume of the branch channel is small, that is, when the length of the branch channel remains constant, the ratio of the surface area or lateral area to the cross-sectional area of the branch channel is small. There are many types of diversion that vary with different plastics and mold structures. Common types include circle, semicircle, rectangle, trapezoid, U-shape, and regular hexagon.

The basic principles of injection mold processing planning:

When conditions permit, the cross-sectional area and length of the splitter should be as small as possible.

When the diversion pipe is long, a cold material chamber should be set at the end to accommodate the cold material and prevent air from entering. A pulling rod is usually installed on the cold material chamber to facilitate the demolding of the rubber channel.

In multi cavity molds, the distribution channels should be as consistent as possible and the length should be as short as possible. The cross-sectional area of the main channel should be greater than the sum of the cross-sectional areas of the diversion channels.

4. Its surface does not need to be too smooth (Ra=about 1.6), which is beneficial for insulation.

 5. If there is a lot of diversion, extra flow cones should be considered to prevent molten plastic from directly impacting the mold cavity and to prevent plastic from making sharp turns, ensuring a smooth transition of the plastic.

 6. The wheel is generally distributed using the balanced method, and in special cases, the unbalanced method may be used. All cavities require balanced filling with glue, compact layout, and short process to reduce mold size.

 When planning the flow channel for injection mold processing, a smaller proportion should be used first to provide a correction margin after mold testing.