Mold related system composition
The mold is composed of a number of related systems, which complement each other, so that the mold can be used normally. Common moulds include gating systems, ejection systems, core-pulling systems and other special designs.
One, parting surface
The die includes two parts on the side of the male and female die. The interface of the two parts is called the die parting surface, which has the function of die parting and exhaust. Due to the differences in the forming methods of different molds, it is easy to produce burring and knot, which affects the appearance and accuracy of the product, so we need to pay attention to the following content when choosing the parting surface:
1. Do not place it in an obvious position, so as not to affect the appearance of the product.
2. When opening the mold, the product should be left on the side of the demoulding mechanism.
3. For products with high coaxiality requirements, design the cavity on the same side as far as possible.
4. Avoid long core-pulling and consider placing it in the direction of opening mold.
5. Try not to use arc part parting, which will affect the appearance of the product.
6. For the plastics with good fluidity and easy overflow, the splitting method should be used to avoid the generation of raw edges.
7. If the mold is high and the demoulding inclination is small, in order to facilitate demoulding, it is recommended to divide the mold from the middle and divide the cavity into two sides.
Two, demoulding inclination
Release slope can help the product out of the mold, slope size according to the product shape, material, mold structure, surface accuracy and processing method design, generally 1-3 degrees, there is no exact value and formula, mostly in accordance with the empirical value. Without affecting the appearance and performance of the product, the larger the demoulding slope, the better.
Three, convex column
The convex column is the raised cylinder on the die product, which has the characteristics of strengthening the peripheral strength of the hole, assembling the hole, and increasing the local height. Convex column design should comply with the following:
1, its height to not more than two times of its own diameter is appropriate, otherwise it must be added reinforcement.
2, its position should not be too close to the corner or side wall, in order to facilitate processing.
3, preferred to choose round, to facilitate processing and material flow, such as at the bottom can be higher than the bottom surface 0.3-0.5mm.
Four, hole
Many injection molding products have holes, holes design method is as follows: directly on the product molding; First reserve holes in the product, and then complete with machine processing; After forming, it is drilled completely by machine. Hole design needs to pay attention to the following points:
1, the distance between the hole and the hole should be greater than or equal to 2 times the aperture.
2, the distance between the hole and the edge of the product should be greater than 3 times the aperture.
3, the distance between the hole and the side wall of the product should be 0.75 times more than the aperture.
