The type of gate of plastic injection mold

- Mar 15, 2018-

1. Disc-shaped gate: The material is extended along the outer circumference of the product. Its feeding point is symmetrical and the filling pattern is even, which can eliminate the bonding wire. Conducive to exhaust. The nozzle is often removed by punching and the punching process is designed. 

2. Fan-shaped gate: It gradually enlarges in a fan-shaped direction from the runner to the cavity. It is suitable for long or flat and thin products, reducing flow lines and directional stress. The fan angle is determined by the shape of the product. The cross-sectional area of the gate must not be greater than the cross-sectional area of the runner.

3. Ring gate: The glue is extended along the entire outer circumference of the product. It can make the plastic around the core evenly filled, and the exhaust is good, reducing the joint line. But it is difficult to remove the gate, it is suitable for thin-walled long tubular products.

4. Point gate: It is a gate with a small cross-sectional area, such as a needle. It is generally used for plastics with good flow. The gate length does not exceed its diameter. Therefore, the gate is automatically cut off after demolding and it is not necessary to modify it. The gate marks are not obvious. It is widely used in box cover, box shell and large-area products. It can add a mold surface to the mold to facilitate the water outlet stripping. The disadvantage is that it is easy to cause pressure loss due to the small size of the pouring gate, and some defects (flow marks, burnt spots, black spots) are formed during molding. The shapes are diamond, single-point, double-point, multi-point, etc.

5. Side gate: Generally set on the mold side, the mold surface from the inside or outside the plastic, cross-section mostly rectangular, suitable for a multi-cavity.

6. Direct gate: Directly from the main channel into the cavity, suitable for single-hole deep cavity shell, box-shaped mold. The flow path is short, the pressure loss is small, and it is beneficial to the exhaust, but the gate is inconvenient to remove, leaving obvious traces.

7. Latent gate: The gate is slanted on the parting surface side, and it can automatically cut off the pin gate when the product enters into the mold on the side or inside. It is suitable for automated production.

Design Points:  

1. The plastic inlet should be set in the thick portion of the product to ensure smooth and complete filling.  2. The location should be chosen so that the plastic filling process is the shortest place to reduce the pressure loss, which is conducive to the mold exhaust. 3. Through mold flow analysis or experience, it can be judged whether the product's joint line due to the gate location affects the appearance and function of the product. The cold spot can be added to solve the problem. 4. Avoid opening the gate near the elongated core to avoid material flow directly impacting the core, resulting in misalignment or bending of the deformation. 5. For large or flat products, it is recommended to use multiple points of pouring, which can prevent the product warping and lack of material. 6. Open as far as possible without affecting the appearance and function of the product, at the edge or at the bottom. 7. The gate size is determined by the product size, geometry, structure and type of plastic. It can take a small size and correct it according to the test mode. 8. In the case of multi-cavity molding, the same product adopts the symmetric pouring method. When the products are not molded in the same mold, the largest product will be placed close to the main channel.

9. In the cold material hole near the gate, set the puller as often as possible to facilitate the mold release.