It is a passage in the mold that connects the nozzle of the injection molding machine to the runner or cavity. The top of the main flow channel is concave to connect with the nozzle. The diameter of the main channel inlet should be slightly larger than the diameter of the nozzle (0.8mm) to avoid overflow and to prevent the two from being blocked due to inaccurate connection. The inlet diameter depends on the size of the product, generally 4-8mm. The main channel diameter should be expanded inward at an angle of 3 degree to 5 degree to facilitate the demoulding of the runner excess.

It is a cavity located at the end of the main channel to capture the cold material generated between two injections at the end of the nozzle, thereby preventing the runner or gate from being blocked. If cold material is mixed into the mold cavity, internal stress will easily occur in the manufactured product. The diameter of the cold material cavity is about 8-10mm and the depth is 6mm. In order to facilitate demoulding, the bottom is often borne by a demoulding rod. The top of the demoulding rod should be designed in a zigzag hook shape or have a sunken groove so that the main channel debris can be pulled out smoothly during demoulding.

It is the channel connecting the main channel and each cavity in the multi-slot mold. In order for the molten material to fill each cavity at a constant speed, the runner arrangement on the mold should be symmetrical and equidistantly distributed. The shape and size of the runner cross section have an impact on the flow of plastic melt, product demoulding and the ease of mold manufacturing.

If we consider the flow of equal amounts of material, the flow channel with circular cross-section has the smallest resistance. However, because the specific surface of the cylindrical runner is small, it is unfavorable for the cooling of the runner extensions, and the runner must be opened on the two halves of the mold, which is labor-intensive and difficult to align.

Therefore, a trapezoidal or semicircular cross-section runner is often used, and is opened on half of the mold with a demoulding rod. The runner surface must be polished to reduce flow resistance and provide faster mold filling speed. The size of the runner depends on the type of plastic, the size and thickness of the product. For most thermoplastics, the cross-sectional width of the shunt is no more than 8m, the extra large can reach 10-12m, and the extra small can be 2-3m. On the premise of meeting the needs, the cross-sectional area should be reduced as much as possible to increase the redundancy of the shunt and extend the cooling time.

It is the channel that connects the main channel (or runner) and the cavity. The cross-sectional area of the channel can be equal to the main channel (or branch channel), but it is usually reduced. So it is the part with the smallest cross-sectional area in the entire flow channel system. The shape and size of the gate have a great influence on the quality of the product.

D. Facilitate the separation of products and flow channel system. The design of gate shape, size and location depends on the nature of the plastic, the size and structure of the product. Generally, the cross-sectional shape of the gate is rectangular or circular, and the cross-sectional area should be small and the length should be short. This is not only based on the above effects, but also because it is easier for a small gate to become larger, but it is difficult to reduce a large gate. The gate position should generally be selected where the product is thickest without affecting the appearance.

In order to ensure that the surface of plastic products is smooth, beautiful and easy to demould, all surfaces in contact with plastics must have a roughness Ra>0.32um and must be corrosion-resistant. Formed parts are generally heat treated to increase hardness and made of corrosion-resistant steel.

It is a groove-shaped air outlet opened in the mold to discharge the original gas and the gas brought in by the melt. When the molten material is injected into the mold cavity, the air originally existing in the mold cavity and the gas brought in by the melt must be discharged out of the mold through the exhaust port at the end of the material flow. Otherwise, the product will have pores, poor connections, and The mold filling is not satisfactory, and the accumulated air may even burn the product due to high temperature caused by compression.

Under normal circumstances, the exhaust hole can be located either at the end of the melt flow in the cavity or on the parting surface of the mold. The latter is to open a shallow groove with a depth of 0.03-0.2mm and a width of 1.5-6mm on one side of the die. During injection, a lot of molten material will not seep out of the vent hole, because the molten material will cool and solidify there and block the channel. The exhaust port must not be opened facing the operator to prevent the molten material from accidentally spraying out and injuring people. In addition, the matching gap between the ejector rod and the ejector hole, the matching gap between the ejector block and the stripping plate and the core can also be used to exhaust air.

It refers to the various parts that make up the mold structure, including: guide, demoulding, core pulling and parting parts. Such as front and rear plywood, front and rear buckle templates, pressure-bearing plates, pressure-bearing columns, guide columns, stripping plates, stripping rods and return rods, etc.

1. Guide parts

2. Launch organization
During the mold opening process, a push-out mechanism is required to push or pull out the plastic products and their condensate in the flow channel. Push out the fixed plate and push plate to hold the push rod. There is generally a reset rod fixed in the push rod, which resets the push plate when the moving and fixed molds are closed.

3. Side core pulling mechanism
Some plastic products with side concavities or side holes must be side-parted before being pushed out. After pulling out the lateral core, they can be smoothly demoulded. At this time, a side core-pulling mechanism needs to be installed in the mold.