company news about This article thoroughly explains the core logic of injection molds.

The "organs" of the mold: These 5 parts cannot be missing any one of them.

1. Molds and cores: The "appearance" of the product comes from here.
This is the "core of the core" of the mold: 
Cavity: It is responsible for the "outer surface" of the product, such as the curved surface of a plastic cup or the exterior surface of a mobile phone case. All these are determined by the cavity;
Core: It is responsible for the "internal structure" of the product, such as the hollow part of a plastic cup or the threaded holes on parts. These are all "pushed out" by the core.
The precision of the cavity and the core directly determines the precision of the product. For example, when making a 5G connector, the spacing of the pin slots in the cavity needs to be controlled within ±0.005mm; otherwise, the pins in the finished product will not be able to fit in. If there is a 0.01mm scratch on the surface of the cavity, there will be a obvious defect on the finished product, and it will be directly scrapped.

2. Pouring System: The "pipeline" for transporting plastic

The melted plastic needs to be sent into the mold cavity through the pouring system, which is like the "blood vessels" of the mold. It mainly consists of three parts: 
Main channel: Directly connected to the nozzle of the injection machine, it is the "first gate" for the plastic to enter the mold;
Diversion channel: Divides the plastic from the main channel into multiple cavities (for example, in a bottle cap mold with 32 cavities, the diversion channel is needed to evenly distribute the material);
Gate: The "last checkpoint" for the plastic to enter the cavity. The size should be just right - too large may cause marks, and too small may result in insufficient plastic filling.
I once encountered a problem: In the production of parts using multi-cavity molds, some were complete while others were incomplete. Later, it was discovered that the thickness of the diversion channels was different, causing the plastic not to be evenly distributed. Later, I changed the diversion channels to the same thickness, and the problem was immediately solved.

3. Cooling System: The "Cooling Magic" Made of Plastic

After the melted plastic is poured into the mold cavity, it needs to be rapidly cooled and solidified by the cooling system. Otherwise, the product will deform and have blemishes. The cooling system is the water channels drilled inside the mold. There are two key points: 
Close to the cavity: The water channels should be 8-12mm away from the surface of the cavity. If they are too far, the cooling will be slow; if they are too close, the local temperature of the cavity will be low, resulting in "cold scars" on the product.
Even distribution: For example, when making an automotive dashboard, more water channels should be opened in thick areas and fewer in thin areas. Otherwise, if the thick areas are not fully cooled before demolding, they will shrink inwards.
I once helped a client repair a set of molds. The products were always warping. After disassembling them, it was found that only half of the water channels were opened, while the other half was blocked. The uneven cooling caused this problem — sometimes, the problems are hidden in these invisible places.

4. Exhaust System: The "Breathing Holes" of the Mold
When plastic is injected into the mold cavity, it will compress air inside. If the air cannot be expelled, the product will have bubbles and burn marks (as the air is compressed to high temperatures, it will burn the plastic). The exhaust system is located at the final filled area of the mold cavity, with a small groove of 0.01-0.03mm deep, which can effectively expel the air without allowing the plastic to leak. 
For example, when making thin-walled parts (such as a 0.8mm mobile phone stand), the exhaust slots are particularly important. Even if they are slightly blocked, the product will run out of material; while for thick-walled parts, the exhaust slots can be a little wider to allow for a more thorough air discharge. 
5. Demolding System: The "Pusher" of the Product
After the plastic solidifies, the product needs to be pushed out of the mold cavity by the demolding system. The main components include pins and plates: 
Pin: The most commonly used type should be evenly distributed; otherwise, the product may be deformed by the force of the pin (for example, if a part only has a pin on one side, when pushed out, it will be skewed).
Inclined pin: When the product is upside down (such as a snap ring), and the pin cannot be pushed out, an inclined pin should be used. Push it in one direction and move it to the side simultaneously to "pull" the product out.
I have seen beginners install the pins incorrectly. If they didn't align the position properly, during the mold closing process, the pin would hit the core, and directly crack the core - although the demolding system is simple, installing it wrongly can result in heavy losses.