1. It is enough to have an exhaust groove or exhaust needle on mold;
2. Poor mold exhaust only causes trapped air (burning) or lack of glue;
3. The wider exhaust groove, the easier it is to produce flash (burrs) during injection molding;
4. Poor mold exhaust can be solved by adjusting injection molding machine ;
5. For same set of molds, gap size of exhaust system is same;
6. Mold exhaust grooves are only symmetrically distributed on mold parting surface;
7. Mold exhaust system is designed based on past experience;
8. Design of mold exhaust system is very simple;
9. The smaller gap of mold exhaust system, the better (to prevent flash);
10. Length of gap between mold exhaust groove or exhaust needle can be set at will;

1. Exhaust using exhaust groove;
2. Exhaust using gap between parting surface;
3. Exhaust using gap between core;
4. Exhaust using gap between ejector pin;
5. Exhaust using gap between lifter;
6. Exhaust using gap between sleeve;
7. Exhaust using gap between side core puller;
8. Exhaust using gap between insert;
9. Exhaust using gap between main gate bushing;

1. Exhaust groove must be located at the end of melt flow sealing position;
2. Number of exhaust grooves must be sufficient;
3. Width of exhaust groove should be as wide as possible;
4. Length of exhaust groove sealing position should be as short as possible (generally 0.8-1.2mm);
5. Exhaust grooves should also be opened at the end of main/dividing channel;
6. Structure of exhaust groove should be correct (sealing position in the front, and avoidance of air in the back);
7. Exhaust needle should be located at sealing position inside plastic part;
8. Number of exhaust needles should be sufficient;
9. Form of exhaust needle should be correct;
10. Rib/bone position of plastic part needs to be ejected with a flat ejector (using its gap for exhaust);
11. Screw column needs to be ejected with an exhaust-type ejector (using its gap for exhaust);
12. Inserts need to be added to "dead corner" of mold (using gap between inserts for exhaust);
13. Exhaust time should be less than injection time;
14. Mold exhaust requirements for thin-walled products (high-speed injection) are higher;
15. Plastics with poor thermal stability. Gap of exhaust groove should be increased;
Depth of common plastic exhaust groove (for reference)

 

Mold temperature regulation system is core of injection molding. Its role is to adjust viscosity of molten material entering mold cavity, reduce flow resistance, ensure that molten material smoothly fills every corner of mold cavity, cools and shrinks in a uniform state, and keeps molten material close to mold surface, improve appearance quality of plastic parts, improve stability of product size, reduce deformation of plastic parts, improve strength and toughness of product.

1. Prevent deformation of plastic parts;
2. Improve quality of plastic parts;
3. Adjust and control mold temperature;
4. Cool slider to avoid jamming;
5. Shorten molding cycle (increase production capacity);

 

1. After part is demolded, part will shrink and deform toward side with high mold temperature because shrinkage is larger on the side with high mold temperature;
2. The more water channels there are in mold, the more uniform mold temperature is, and the smaller deformation of part is.

Mold temperature will directly affect quality and injection efficiency of plastic parts. It must be optimized and structure of mold cooling system must be scientifically designed.
1. Number of mold water channels should be as large as possible (for uniform mold temperature);
2. Distance between mold water channels and surface of mold cavity should be as consistent as possible;
3. Water (oil) in mold should flow along shape of plastic part;
4. Arrangement of mold water channels should match shape of mold cavity as much as possible;
5. Diameter of mold water channel should be as large as possible (water channel aperture is generally 10-14mm);
6. Distance between water channel and cavity should not be less than 10mm (generally 15-20mm);
7. Distance between water channels (center distance) is generally 3-5 times diameter of water channel;
8. Cooling should be strengthened near runner and gate ( Water enters from vicinity of flow channel);
9. Temperature difference between inlet and outlet water temperatures should be as small as possible (within 3-5 degrees);
10. When wall thickness of plastic part is consistent, distance between water channel and mold cavity should be same;
11. When wall thickness of plastic part is different, cooling should be strengthened at wall thickness;
12. Cooling water channel should be avoided as much as possible at weld line of plastic part;
13. Cooling water channels should also be opened on the inside of slider;
14. Four corners of square plastic part should be cooled more;
15. Guide pin/guide sleeve of larger mold should also have cooling water channels;
16. Distance between cooling water channel and ejector pin hole and screw hole should not be too close (need to be greater than 5mm);
17. When water channel passes through insert, an "O" type sealing ring should be added (to prevent insert sleeve from leaking);
18. Increase number of cooling water channel inlets and outlets to shorten length of water flow, reduce temperature difference between inlet and outlet water;
19. For plastics with poor fluidity (high viscosity) or thin walls, a heating device should be installed;
20. Cooling of slender core should use a cooling surround core or use materials with high thermal conductivity (such as beryllium bronze) to make slender cores;
21. Add a thin copper rod to thicker part (diameter greater than 8mm) inside core, and then connect one end of thin copper rod in parallel to cooling water channel in mold plate;
22. Water inlet and outlet ports should be located in a position that does not affect mold opening operation, should be located on same side (behind injection molding machine) as much as possible;
23. Inlet and outlet ports of small mold water channel should not be too close to each other, so as to avoid difficulties in installing nozzles and fixing water pipes;
24. Inlet and outlet nozzles of cooling water channel should not be directly opposite position of injection molding machine Green column, so as to avoid difficulties in installing water pipes;
25. Water inlet should not be opened at position of plastic part weld line;
26. For multi-cavity precision plastic parts, each cavity should be temperature controlled separately by a mold temperature controller;
27. Heat insulation boards should be installed on the outside (four sides) and bottom of high-temperature mold (to prevent heat loss);
For later reading, please refer to "Talking about mold optimization from perspective of injection molding process 5. 6, 7, 8".