Mould Design Sharing- Gating System Design (Part 2)

Design of way of water inlet

Water inlet method is method by which material enters mold cavity, which is divided into two categories, that is, small water inlet method and large water inlet method.

1. Small water inlet way

Small water inlet method, also known as pin water inlet, is a water inlet method often used in plastic molds. Advantages of small water inlet method are many, and its layout design is free. It is not affected by layout, nor is it affected by lifter and rear mold slider. Disadvantages of small nozzle water inlet method are use of a small nozzle mold structure, relatively complicated mold structure, high mold cost, high mold processing cost, long processing time, and so on.
As shown in Figure 3.37, small water inlet system is shown. Its design includes:
① Water inlet point design;
② Design of spout orifice;
③ Design of pull pin;
④ Design of sprue bush;
⑤ Design of elastic rubber;
⑥ Design of nylon rubber shutter;
⑦ Design of limit pins;
⑧ Tie rod design.

1) Water inlet point design

Design of water inlet point is very important. If it is well designed, it will work normally during injection moulding with high efficiency, and nozzle will be broken flat without scratching. Appearance of "pointer needles" can stab people and hurt their hands. Design points are shown in Table 3.4.

Figure 338 analysis:
A: It is best to take 1.5-2, minimum should not be less than 1, and maximum should not be greater than 3.
B: It is best to take 20-30, minimum should not be less than 15, and maximum should not be greater than 45.
SR1: It is best to take R3-R5, minimum should not be less than R2mm, and maximum should not be greater than R7.5mm.
S2: It is best to take 2-3mm, minimum should not be less than 1.5mm, and maximum should not be greater than 5mm.
D: It is best to take 0.5-1.2mm, minimum should not be less than 0.3mm, and maximum should not be greater than 1.5mm.
M: It is best to take 3-4mm, minimum should not be less than 2.5mm, and maximum should not be greater than 5mm.
A: It is best to take 0.8-1.2mm. minimum should not be less than 0.5mm, and maximum should not be greater than 1.5mm.
B: It is best to take 0.4-0.6mm, minimum should not be less than 0.3mm, and maximum should not be more than 0.8mm.
C: It is best to take 0.4-0.6mm, minimum should not be less than 0.4mm, and maximum should not be more than 0.7mm.
Explanation:
1. Design a spherical recess on inner wall of product, as shown in SR1 position of Figure 338. This is very important, because when material is injected from water inlet, it first rushes to SR1 sphere, and SR1 sphere is evenly divided to improve material flow.
2. Design a recess M at water inlet. Its function is to prevent water from being punctured or injured if it is broken a little uneven, as long as it is not too high. This also needs to be noted. Generally, water inlet is designed with a recess, which is why this recess is usually designed in three shapes, as shown in Figure 339. All three shapes can be used, and most of them are currently applied in first shape.

2) Design of spout orifice

Runners of spout orifice are generally trapezoidal cross-section runners, which are processed on front mold plate. Path design of runner has different paths according to different products, as shown in Table 3.5, but it must adhere to following principles.
(1) Path should be designed with the shortest distance.
(2) Path should be designed to make flow smooth.
(3) Design of path should leave cold material slots.

In Figure 340:
Mainstream: This is determined by design of sprue gate. Specific design method will be explained in detail later.
Sub runner: first and second runner. This is determined by different products and layout.
Vertical runner: third branch runner in Figure 340. This runner must pass through front mold plate and front mold insert. For easy and smooth extraction of runner, runner on front mold plate is usually large, runner on insert is made smaller, and unilateral difference is B. Another important design is to align vertical runner, and to do pull pin, so that when mold is opened, vertical runner is pulled out by pull pin, and water inlet point of small nozzle is broken.
In Figure 340 and Figure 341:
T: Width of sub runner.
First runner: It is best to take T = 7-10mm, minimum should not be less than 7mm, and maximum need not be greater than 10mm.
Second runner: It is best to take T = 5-8mm, minimum should not be less than 5mm, and maximum should not be greater than 8mm.
Third runner: It is best to take T = 4-6mm, minimum should not be less than 4mm, and maximum need not be greater than 6mm.
Center mold (length and width: 300-500mm)
First runner: It is best to take T = 6-8mm, minimum should not be less than 6mm, and maximum should not be greater than 8mm.
Second runner: It is best to take T = 4-6mm, minimum should not be less than 4mm, and maximum should not be greater than 6mm.
Third runner: It is best to take T = 3-5mm, minimum should not be less than 3mm, and maximum should not be greater than 5mm.
For small molds (length and width below 300mm)
First runner: It is best to take T = 4-6mm, minimum should not be less than 4mm, and maximum need not be greater than 6mm.
Second runner: It is best to take T = 3-5mm, minimum should not be less than 3mm, and maximum should not be greater than 5mm.
H: thickness of T-shaped runner (unit: mm): H = 2/3 * T.
E: Hook head length of pull pin: It is best to take 2.5-3.5mm, minimum should not be less than 2mm, and maximum should not be greater than 4mm.
F: Thickness of ring rubber at the bottom of vertical runner. Its role is to increase width of inlet runner of vertical runner to eliminate influence of pull pin on vertical runner flow.
F is often taken as F = (1-1.2) * E (unit: mm).
L: Depth of vertical cold material tank. When mold takes a manipulator to take out runner during injection moulding production, this vertical cold material tank is a grip of robot, and L is usually taken 10-12mm.
R1: It is best to take 1.5-2.5mm.
D2: It is best to take 5-6mm.
A2: It is best to take 1.5-2.
A: It is best to take 0.8-1.2mm, minimum should not be less than 0.5mm, and maximum should not be greater than 1.5mm.
B: It is best to take 0.2-0.3mm, minimum should not be less than 0.15mm, and maximum should not be greater than 0.5mm.
A: It is best to take 1.5-2mm, minimum should not be less than 1.0mm, and maximum should not be greater than 2.5mm.
S2: It is best to take 2-3mm, minimum should not be less than 1.5mm, and maximum should not be greater than 5mm.
SR2: SR2 = S2 / 2.
A1: It is best to take 1.5-2, minimum should not be less than 1, and maximum should not be greater than 3.
A2: Take 3-5 often.
A3: It is best to take 3-5.
A4: Take 3-5 often.
R2: Preferably R1-R1.5mm.
G: It is best to take G = (1.5-2) * T.

3) Design of pull pin of small nozzle runner

In the design of small nozzle runner, when mold is opened, pull pin is responsible for pulling out vertical runner. It can be said that in the mold with a thin nozzle structure, if there is no pull pin, mold can hardly be produced. Therefore, design of pull pin is very important. Design of pull pin includes two aspects.
1. Design of position of pull pin. Generally, a pull pin is designed on each vertical runner, and a pull pin is responsible for pulling out a vertical runner. Figure 3.42 shows position of pull pin.

There are usually two types of position design of pull pin, one is center position design and the other is eccentric position design, see Table 3.6.

Figure 343 is center position design. This is a common design method. Its disadvantage is that W value is too small, which causes injection molding difficulties and high pressure. Generally, two solutions shown in Figure 345 and Figure 346 are used.
Figure 344 is eccentric position design. This is also a commonly used design method. Its advantage is to achieve purpose of increasing W value by eccentricity, eliminating influence of pull pin hook head on flow. Its disadvantage is that pulling force is smaller.
Eccentric value W: It is best to take 2-3mm, minimum should not be less than 1.5mm, and maximum should not be greater than 3.5mm.

Method in Figure 345 is to process a ring rubber with a thickness of F at the bottom end of vertical runner to increase W value and eliminate effect of pull pin on flow.
E: It is best to take 2.5-3.5mm, minimum should not be less than 2.0mm, and maximum should not be greater than 4mm.
F: It is best to take F = (1-1.2) * E.
E: It is best to take 1.5-2mm, minimum should not be less than 1.0mm, and maximum should not be greater than 2.5mm.
V: It is best to take 0.2-0.3mm, minimum should not be less than 0.15mm, and maximum should not be greater than 0.5mm.
Method in Figure 346 is to process an oblique rubber position on nozzle plate, and retract pull pin hook head to achieve purpose of increasing W value and eliminate influence of pull pin hook head on flow.
M: It is best to take 2-2.5mm.
M: It is best to take 0.2-0.3mm, minimum should not be less than 0.15mm, and maximum should not be greater than 0.5mm.
N: It is best to take 1.0-1.5mm, minimum should not be less than 0.8mm, and maximum should not be greater than 2mm.
A: It's better to take 45-60
2. Shape design of hook of pull pin. There are usually two types: one is a concave concave hook head, and the other is an arc concave hook head. These two structures are hook structure of pull pin commonly used at present, see Table 3.7.

Analysis:
A: It is best to take 2.5-3.5mm, minimum should not be less than 2mm, and maximum should not be greater than 4mm.
C: It is best to take 0.2-0.3mm, minimum should not be less than 0.15mm, and maximum should not be greater than 0.5mm.
D: It is best to take 0.2-0.3mm, minimum should not be less than 0.2mm, and maximum should not be more than 0.3mm.
R1: It is best to take R0.5mm, minimum should not be less than R0.3mm, and maximum should not be greater than R0.75mm.
R2: It is best to take R0.5-R0.75mm.

4) Design of sprue bush of small nozzle system

Design of sprue bush will directly affect injection moulding efficiency of small nozzle mold, especially in small nozzle mold with thick panel, which is more important. Usually divided into two types, standard gate sleeve and non-standard gate sleeve, structure of standard gate sleeve is shown in Table 3.8.

Analysis:
D: Metric standard is 16mm or 12mm.
H: It is best to take 6-10mm.
A: It's best to take 3-5.
From structure of Figure 349:
1. Gate sleeve must be installed on panel.
2. Fitting of gate sleeve and nozzle plate is oblique.
Generally, when panel is greater than or equal to 45mm, that is, when E≥45mm, a non-standard gate sleeve will be used. Structure of non-standard gate sleeve is shown in Table 3.9.

Function of Non-standard gate sleeve on Figure 350:
1, Used as a sprue sleeve;
2, with function of positioning ring;
3, with function of pull pin;
4, shortened length of main runner, which is conducive to injection and save material.
A: It is best to take 15mm, and minimum should not be less than 10mm.
B: It is best to take 15mm, and minimum should not be less than 12mm.
C: It is best to take 10-15mm.
D: It is best to take 50-55mm, maximum is generally not more than 60mm.
E: Thickness of panel.
F: Thickness of nozzle plate.
M: Matching hole with M6 screw.
D: Usually D = 3.2-3.5mm
D1: It is best to take 12-16mm.
D2: It is best to take 45-55mm, minimum should not be less than 40mm, and maximum should not be greater than 60mm.
D3: It is best to take D3 = 99.5mm. If positioning holes of injection moulding machine are different, change accordingly.
D4: It is best to take D4 = D3 + 30mm.
D5: It is best to take D5 = D3.
D6: It is best to take 70mm, minimum should not be less than 60mm, and maximum should not be greater than 80mm.
D7: It is best to take D7 = D1-1.5mm.
SR1: It is best to take SR1 = 20mm.
R2: It is best to take R10-R15mm.
A1: It is best to take 1.5-2.0, minimum should not be less than 1, and maximum should not be greater than 3.
A2: It is best to take 3-5.
A3: It's better to take 45.
A4: It is best to take 6-10, minimum should not be less than 5, and maximum should not be greater than 12.5.
A: It is best to take 2.5-3.5mm, minimum should not be less than 2mm, and maximum should not be greater than 4mm.

5) Design of elastic rubber of small nozzle system

Design of elastic rubber is to assist nylon rubber shutter and pull pin to open nozzle plate and front mold at the first time, that is, Ⅰ-Ⅰ parting (see Figure 3.37), especially mold with front mold slider. It is better to use elastic rubber to ensure parting order. When there are many vertical flow channels and water inlet points, use elastic rubber to ensure parting order. Design of elastic rubber is shown in Table 3.10.

Analysis:
D1: It is best to take 18-25mm.
D2: D2 = D1 + 6mm.
A: It is best to take 4mm, minimum should not be less than 3mm, and maximum should not be greater than 5mm.
B: It is best to take 25-30mm, minimum should not be less than 20mm, and maximum should not be greater than 35mm.
T: Amount of compression of elastic rubber, preferably 4mm, minimum should not be less than 3mm, and maximum should not be greater than 5mm.
M: Matching screws, commonly used M8.
G: G = T.

6) Design of Nylon rubber shutter for small nozzle system

7) Design of stopcocks for small nozzle system

8) Design of tie rod of small nozzle system

2. Water inlet method of large nozzle

Water inlet method of large nozzle is the most commonly used water inlet method in plastic molds, and it can be divided into 8 types according to structure classification:
① Common water inlet way;
② Way of water inlet at the bottom of large nozzle;
③ Submarine gate way;
④ Ox horn (also called banana) water inlet way;
⑤ Conversion of diving and horn water inlet way;
⑥ Water inlet mode from small water inlet to large water inlet;
⑦ Way of flash gate of large nozzle;
⑧ Rotary nozzle design with big nozzle inlet method.

1) Ordinary large water inlet way

Ordinary large water inlet way is the most commonly used method. Its advantages are: simple structure, convenient processing, fast injection speed, high production efficiency, easy pressure compensation, easy mold adjustment, easy mold modification, etc .; disadvantage is that there will be a small scar on the surface of product, which increases trimming workload of injection molder. There are usually three types of water inlet methods for ordinary large water inlets, see Table 3.11.

Analysis:
Three structures of Figure 352, Figure 353, and Figure 354 are all used in actual design, and there is not much difference in production, so no comparison is explained here. Relatively speaking, in practical applications, use of FIG. 352 and FIG. 353 is more. FIG. 355 is a cross-sectional view of FIGS. 352, 353, and 354.
A: It is best to take 1.0-1.5mm, minimum should not be less than 0.8mm, and maximum should not be greater than 2mm.
B1: It is best to take 2.0-4.0mm, minimum should not be less than 1.5mm, and maximum should not be greater than 6mm.
B2: It is best to take 2.0-4.0mm, minimum should not be less than 1.5mm, and maximum should not be greater than 6mm.
B3: It is best to take 3.0-5.0mm, minimum should not be less than 2.5mm, and maximum should not be greater than 8mm.
T: It is best to take 0.4-1.5mm, minimum should not be less than 0.25mm, and maximum should not be greater than 2mm.
A1: It is best to take 20-30, minimum should not be less than 10, and maximum should not be greater than 35.
A2: It is best to take 20-30, minimum should not be less than 15, and maximum should not be greater than 40.
A3: It is best to take 20-30, minimum should not be less than 15, and maximum should not be greater than 40.

2) Way of water inlet at the bottom of large nozzle

The biggest feature of water inlet at the bottom of large nozzle is that it directly feeding, and there is no nozzle mark on the surface. This is the biggest difference from ordinary large water inlet way. See Table 3.12 for way of water inlet at the bottom of large nozzle.

Analysis:
Pocket water inlet has a scar on large surface of product, which must be cut flat with water pliers. When large surface of the product has higher requirements, it cannot be used for water.
A1: It is best to take 1.0-1.5mm, minimum should not be less than 0.8mm, and maximum should not be greater than 2mm.
A1: It is best to take 0.4-1.0mm, minimum should not be less than 0.25mm, and maximum should not be greater than 1.2mm.
C: minimum cannot be less than 0.3mm.
B: It is best to take 1.5-2.5mm, minimum should not be less than 1.2mm, and maximum should not be greater than 4mm.
B: minimum cannot be less than 0.2mm.
A: It is best to take 5-10.

3) Sub gate way

Sub gate way is a common way to feed. Choice of inlet is flexible, and can be directly on outer surface or inner surface of potential product. Sub entry point can be made very small. If surface of product is textured, especially rough surface, entry point can hardly be seen on the surface of product, which is very hidden. In injection moulding production, sub gate will automatically cut off runner, which is fully automatic production conditions. This is extremely beneficial for large-scale automatic production. Sub gate is divided into two categories, that is, inlet from front mold and inlet from back mold.
1. Inlet from front mold: Water entry point is directly on front mold, and a small spot will be seen on the surface of product. There are many specific designs of inlet from front mold and water entry forms. Four water entry forms listed in Table 3.13 are commonly used forms, with Figure 3.57 and Figure 3.58 being the most commonly used.

Analysis:
A: It is best to take 2.0-3.0mm, minimum should not be less than 1.5mm, and maximum should not be greater than 3.5mm.
B: It is best to take 7-15mm, minimum should not be less than 5mm, and maximum should not be greater than 20mm.
C: It is best to take 10-15mm, minimum should not be less than 8mm, and maximum should not be greater than 18mm.
B: It is best to take 0.35-1.0mm, minimum should not be less than 0.25mm, and maximum should not be greater than 1.2mm.
d: It is best to take 1.8-2.2mm, minimum should not be less than 1.5mm, and maximum should not be greater than 2.5mm.
D: diameter of sub runner, usually D is 3-6mm.
a: It is best to take 35-45, minimum should not be less than 30, and maximum should not be greater than 50.
b: It is best to take 15-20, minimum should not be less than 10, and maximum should not be greater than 30.

Analysis:
A: It is best to take 2.0-3.0mm, minimum should not be less than 1.5mm, and maximum should not be greater than 3.5mm.
B: It is best to take 7-15mm, minimum should not be less than 5mm, and maximum should not be greater than 20mm.
C: It is best to take 10-15mm, minimum should not be less than 8mm, and maximum should not be greater than 18mm.
d: It is best to take 0.35-1.0mm, minimum should not be less than 0.25mm, and maximum should not be greater than 1.2mm.
D: Diameter of sub runner, usually D is 3-6mm
a: It is best to take 35-45, minimum should not be less than 30, and maximum should not be greater than 50.
b: It is best to take 15-20, minimum should not be less than 10, and maximum should not be greater than 30.

Analysis:
A: It is best to take 2.0-3.0mm, minimum should not be less than 1.5mm, and maximum should not be greater than 3.5mm.
B: It is best to take 7-15mm, minimum should not be less than 5mm, and maximum should not be greater than 20mm.
C: It is best to take 10-15mm, minimum should not be less than 8mm, and maximum should not be greater than 18mm.
B: It is best to take 0.35-1.0mm, minimum should not be less than 0.25mm, and maximum should not be greater than 1.2mm.
D: It is best to take 1.5-2mm, minimum should not be less than 1.2mm, and maximum should not be greater than 2.5mm.
D: Diameter of sub runner, usually D is 3-6mm
a: It is best to take 35-45, minimum should not be less than 30, and maximum should not be greater than 50.
b: It is best to take 15-20, minimum should not be less than 10, and maximum should not be greater than 30.

Analysis:
A: It is best to take 2.0-3.0mm, minimum should not be less than 1.5mm, and maximum should not be greater than 3.5mm.
B: It is best to take 0.35-1.0mm, minimum should not be less than 0.25mm, and maximum should not be greater than 1.2mm.
B: It is best to take 7-15mm, minimum should not be less than 5mm, and maximum should not be greater than 20mm.
C: It is best to take 10-15mm, minimum should not be less than 8mm, and maximum should not be greater than 18mm.
d: It is best to take 0.35-1.0mm, minimum should not be less than 0.25mm, and maximum should not be greater than 1.2mm.
D2: It is best to take 1.8-2.2mm, minimum should not be less than 1.5mm, and maximum should not be greater than 2.5mm.
D: Diameter of sub runner, usually D is 3-6mm
a: It is best to take 35-45, minimum should not be less than 30, and maximum should not be greater than 50.
b: It is best to take 15-20, minimum should not be less than 10, and maximum should not be greater than 30.
2. Inlet from back mold: The most commonly used methods in inlet water structure. According to form of water inlet, there are usually: inlet from gate of back mold, inlet from rubber position of back mold, inlet from thimble of back mold, inlet from shallow gate position. See Table 3.14.

Analysis: When rear mold has a glue position and is high enough to allow diving scars, a ejector pin can be discharged near water inlet and there must be sufficient ejection force to ensure smooth ejection when ejecting.In such conditions, sub gate of of FIG. 361 can be used.
Analysis:
A: It is best to take 2.0-3.0mm, minimum should not be less than 1.5mm, and maximum should not be greater than 3.5mm.
B: It is best to take 10-15mm, minimum should not be less than 7mm, and maximum should not be greater than 18mm.
C: It is best to take 10-15mm, minimum should not be less than 8mm, and maximum should not be greater than 18mm.
E: It is best to take 2.0-2.5mm, and minimum should not be less than 1.5mm.
B: It is best to take 0.35-1.0mm, minimum should not be less than 0.25mm, and maximum should not be greater than 1.2mm.
D: It is best to take 0.8-1.5mm, minimum should not be less than 0.6mm, and maximum should not be greater than 2.0mm.
D: Diemater of sub runner, usually D is 3-6mm
a: It is best to take 35-45, minimum should not be less than 30, and maximum should not be greater than 50.
b: It is best to take 15-20, minimum should not be less than 10, and maximum should not be greater than 30.

Analysis: When rear mold has a glue position and is high enough to allow diving scars, a ejector can be discharged near water inlet and there must be sufficient ejection force to ensure a smooth ejection when ejected. In such conditions, sub gate of of FIG. 362 can be used.
Analysis:
A: It is best to take 2.0-3.0mm, minimum should not be less than 1.5mm, and maximum should not be greater than 3.5mm.
B: It is best to take 10-15mm, minimum should not be less than 7mm, and maximum should not be greater than 18mm.
C: It is best to take 10-15mm, minimum should not be less than 8mm, and maximum should not be greater than 18mm.
E: It is best to take 2.0-2.5mm, and minimum should not be less than 1.5mm.
B: It is best to take 0.35-1.0mm, minimum should not be less than 0.25mm, and maximum should not be greater than 1.2mm.
D: It is best to take 0.8-1.5mm, minimum should not be less than 0.6mm, and maximum should not be greater than 2.0mm.
D: Diemater of sub runner, usually D is 3-6mm
a: It is best to take 35-45, minimum should not be less than 30, and maximum should not be greater than 50.
b: It is best to take 15-20, minimum should not be less than 10, and maximum should not be greater than 30.

When ejector pin is allowed to be enlarged with rear mold of product, there is enough space. Diving method shown in Figure 363 can be used. However, this method of water inlet may cause a hazy dark spot on outer surface of product directly opposite plastic inlet. If outer surface of product is not very demanding, it can be used. If appearance requirements of product are very high, it is better not to use it when dark spots are not allowed, and think of other methods. If you must use it, you must explain it to customer to avoid unnecessary disputes in the future.
A: It is best to take 2.0-3.0mm, minimum should not be less than 1.5mm, and maximum should not be greater than 3.5mm.
B: It is best to take 10-15mm, minimum should not be less than 7mm, and maximum should not be greater than 18mm.
C: It is best to take 10-15mm, minimum should not be less than 8mm, and maximum should not be greater than 18mm.
E: It is best to take 2.0-2.5mm, and minimum should not be less than 1.5mm.
A: It is best to take 1.8-2.2mm, minimum should not be less than 1.5mm, and maximum should not be greater than 2.5mm.
B: It is best to take 0.35-1.0mm, minimum should not be less than 0.25mm, and maximum should not be greater than 1.2mm.
C: It is best to take 0.2-0.4mm, minimum should not be less than 0.1mm, and maximum should not be greater than 0.5mm.
R: It is best to take R1.5-R3mm.
d: It is best to take 0.8-1.5mm, minimum should not be less than 0.6mm, and maximum should not be greater than 2.0mm.
D: Diemater of sub runner, usually D is 3-6mm.
D1: It is best to take 4.0-6.0mm.
a: It is best to take 35-45, minimum should not be less than 30, and maximum should not be greater than 50.
b: It is best to take 15-20, minimum should not be less than 10, and maximum should not be greater than 30.
Y: It is best to take 5-15.

Analysis: When product back mold does not allow large ejector pins, but small ejector pins can be used, diving method shown in Figure 364 can be used. This small ejector pins be a Stepped E.P. This way of water inlet may have a hazy dark spot on outer surface of product directly opposite plastic inlet (ie, point M).If outer surface of product is not very demanding, it can be used. If appearance requirements of product are very high, it is better not to use it when dark spots are not allowed, and think of other methods. If you must use it, you must explain it to customer to avoid unnecessary disputes in the future.
A: It is best to take 2.0-3.0mm, minimum should not be less than 1.5mm, and maximum should not be greater than 3.5mm.
B: It is best to take 10-15mm, minimum should not be less than 7mm, and maximum should not be greater than 18mm.
C: It is best to take 10-15mm, minimum should not be less than 8mm, and maximum should not be greater than 18mm.
E: It is best to take 2.0-2.5mm, and minimum should not be less than 1.5mm.
B: It is best to take 0.35-1.0mm, minimum should not be less than 0.25mm, and maximum should not be greater than 1.2mm.
d: It is best to take 0.8-1.5mm, minimum should not be less than 0.6mm, and maximum should not be greater than 2.0mm.
D: Diemater of sub runner, usually D is 3-6mm.
D1: Diemater of small ejector pin is preferably 2.0mm, minimum should not be less than 1.5mm, and maximum should not be greater than 2.5mm.
D2: Gating diameter of plastic inlet, D2 = D1 + 0.2mm.
a: It is best to take 35-45, minimum should not be less than 30, and maximum should not be greater than 50.
b: It is best to take 15-20, minimum should not be less than 10, and maximum should not be greater than 30.

Analysis:
When product allows a thin process film to be used as inlet from thick wall, and then cut out film after injection moulding, advantages of this water penetration are that there are no water scars and dark spots on outer surface of product.
A: It is best to take 2.0-3.0mm, minimum should not be less than 1.5mm, and maximum should not be greater than 3.5mm.
B: It is best to take 7-12mm, minimum should not be less than 5mm, and maximum should not be greater than 15mm.
C: It is best to take 10-15mm, minimum should not be less than 8mm, and maximum should not be greater than 18mm.
E: It is best to take 2.0-2.5mm, and minimum should not be less than 1.5mm.
A: It is best to take 2.0-2.5mm, and minimum should not be less than 1.5mm.
B: It is best to take 0.35-1.0mm, minimum should not be less than 0.25mm, and maximum should not be greater than 1.2mm.
C: It is best to take 0.9-1.2mm, and minimum should not be less than 0.7mm.
d: It is best to take 0.8-1.5mm, minimum should not be less than 0.6mm, and maximum should not be greater than 2.0mm.
D: Diemater of sub runner, usually D is 3-6mm.
a: It is best to take 35-45, minimum should not be less than 30, and maximum should not be greater than 50.
b: It is best to take 15-20, minimum should not be less than 10, and maximum should not be greater than 30.

Analysis:
This is sub water inlet way for thin product. Its characteristics are that product is not thick. However, to directly dive into water, runner must have good elastic deformation to get out of diving port smoothly.
A: It is best to take 1.5-2.0mm, minimum should not be less than 1.2mm, and maximum should not be greater than 2.5mm.
B: It is best to take 4-5mm, and minimum should not be less than 3mm.
C: It is best to take 10-15mm, minimum should not be less than 8mm, and maximum should not be greater than 18mm.
E: It is best to take 1.5-2mm, and minimum should not be less than 0.8mm.
B: It is best to take 0.35-0.8mm, minimum should not be less than 0.25mm, and maximum should not be greater than 1.0mm.
d: It is best to take 0.8-1.5mm, minimum should not be less than 0.6mm, and maximum should not be greater than 2.0mm.
D: Diemater of sub runner, usually D is 3-6mm.
a: It is best to take 45-50, minimum should not be less than 40, and maximum should not be greater than 65.
b: It is best to take 20-30, minimum should not be less than 15, and maximum should not be greater than 35.

4) Ox horn (also called banana) water inlet way

Small water inlet will have a inlet scar on outer surface of product. Ordinary large water inlets, water inlet at the bottom of large nozzle, inlet from front mold will also have scars on outer surface of product. Inlet from back mold will have large scars inside product. All these are not allowed for high-demand products. Ox horn (also called banana) water inlet way can inlet water inside product, and scar is just a small point. If you don't look carefully, you can't see it at all which meets high requirements of high-end products, such as mobile phone casings and handheld computer casings.
As shown in Table 3.15, horn inflow method must be designed with two pieces of horn inserts Ⅰ and Ⅱ. Half of horn-curved arc runners are processed on horn insert Ⅰ, and the other half of horn-curved runners are processed on horn insert Ⅱ. Inserts Ⅰ and Ⅱ together form a complete horn-shaped water inlet runner and water inlet. During ejection, horn-shaped curved runner and break-in point are pulled out through deformation of horn-shaped runner and sub runner. Therefore, horn-shaped runner needs to be processed into a curved arc-shaped runner, so that it is easy to pull out without breaking. There must be a free length on sub runner, that is, distance from root of horn runner to eject pin. This length is also to leave space for deformation of runner. This is very important, otherwise there is a danger that horns runner will not be pulled out.

Analysis:
E: It is best to take 25-30mm, minimum should not be less than 22mm, and maximum should not be greater than 35mm.
F: It is best to take 8-10mm, minimum should not be less than 6mm, and maximum should not be greater than 12mm.
A: It is best to take 5-6mm, minimum should not be less than 4mm, and maximum should not be greater than 8mm.
B: It is best to take 10-12mm, minimum should not be less than 10mm, and maximum should not be greater than 15mm.
C: It is best to take 12-15mm, minimum should not be less than 10mm, and maximum should not be greater than 18mm.
A: It is best to take 1.5-2.0mm, minimum should not be less than 1.5mm, and maximum should not be greater than 2.5mm.
R: It is best to take R12-R15mm, minimum should not be less than R10mm, and maximum should not be greater than R20mm.
SR: It is best to take SR1.0-SR1.5mm, minimum should not be less than SR0.75mm, and maximum should not be greater than SR1.75mm.
D: Diemater of sub runner, usually D is 3-6mm.
D1: Diemater of horn runner is best to be 5.5-6.5mm, minimum should not be less than 4.5mm, and maximum should not be greater than 7.5mm.
D2: It is best to take 2.0-3.0mm, minimum should not be less than 1.5mm, and maximum should not be greater than 3.5mm.
d: It is best to take 0.35-1.0mm, minimum should not be less than 0.25mm, and maximum should not be greater than 1.2mm.
a: It is best to take 35-45.
Material of horn inserts is generally 738 or 718H and heat treated to HRC53 ° ~ 55 °. Sometimes it is also processed directly with NAK80 material. NAK80 is an imported pre-treatment mold steel with a hardness of HRC38 ° ~ 42 °. Because horn runner is a curved arc-shaped runner, there is no section of same size from beginning to end. Diameter of horn runner usually refers to diameter of section at the apex of horn runner. See cross section diameter φD1 at A’-A‘ in Figure 3.67, resistance of horn runner when ejecting is quite large, so horn runner is usually polished to be smooth, almost to degree of mirror surface.

5) Conversion of diving and horn water inlet way

When product is high or product is more complicated, horns need to be designed to water inlet, but camber is too large. it is easy to break horn runner when ejecting. In this case, diving + horns are usually used. Way of water inlet is shown in Table 3.16. Horn runner is processed on straight top. When ejecting, horn runner on straight top is disconnected from sub runner. Horn runner will be ejected along with straight top and product. Then, when removing product, take horn runner from straight top. Therefore, horn-shaped runners on straight roof are often made into "ladder" runners, and slope is as large as possible to facilitate removal.

It can be seen from Figure 368 that inlet of horn-shaped runner on straight top can be arbitrarily changed as long as it is within width of straight top, so flexibility of inlet selection is very high. Disadvantage is that runner on straight top must be removed manually during injection molding.
T: It is best to take 4-5mm, minimum should not be less than 3mm, and maximum should not be greater than 6mm.
H: H = 2/3 * T.
A: It is best to take 10-15, minimum should not be less than 10, and maximum should not be greater than 15.

6) Water inlet from small nozzle to large nozzle

In some production processes, product needs to be fed through large nozzle. Small nozzle is not allowed. There is no perforation on the top of product, product only comes out of one cavity, layout in the middle. In other words, either mold should be eccentric, or nozzle design should be changed. If eccentric, if product is smaller, it can still be used. Once product is large, if it is also designed to be eccentric, which will lead to excessive eccentric torque and affect stability of entire mold, even make it impossible to produce. Generally, eccentricity between center of mold and center of gate sleeve rarely exceeds 30mm, so it is necessary to design conversion of nozzle runner. Design of runner from small nozzle to large nozzle is shown in Table 3.17.

Figure 369 and Figure 370 are design of water inlet method from small nozzle to large nozzle. Product center can be designed in the center of mold, center of gate sleeve and top hole can also be designed in the center of mold, which is ideal mold design. Because working state of mold is the best and most stable. Water inlet of product is at point A on the side of product, from center point of mold to water inlet of point A, and process of turning small nozzle runner into large nozzle runner is to complete conversion of water inlet mode. In Figure 369, transition point between small nozzle runner and large nozzle runner is at point B, which is front side of front mold plate, so that total length of small nozzle runner is L1. In Figure 370, transition point between small nozzle runner and large nozzle runner is at point B, which is back side of front mold plate. In this way, total length of small nozzle runner is L2. Obviously, L2 is much shorter than L1. However, the shorter length of small nozzle runner, the shorter tie rod, the shorter distance of front mold plate from panel, the shorter force of long nozzle column of small nozzle, the more favorable is stable work of mold. Design of Figure 370 is better than that of Figure 369. In the absence of special circumstances, design structure of Figure 370 is used as much as possible.

7) Way of film gate of large nozzle

When product's water-entry position is very thin, or it is a flat product, in order to make hot melt evenly enter mold cavity at the same time, make hot melt flow in parallel to reduce deformation of product. For products such as mobile phone side keys where material level is very thin and middle is thick, film gate of large nozzle can greatly reduce flow distance and increase injection flow rate, make up pressure, etc., to eliminate special problems of special product structures. See Table 3.18 for way of film gate of large nozzle.

Analysis:
A: It is best to take A = 2/3 * T, but maximum A should not be greater than 1.2mm.
B: It is best to take 2-2.5mm, and minimum should not be less than 1.5mm.
E: It is best to take 1.5-2mm, minimum should not be less than 1.0mm, and maximum should not be greater than 2.5mm.
T: Thickness of product.
A: Usually 45, minimum should not be less than 30, and maximum should not be greater than 60.

Analysis:
It is usually used below T <0.6mm, especially when T is less than 0.4mm. When T> 0.7mm, use the normal large water inlet method.
A: It is best to take A = T-0.1mm, minimum should not be less than A = T-0.15mm, and maximum should not be greater than A = T-0.05mm.
B: It is best to take 1.5-2.0mm, minimum should not be less than 1.0mm, and maximum should not be greater than 2.0mm.
E: It is best to take 1.5-2mm, minimum should not be less than 1.0mm, and maximum should not be greater than 2mm.
T: Thickness of product.
A: Usually 45, minimum should not be less than 30, and maximum should not be greater than 60.
Figure 3.71 is water inlet method for flat products, and Figure 3.72 is water inlet method for small solid keys. These are typical examples of sheet water inlet method. Removal of spout by film gate of large nozzle is usually carried out by a punch, and cost is relatively high.

8) Rotary nozzle design with big nozzle inlet method

When there are multiple products, ejection method, ejection method, and water inlet method are basically same. They are all large water inlets, and they may be composed of two colors or two materials. These products are usually small, and quantity produced is not large. In this case, customers often put forward that these products are required to be manufactured on a set of molds, they can also be injected by material and color. This can save one or two sets of mold manufacturing costs, usually in the case of new product development, small batch trial production of new products will require this mold structure. See Table 3.19 for rotary nozzle design with big nozzle inlet method.

Analysis:
A: It is best to take 35-40mm, minimum should not be less than 30mm, and maximum should not be greater than 45mm.
B: It is best to take 35-40mm, minimum should not be less than 30mm, and maximum should not be greater than 45mm.
C: It is best to take 8-12mm, minimum should not be less than 6mm, and maximum should not be greater than 15mm.
D: It is best to take 20-22mm, minimum should not be less than 18mm, and maximum should not be greater than 25mm.
E: It is best to take A-12mm, minimum should not be smaller than A-10mm, and the largest should not be larger than A-15mm.
F: It is best to take B-12mm, minimum should not be less than B-10mm, and maximum should not be greater than B-15mm.
T: Size of sub runner, usually T takes 3.5-6.0mm.
H: H = 2/3 * t.
a: It is best to take 10, minimum should not be less than 5, and maximum should not be greater than 15.
Product 1 and product 2 have same materials, colors, and production quantities, so these two products can be arranged and designed on one side. Materials, colors, and production quantities of products 3 and D are same, so these two products can be arranged and designed on one side and share a sub runner. Sub runner diverter is fixed on rear mold insert (that is, the B insert). Sub runner diverter can be assembled by reversing direction. Center of sub runner diverter must be aligned with center of ejector pin. Otherwise, After sub runner diverter changes direction, nozzle of diverter won't fit. Fastening screw position of diverter steering element must be completely symmetrical, axis of symmetry is X and Y axis of sub runner steering element. Otherwise, after direction of sub runner diverter is reversed, fastening screw position will not be matched. Pay attention to it when designing.
Diverter on sub runner in Figure 373 is connected to 3 and 4 products. That is to say, at this time, injection molded products are 1 and 2, 3 and 4 products cannot be injection molded. Because sub runner diverter does not connect sub runners of 3 and 4 products.
Similarly, diverter on sub runner in Figure 374 is connected to 3 and 4 products, and products injected from mold are 3 and 4 instead of 1 and 2 products.
In production, we can first install sub runner diverter according to Figure 373, that is, injection molding 1 and 2 products. When injection quantity is enough, then stop, remove sub runer diverter and then install according to Fig. 374 . At this time, materials in barrel of injection molding machine are replaced, 3 and 4 products can be injection molded. At this point, production of products with different molds and different materials is completed.
In mold with switchable nozzle structure, trapezoidal runners are generally used because trapezoidal runners are processed on only one plate, so that only one diverter runner can be made. Simple structure, convenient processing and fast speed. If sub runner is a circular runner, diverter runner must be designed in two pieces, both front and back mold must be done, which is very troublesome. When designing sub runner diverter, follow runner of mold, that is, when trapezoidal runner of mold is opened in front mold, sub runner diverter is fixed in front mold. When trapezoidal runner of mold is opened in rear mold, sub runner diverter is fixed in rear mold.

Gud Mould Industry Co., Ltd