1. Interference Analysis (pay special attention to potential deformation of certain parts).
2. Check draft angle based on part's biting pattern to see if it is adequate. (Note that mating areas and important exterior surfaces must be indicated on drawing; do not leave this to mold designer.)
● Regulations of machining industry: If demoulding angle is not specified, when opening mold: outer shape - large end is as large as drawing, hole - small end is as large as drawing

 

3. Check whether fitting clearance is appropriate.
(1) Fitting clearance between fixing parts of small parts is 0.05~0.1mm (large parts need to be larger), as shown in Figure 4.3.1;
(2) Clearance between surface and bottom shell of small parts is 0.05~0.1mm (large parts need to be larger), as shown in Figure 4.3.2;
(3) Movable clearance (single side) of regular button (diameter 0015) is 0.1~0.2mm; movable clearance (single side) of regular button (diameter 0>15) is 0.15~0.25mm; movable clearance of special-shaped button is 0.3~0.35mm, as shown in Figure 4 3.3.

 

4. Sudden changes in adhesive thickness:

 

5. Sharp corners can easily cause product deformation:

 

6. Improper rib thickness
Rib: Rib thickness should be less than or equal to 0.5mm (t is wall thickness of part). Generally, rib thickness ranges from 0.8mm to 1.2mm.
When rib depth exceeds 15mm, adhesive flow may become difficult and air may be trapped. Inserts can be placed in mold to reduce mold size and facilitate air venting.
For rib depths less than 15mm, draft angle should be at least 0.5mm. For rib depths greater than 15mm, thickness difference between base and top should be no less than 0.2mm.

 

1. For molds with short service lives, P20 is generally used.
2. For molds with long service lives for non-transparent parts, use 718H or 738H.
3. For transparent parts, use NAK80 or S136(H).
4. For lifter materials, use SKD61 (quenched).
5. For molds with high surface quality requirements (such as mobile phones, MP3 players, and cameras) or for high production volumes, heat treatment or surface nitriding is generally recommended.
6. Except for stainless steel (such as M310, S136, M300, 136H, 2316VOD, 2316ESR, and PAK90), all other steels can be nitrided. After nitriding, surface hardness reaches HRC59 or above, and thickness and depth are 0.00mm. 5 to 0.2mm.

(Alignment refers to arrangement of one or more required plastic parts according to customer requirements, appropriate injection molding process and mold structure.)
1. Electroplated and spray-coated parts should not be placed in same mold as non-electroplated and non-spray-coated parts to prevent production mismatches due to scrap during electroplating or spray-coating process.
2. Products that may be used as shared parts in the future should not be produced in same mold as other products.
3. Strive for cavity pressure balance. Cavity pressure is divided into two components: axial pressure parallel to mold opening direction; lateral pressure perpendicular to mold opening direction. Alignment should ensure that axial and lateral pressures are balanced relative to mold center to prevent overflow and batch peaks.
Methods for achieving pressure balance:
A. Uniform and symmetrical alignment. Axial balance is shown in Figure 3.1.1; lateral balance is shown in Figure 3.1.2.
B. Using mold structure for balance is shown in Figure 5.1.4. This is a commonly used method for balancing lateral pressure.

 

1. Treatment of Parting Surface for Small Holes.
A. Direct penetration, as shown in Figure 5.2.9, is suitable for structures with relatively flat penetration areas. However, for "keyboard"-style keyholes (Figure 5.2.10a), to change direction of potential "bursts," a through-hole design with appropriate dimensions is often used, as shown in Figure 5.2.10b.

 

 

B. Middle plane is penetrated as shown in Figure 5.2.11a. It is suitable for structures with steep penetration points (such as air vents on curved surfaces).

 

There are usually four methods for making text and patterns on molds:
(1) Sun-drying text and patterns (also known as chemical corrosion);
(2) Electrode discharge (engraving electrodes or CNC processing electrodes); (If it is a concave character, it must be proposed before the mold is opened)
(3) Engraving or CNC direct processing of mold (when requirements are not high and simple)
(4) Electroforming (usually used in key mold opening. It is used when symbol is required to have a high gloss effect after electroplating, but cost is high, electroforming cavity has a short life and a long production cycle (about 18 days). At the same time, strength and hardness are poor, it is easy to damage. Therefore, it is important to remember to make accessories when opening mold. Electroforming cavity must be increased when it is customized to prevent product from being scrapped due to height change.