Mold bases are produced by professional manufacturers, have been standardized and serialized. When ordering mold bases, you only need to select appropriate model according to mold base data provided by mold base factory. However, sometimes you also need to customize mold bases (such as hot water nozzle molds). At this time, you can refer to standard mold base data and design your own mold base. To determine which model of mold base to use, you must first arrange mold, determine size of inner mold material, then determine size and model of mold base.
Table 1-1 Distance from product to steel edge

1: Determine inner mold material (mold Insert)
2: Distribution of screws on inner mold material
3: Select mold base (MoldBase)

1. Determine inner mold material, which is to arrange mold. According to shape and size of product, determine arrangement method of product in mold, so as to determine size and thickness of inner mold material. Following introduces some basic requirements for mold arrangement.
1) When a piece of inner mold material has multiple cavities, size of inner mold material generally does not exceed 200×200mm. Distance between products is generally 12~20mm (under special circumstances, it can be less than 3mm). For deep cavity parts such as cups and boxes, distance between two products is about 1/3~1/2 of product depth. When water entry is sub-gate, there should be enough space for sub-gate, and distance between two products should not be less than 20mm.
2) Distance from product to edge of steel material is 15~50mm. Distance from product to edge of steel material is related to thickness of product. For general products, empirical values in Table 1-1 can be referred to for selection, and large products need to be determined by calculation.
3) Depth of core (inner mold material) is more than 28mm, thickness of inner mold material of front and rear molds is related to plane projection area of product. For general products, empirical values in Table 1-2 can be referred to for selection. Large products need to be determined by calculation.
6) For all molds with pillows, pillows must avoid water entry (Runner). If it cannot be avoided, a water outlet iron (Runner Bar) must be added, or pillows should not be made through to leave a flat position for water to flow. As shown in Figure 1-3.

 

Figure 1-3 Pillow position should avoid water outlet

7) When product has a large parting or pillow position, Shut Off can be omitted unless customer requires it. For flat molds without parting or pillow position, Shut Off must be made. As shown in Figure 1-4.

 

Figure 1-4 Positioning corner

8) When size of inner mold material is less than 100mm×100mm, Shut Off size is 15mm×15mm, height 8mm, 7-degree beer handle. When size of inner mold material is greater than 100mm×100mm, Shut Off size is 22mm×22mm, height 8mm, 7-degree beer handle. See Table 1-3.

Table 1-3. Shut Off size

9) Shut Off interlocks inner mold materials of front and rear molds so that their doors cannot be misaligned with each other to ensure that product has no clamping. Shut Off is generally made at four corners of inner mold material. When it is necessary to avoid water outlet, it can be made at other positions. Shut Off edge should be at least 5mm away from glue position edge.
10) All beryllium copper molds must be equipped with a runner bar. For purpose of making samples, if patterns of hand-made castings are complex, it is impossible to ensure that multiple castings can be completely consistent. Same product cannot be produced in multiple pieces on one beryllium copper. Of course, if patterns are simple and multiple castings can be consistent, or if there are slight differences and customer can accept them, two or more castings can be made, and same product can also be produced in two or more pieces on one beryllium copper. Since beryllium copper molds are expensive, distance from edge of glue position to edge of steel material is generally 8mm~10mm.
11) Slider of beryllium copper mold is generally inlaid, but if bottom of slider foot is carved, slider is also original (this slider is not made of beryllium).
12) Method of mold arrangement for engraving molds depends on whether product has parting:
12-1) When there is no parting (plane parting line surface), there is nothing special about arrangement.
12-2) When there is a parting line (non-planar parting line surface), there are two cases.
① For solid figures or hands and feet, it is determined whether they need to be cut separately according to parting line height, and a runner bar needs to be added.
Mold Base Selection
When selecting a mold base, you should choose a side gate system mold base according to water entry method, as shown in Figure 1-1. Or a pin point gate system mold base, as shown in Figure 1-2. Or a simplified pin point gate system mold base, as shown in Figure 1-3. Choose whether to use a mold base with a stripper plate according to ejection method, choose whether to use a mold base with a support plate according to insert situation, decide whether to add a spacer block according to product height, etc.

 

Figure 1-1 Large nozzle system mold base

 

Figure 1-2: Pinhole system mold base

 

Figure 1-3 Simplified pinhole mold base
If mold base width is less than 250mm (including 250mm), use an I-shaped mold base (it is not convenient to make a clamping slot if mold base width is less than 250mm). If mold base width is greater than 250mm and less than 400mm, use a straight mold base with a top clamp plate. If mold base width is greater than 400mm (including 400mm), use a straight mold base without a top clamp plate (when there is a slider, use a straight mold base with a top clamp plate as appropriate). Straight mold base must be processed with a w25mm×h20mm clamping slot. Clamping slot is shown in Figure 1-4. Table 1-1 is data for processing clamping slot. Bottom panel must have a mounting screw hole (center distance: 7", 10", 14", center distance 7" with Ø1/2-13×1" thread, center distance: 10", 14" with Ø5/8-11×1" thread, depth 19~24mm). Mold base is generally made of yellow-brand medium carbon steel with a hardness of no less than HB170.