① Slide material: Generally, it should be different from inner mold material with which friction occurs. If this is unavoidable, slide should be nitrided.
② Slide positioning direction: Taking into account factors such as gravity, water transport, and part removal, positioning direction priority is as shown in Figure 5-1: right (anti-operation side), left (operation side), bottom (ground), and top (top), based on movable mold reference angle. Hydraulic core pulling is generally performed on the top side.

 

Figure 5-1 Priority of slide direction
③ A slide that can be used as a rear mold slide cannot be used as a front mold slide.
④ When slide has mold opening sequence requirements, a stroke greater than 60mm, or a slide weight exceeding 200kg, hydraulic core pulling should be used for safety reasons. However, hydraulic core pulling can pollute environment, increase production cycle time, and is not suitable for mold heating. It also makes it difficult to construct a slide ejector mechanism.
⑤ To prevent ejector pins from damaging slide due to improper resetting, avoid placing ejector pins underneath slide.
⑥ If there are many glue spots on slide, add cooling water, consider whether water inlet and outlet pipes interfere with shovel base, as shown in Figure 5-2.

 

Figure 5-2 Avoidance of gaps between shovel base and water inlet and outlet pipes
⑦ Slide Operation Principle and Design Key Points: Operation Principle: Utilizing mold opening action of molding machine, inclined guide column and slide generate relative motion, causing slide to move in mold opening direction and horizontally, freeing slide from part inversion, as shown in Figure 5-3. Design key points are as follows:

 

Figure 5-3 Key points of slide design

 

Figure 5-4

 

① When slide width (W) is greater than 50mm, a back pressure plate and wear plate must be installed. Plate thickness (T) is available in 6, 8, 10mm specifications and secured with flat-head screws, as shown in Figure 5-5.

 

Figure 5-5 Use of slide back pressure plate and wear plate
② For ease of adjustment, if slide weight exceeds 200kg, consider adding adjustment plates on both sides, as shown in the figure, and secure with flat-head screws, as shown in Figure 5-6.

 

Figure 5-6 Using slide side adjustment plate

 

① To ensure smooth and reliable slide movement, slide tube position is: L1 = 0.6 x L or L1 = 0.6 x H (whichever is greater).
② To prevent slide from slipping out of mold: Length of slide to inner mold is: K = S + 3-5 mm (this requirement is not required if point A is an inclined surface). Clearance at the end of slide is: T > S.
③ To facilitate slide assembly and disassembly, slide slot in plate B must be open, unless mold frame strength or positioning requirements are considered, as shown in Figure 5-7.

 

Figure 5-7 Sliding slot opening

 

When designing length of inclined guide pins, please note: Slide stroke S1 = S + (0.2-0.5) mm

As shown in Figure 5-8.

 

Figure 5-8 Inclined Guide Pin Locking Methods

To prevent slide from retreating under pressure during injection, which could affect size and appearance of finished product (such as flash), slide must have a locking mechanism, commonly called a shovel base. Common locking methods are as follows:
① Original mold base is retained: Suitable for slides with B > 30, as shown in Figure 5-9:

 

Figure 5-9 Original body leaves shovel base
When slide depth in front mold exceeds 2/3B of glue level, it is best to use original mold base as shovel base. If glue level on the slide is large, a reverse shovel should be used: shovel base height A must be greater than 2/3B (glue level height). Note: Guide post is trailed to ensure smooth slide operation and increase strength of shovel base. When slide is on upper side, consider whether guide post protrudes too far from PL surface to prevent robot removal. Inclined guide pins are guided by guide pins as they enter runner holes. Mold guide pins must be of sufficient length to provide this guidance and prevent damage.
② Inlaid shovel base, as shown in Figure 5-10:

 

Figure 5-10 Inlaid shovel base
When runner depth is primarily in rear mold, shovel base is constructed as an insert. If glue area on runner is large, a backshovel is required (as shown in shaded area in figure). If glue area on runner is small, this is not necessary. However, shovel base height A must be greater than 2/3 B (glue height). Note:
1. If needed, a back pressure plate can be installed on shovel. Even for very small runners, shovel or runner can be hardened directly.
2. To prevent inclined guide pins from being stressed during mold closing, consider applying stress to shovel base before inclined guide pins, as in the example of D > C.
3. Numerical ratio of shovel base positioning portion to pressure-bearing surface is:
L1 ≥ 1.5 L2
L3 ≥ L1

Bending pin and slide are driven by mold opening action of molding machine to create relative motion. Bending pin's surface B moves slide, causing it to move both in mold opening direction and horizontally, disengaging undercut. As shown in Figure 5-11;

 

Figure 5-11 Design of bent pin
B surface angle = A ≤ 20° (angle of bent pin);
H1 = 2/3H (H1 is mating length);
S ≈ S1 ≥ T + 4 mm (S1 is slide travel; T is undercut of finished product);
C is pressing surface, so bent pin core pulling type generally does not require a shovel base (no gaps);
1. Used in applications with a small forming area and limited slide space, or in the front mold slide;
2. To prevent slide backlash and breakage, a backshovel should be added if slide's adhesive surface has a large pressure-bearing area;
3. Order of assembly and disassembly should be considered during design;

Slide moves a certain distance during mold opening. Therefore, to ensure safe return to its original position, a positioning device must be installed. Positioning device must be flexible and reliable to ensure slide remains in place. Common positioning devices are as follows:
① Internal spring with screw, as shown in Figure 5-12a); commonly used for left and right side and ground side slides with a travel S1 less than 15mm. This structure is simple and convenient.

 

Figure a)
② External spring with stopper, as shown in Figure 5-12b); commonly used for slides with a travel S1 greater than 15mm or for top side slides. Note: Consider whether external spring will interfere with injection molding machine's collar or eye.

 

Figure b)
③ Internal spring with stopper, as shown in Figure 5-12c); commonly used for slides with a travel S1 less than 15mm, but where B-plate slide's movement space is insufficient for a screw.

 

Figure c)

① Universal Slide Spring:

 

S1: Slider travel; L: Slingshot free length; L1: Slingshot hole depth; n: Slingshot preload; F: Slingshot preload; G: Slider weight; L=1.5 times L1; F=n*slingshot stiffness; Top side slide: G≤2.5 times F; Side slide: G≤1.5 times F; Ground side slide: G<1 times F
② When L/D > 4, an auxiliary pin guide must be added to spring's inner hole to prevent spring bending, as shown in Figure 5-13.

 

Figure 5-13 Design of slide spring auxiliary needle

Common slide insert connection methods are shown in Figure 5-14. For slides with simple gluing geometry and short slide travel, a monoblock design may be considered. Note: Under no circumstances should headless screws be used to secure slide insert.

 

Figure 5-14 Connection method of slide inserts

Sliders must move smoothly and steadily to prevent binding or jumping in mold. Otherwise, quality of finished product and mold life will be affected. Common guide rail types are as follows:
① When W < 150 mm, use a rectangular pressure strip (Figure 5-15);

 

Figure 5-15 Sliding guide in general
② When 150 ≤ W ≤ 350 mm, create a single guide rail groove in the runner (Figure 5-16);

 

Figure 5-16 Design of a slide guide
③ When W > 350 mm, create two guide rail grooves in runner. When W/H > 5, add a T-slot in the middle (Figure 5-17);

 

Figure 5-17 Design of two slide guides

④ When two runners share a pressure strip, runner pressure strip must be positioned to ensure runner accuracy (Figure 5-18);

 

Figure 5-18 Positioning of common row pressure strip
⑤ T-slot guide rail type:

 

It adopts "T"-shaped groove and is installed inside runner. It is generally used in occasions with smaller space, such as runner inside runner.