Lifters can be further classified into two types: cylindrical pin type lifters (Figure 3) and T-block type lifters (Figure 4).
Of these two types, cylindrical pin type lifters are more widely used in design, mainly because they are easy to manufacture, install, and maintain. T-block type lifters are primarily used for larger products with higher precision requirements. They also require a dedicated T-shaped base (Figure 5) (Figure 6), making manufacturing and fitting more difficult and increasing costs.

 

 

As shown in left figure, lifter is placed in an angled hole in a fixed template, with ejector fitting into hole. When a thrust is applied upwards, pushing ejector a certain distance, it is observed that under forced action of angled hole and thrust, ejector not only moves upwards but also moves a certain distance in direction of lifter's inclination (as shown in positional difference in figure).
During ejection process, because product moves vertically, while lifter not only moves vertically but also moves in opposite direction to dead angle, it can effectively handle dead angle.
Prerequisites: Dimensions of mold plate, mold core, and mold base have been determined. See diagram below for details.
1. Review drawings and analyze them carefully to determine size of dead angle. See diagram.
2. Determine starting point of 0° break surface and its length (as shown in Figure AB). If a 0° break surface is not designed, select point A as starting point of inclined surface of ejector.
3. Using point B as a reference, offset it by a distance, as shown in Figure BC. BC = ejection stroke.
4. Using point C as a reference, offset it by a distance in opposite direction of ejector's movement, as shown in Figure CD. CD = inclined stroke (rounded to the nearest integer) = dead angle size + minimum safety margin greater than or equal to 3mm.
5. Connect DB to obtain angle DBC. This angle is generally a decimal. We take an integer, M". This angle is required lifter of inclined plane. 6. The rest of design can be completed based on structure and requirements described above.
In fact, main purpose of such complex content is to teach us how to calculate lifter of inclined plane. We can simplify it as shown in following diagram:

 

As shown in diagram above, we can derive trigonometric function tgM° = inclined plane stroke / ejection stroke. Finding value of M° is then easy, and it can also be measured directly on drawing.
Points to note regarding lifters: 1) Lifter should generally be below 15 degrees, and angle should be as small as possible. 2) Strength of ejector, lifter, and ejection distance should be coordinated. 3) Consider whether product will stick to ejector, whether positioning and holding measures are used to hold product in place. Following diagram is generally used.

 

Check if lifter head is at wrong angle (to prevent ejector from scraping glue). Also, be careful not to let lifter interfere with other components (such as other lifters, ejector pins, or ribs). Always check this.

 

Safe distance for lifter tripping mechanism is 2-3 degrees, and lifter surface shown should have an inclination of 2-3 degrees.

When product is very deep and there is a lifter on the side, a step should be added to lifter for positioning, as shown in figure below. Another situation is that lifter is on the side of product (product has a certain depth), and there is a relatively deep rib on one side of lifter.

 

When width of ejector body exceeds 50mm, it is called a large lifter.
Considering material costs, machining workload, and mold maintenance, large lifters mostly adopt a split structure. Back slope of ejector body is 1-2 degrees greater than that of ejector guide rod to prevent friction between back of ejector body and punch. Simultaneously, two sides of ejector are designed with matching slopes, generally 3 degrees.
In most cases, round guide rods are used for ease of machining and maintenance. In special cases, square guide rods or a one-piece structure can also be used.
For molds with lifter structures, ejection space should be controlled within 180mm as much as possible, angle of ejector should be controlled within 15 degrees as much as possible, and cross-sectional area of ejector guide rod should be as large as possible to ensure that ejector guide rod does not bend or deform during movement.
When distance between lifters is greater than 120mm and angle of motion of lifters is greater than 10 degrees, it is suitable for molds of equipment with a capacity of 500 tons or more. Sliding block in connection part of lifter base should preferably adopt a rotatable structure to ensure that lifter guide rod will not bend or deform during movement.

A small lifter refers to a core-pulling area that is relatively small. Cooling is generally not designed, and a single-rod guide drive is commonly used. Small lifter is a very common core-pulling mechanism with high usage frequency. It generally has integral and split structures. Lifter structure consists of following components. Split structures mostly use round rods and round sleeves, and sliding blocks also differ. Components similar to integral structure can also be used, with square holes in guide blocks replaced by round holes.
Recommended angle for core pulling with lifter rod is 4, 6, 8, 10, 12, or 15 degrees. Avoid using angles greater than 15 degrees. In special cases where a core-pulling angle greater than 15 degrees must be used, an auxiliary guide mechanism must be designed. Sometimes, lifter core-pulling direction has an angle with parting surface, tilting upwards or downwards. In such cases, upper and lower wear-resistant plates of lifter rod are designed as a single unit, becoming lifter rod guide seat.
For molds with lifter structures, ejection space should be controlled within 180mm as much as possible, angle of lifter should be controlled within 15 degrees as much as possible, and the cross-sectional area of guide rod of lifter should be as large as possible to ensure that guide rod of lifter will not bend or deform during movement.

Notes:
I. Above-mentioned lifters are all rear mold lifters.
II. General design sequence for lifters is as follows (for reference):
1. Determine angle of lifter based on the actual stroke. Common angles are: 3 degrees, 5 degrees, 8 degrees, 10 degrees, and 12 degrees.
2. Determine width of lifter based on width of hook.
3. Determine type of lifter seat (T-type or tube pin type) based on width of lifter.
4. Determine length and width of wear-resistant block based on length and width of lifter. Thickness of wear-resistant block is generally 15mm (see diagram above), and its material is 2510.
5. Typically, lifters are made of 8407 material and require quenching to HRC: 48-52 degrees Celsius. Ordinary lifters use 718H material and require surface nitriding.
III. Because lifters and their mounting bases have a mating relationship, following are some commonly used lifter base types for reference during design.

 

 

Notes:
1. Lifter seats often use a T-slot design, as shown in Figure 1 above. If lifter is very thin, i.e., a T-slot cannot be made, consider designing it as a fixed seat, as shown in Figure 2.
2. All lifter seats use WY718 and must undergo surface nitriding treatment.
3. When designing Lifter, make it as large as possible, within limits of mold design.