An injection molding lifter is an important mechanism in the injection molding process. During the ejection stroke progress it slides and pulls the cavity steel away from the undercuts in the die. The injection molding lifters are generally essential for helping in production of complex geometries and undercuts in molded parts.
They also enhance production efficiency through production of complex parts in a single cycle especially for high volume production. Lifters role in injection molding is crucial for achieving high quality products and meeting the desired design and manufacturing requirements.
In this article we are going to look in detail, what an injection mold lifter is and a step to step guide on designing injection mold lifters.
Injection Mold lifter (Image Source: Pinterest)
What is an Injection Mold Lifter?
We have seen that an injection mold lifter is a movable mechanism that is used to lift molded parts off the core side of the mold during the injection process. It is an important component in injection molding as it helps create complex geometries and undercuts in molded parts.
Lifters offer various advantages in lifting the molded part off the core side of the mold during ejection. Below are some of the functionality of lifters:
- Allow for production of intricate parts with undercuts and internal features.
- They help reduce the risk of part damage during ejection enhancing part quality.
- Lifters facilitate manufacture of multiple parts in a single mold improving production efficiency.
- They provide versatility in production through molding of various parts with varying geometries.
Detailed 9-Step Design Guide for Injection Mold Lifters
- Analyze the Part Design
This is the initial step in designing an injection mold lifter. The designers must clearly understand and analyze the part geometry, this involves any undercuts or other intricate features that will need a lifter to ensure smooth part release.
You must also understand the tolerance requirement for the part application including dimensional accuracy and surface finish. Another consideration is the material properties of the part. Evaluate the stiffness, flexibility and shrinkage characteristics to understand how they will influence the design and function of the injection mold lifter.
2. Determine the Lifter Position and Direction
This is the next crucial step in designing injection mold lifters. The lifter’s position is where it is fixed on the mold and the direction is the angle at which it will move. In order to determine the lifter position the following are some considerations to look into. Evaluate the part design to identify areas with undercuts or intricate features that need additional clearance for ejection.
Assess the parting line on the mold which separates the core and cavity halves. It is important to consider how the lifters position and direction interact with the mold ejection system and other components. Some of these components are ejector pin placement, gate and runner design mold venting, core and cavity alignment. Overall this ensures smooth and effective part ejection.
3. Design the Lifter Mechanism
The lifter mechanism is the component that moves the lifter. This is important in ensuring the effectiveness and efficiency of part ejection. There are several lifter mechanisms commonly used, cam, hydraulic, and mechanical.
Cam Mechanism
Cams are used here to convert rotary motion into linear motion, facilitating the required lifting action. This is a simple and cost-effective design and provides accurate control over lifter movement. It is preferred for applications with simple ejection requirements.
Hydraulic Mechanism
These use hydraulic cylinders to provide the force needed for lifting mold components. It is suited for lifting heavy and complex parts due to the high force. It can accommodate a wide range of lifter configurations and movements.
Mechanical Mechanism
It uses interconnected links and levers to transmit motion and force providing the lifting action. Provides versatility in movement and offers reliable performance. When selecting a lifter mechanism it is important to consider the type of mechanism that will work best for the part design.
4. Determine the Lifter Size and Shape
Once the lifter mechanism is designed the next step is determining the injection mold lifter size and shape. This depends on various factors based on part and mold design. The lifter size and shape depend on specific part geometry, parting line and cavity layout and also the ejector system. To ensure optimal lifter effectiveness in injection molding some techniques may be incorporated.
Some of these techniques include comprehensive part analysis, proper integration with the ejection system, optimization of material selection, monitoring, and maintenance. Through utilizing some of these techniques manufacturers can ensure that lifter mechanisms are optimized for effectiveness.
Injection Molding Design (Image Source: Pinterest)
5. Design the Lifter Support Structure
The lifter support structure is the component that supports the lifter in the mold. It is important to consider the mold design and lifter size and shape. Below are some steps to consider when designing the lifter support structure.
Step 1: Identify the Needed Support
It is essential to identify the sections of the lifter that require support. This may include where the lifter may face high stress or force and additional support is needed. By putting these into account the type and amount of support required is determined.
Step 2: Determine the Material
Choose a material for the support structure suitable for the lifter design and injection molding process. The material should be able to withstand the stresses and forces the lifter will encounter during application.
Step 3: Determine the placement of the support structure
This is where the location of the support structure is determined. This depends on the desired requirement of the injection mold lifter design and the injection molding process. The support structure should provide support without affecting the mold or any other component in injection molding.
Step 4: Design the support structure
Here the support structure is designed to provide the needed support to the lifter. The support structure should be strong enough to withstand the forces and stress the lifter will face during operation.
6. Analyze the Lifter Design
The lifter support structure design is analyzed to ensure that it serves its design functionality. Manufacturers need to consider the part design, mold construction, and the lifter’s movement. Evaluate the part design to identify complex features and undercuts that have an impact on lifter design and movement.
It is important to consider how the lifter mechanism will integrate with the mold design and interact with other mold components. Determine the expected movement of the lifter mechanism during the ejection phase of the injection molding process.
Another factor to look into is the force and load analysis where the structural requirements of the lifter mechanism are determined to withstand these forces without deformation. Through analyzing these factors manufacturers can produce a lifter design that enhances effective part ejection.
7. Make Modifications to the Lifter Design
This process is aimed at refining the lifter design to optimize performance and address any issues during the analysis phase. The following are some steps to take into account when modifying the design.
Identify the Issue
It is important to identify the problem with the injection molding lifter design first before making any modifications. This can be achieved by carefully analyzing the lifter’s design. The root cause of the issue should be identified to ensure that the modifications address the problem.
Evaluate Potential Solutions
To find a solution, brainstorming and consultation with experts is necessary. Each solution is evaluated to determine the most feasible and practical solution. It is important to consider the cost, ease of implementation, and impact on the lifter’s performance.
Implement Modifications
Once the best solutions are identified the next phase is implementation of these modifications. These may involve changing the material used, geometry, or manufacturing process.
Test the Modified Design
After implementing the modifications the modified injection mold lifter design is tested to ensure it addresses the issue and the lifter functionality is as desired.
8. Produce The Lifter
Here the lifter is produced according to the finalized design. A variety of manufacturing processes are used to create the lifter. They include Machining, casting, and 3d printing.
Machining
This technique involves the removal of material from the workpiece through the use of cutting tools to achieve desired dimensions and shapes. Machining is suitable for lifter components with precise dimensions and tight tolerances and is used mainly for low-volume production.
Casting
This involves injecting molten material into a mold cavity where it solidifies to form the desired shape of the lifter component. It is highly cost-effective for high-volume production runs and ideal for producing lifter components with complex shapes and intricate features.
3D Printing
Through additive manufacturing, the lifter components are produced layer by layer using computer processes from 3D models. Suitable for the production of highly complex lifter geometry with minimal tooling.
Material Selection
When selecting a material it is important to choose one with high strength and durability to withstand the force and stress encountered during ejection. You need also to consider the wear and corrosion resistance of the material to prevent degradation over time. In addition, ensure that the material can withstand temperature variation in the injection molding process.
9. Test the Lifter
In this stage, tests are performed on the lifter to ensure it works properly and to identify any issues that should be addressed. Below are some of the methods used to test the design of a lifter.
Moldflow Simulation
Moldflow simulation software can simulate the lifter’s movement during injection molding. This technique is normally used in the early stages of the injection mold lifter design process. The software can identify any problem with the lifter design such as improper lifter movement or potential part defect.
Prototype Molding
Developing a prototype mold with the designed lifter can help identify any issue with the lifter’s movement or performance. This helps evaluate quality and functionality.
Mechanical Testing
This is significant for evaluating the lifter’s strength, durability, and wear resistance. Mechanical test results can help identify any potential issues with the lifter’s design.
Injection Mold Design (Image Source: Pinterest)
Conclusion
Designing a lifter for injection molding needs keen attention, careful consideration, and proper following of each step. By considering factors such as part geometry, mold construction, and manufacturing techniques manufacturers can develop lifter mechanisms that optimize performance and part quality. Lifters are essential for producing complex and intricate molded parts.
Lifter’s continuous development contributes to enhanced plastic injection molding and precision in producing complex plastic parts. Continuous learning and adaptation are essential in lifter design practices to stay competitive and ensure success in injection molding.
