injection molding slider

Injection Molding Slider Design: Enhancing Molding Capabilities with Side Action

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The injection molding slider is a crucial component in the world of injection molding, where precision and versatility are essential to meet the demands of complex and intricate parts. It takes center stage in modern molding processes, enabling the production of intricate features and undercuts that traditional molds cannot achieve. This article delves into the concept of the injection molding slider, exploring its purpose and highlighting its unique features that make it an indispensable tool in today’s molding industry.

Understanding Injection Molding Slider

An injection molding slider, also known as a side-action or side-core, is a specialized component in injection molding that enables the production of complex and intricate features in molded parts. It operates perpendicular to the mold’s opening and closing direction and is used to create undercuts, threads, holes, and other intricate shapes that cannot be achieved with a standard two-part mold.

Injection Mold Sliders Work Principle

Injection molding sliders work by employing a side-action mechanism to produce intricate and complex features in molded parts. When the mold closes, the slider is initially in a retracted position. As the injection process begins, plastic material is injected into the mold cavity, filling all the spaces except those blocked by the slider. Once the plastic material cools and solidifies, the mold opens, and the ejection system pushes the main part out.


During the ejection, the slider moves into action, creating the desired undercuts or intricate features in the part. The independent movement of the slider allows it to interact with specific areas of the mold, achieving precise molding and intricate geometries.

Types of Injection Molding Sliders

There are several types of injection molding sliders, each designed to address specific molding requirements and achieve distinct features in the final product. Some common types include:

Straight Pull Sliders:

These sliders move linearly and are ideal for creating simple undercuts or side holes in the molded part.

Inclined Sliders:

Inclined sliders are used to mold parts with angled undercuts or features, providing greater design flexibility.

Lifter Sliders:

Lifter sliders are used to produce complex shapes or features that require lifting the molded part from the core.

Rotating Sliders:

These sliders rotate during the ejection process, allowing for the creation of threads or other rotational features in the part.

Hydraulic Sliders:

Hydraulic sliders use hydraulic cylinders for actuation, providing precise control over the slider’s movement and allowing for intricate designs.

Electric Sliders:

Electric sliders use electric motors for movement, offering energy efficiency and smooth operation.


The selection of the appropriate slider type depends on the specific design requirements, complexity of the part, and production considerations. By utilizing the right type of injection molding slider, manufacturers can achieve remarkable design possibilities and deliver high-quality molded parts that meet the demands of diverse industries and applications.

Injection Molding Slider Design Rules

Designing an effective injection molding slider involves careful consideration of several key factors and adherence to specific design rules. Here are some essential guidelines to ensure a successful slider design:

Undercut Analysis

Identify the required undercuts in the part design and determine the type of slider needed to create those features.

Slider Actuation

Select the appropriate actuation method for the slider, such as mechanical, hydraulic, or electric, based on the molding process and part complexity.

Material Selection

Choose high-quality materials for the slider components to withstand the stresses and wear associated with repeated movement during the molding process.

Slider Size and Shape

Optimize the size and shape of the slider to minimize interference with other mold components and ensure smooth and efficient movement.


Incorporate proper lubrication points to reduce friction and extend the lifespan of the slider components.

Cooling Channels

Integrate cooling channels into the slider design to manage the heat generated during repeated molding cycles.

Ejector System

Coordinate the slider movement with the mold’s ejector system to ensure the smooth ejection of the molded parts.

Preventing Binding

Implement features to prevent the slider from binding or sticking during movement, ensuring consistent and precise operation.

Mold Venting

Ensure proper mold venting to prevent air entrapment and achieve high-quality parts.

Testing and Validation

Conduct thorough testing and validation of the slider design to identify any potential issues and make necessary adjustments.


By following these design rules and guidelines, injection molders can effectively incorporate sliders into their mold designs, unlocking the potential to produce intricate and complex molded parts with superior precision and efficiency.

Common Challenges and Troubleshooting of Injection Molding Slider

Slider Sticking or Binding

Sliders may experience sticking or binding during movement, leading to production issues and potential damage to the mold or part. This can be caused by inadequate lubrication, misalignment, or excessive friction. Regular maintenance and proper lubrication can help prevent sticking.

Incomplete Part Formation

If the slider does not move correctly or fails to reach its designated position, it can result in incomplete part formation. Check for issues with the actuation mechanism, guide system, or interlocking mechanisms, and adjust as necessary.

Part Ejection Problems

Sliders play a critical role in part ejection. If the slider does not retract properly or has insufficient force, it can lead to difficulties in ejecting the part from the mold. Verify the actuation mechanism and lifter force to ensure smooth part ejection.

Wear and Damage

Frequent movement and contact with the mold can cause wear and damage to the slider components over time. Regular inspection and replacement of worn parts are essential to maintain slider performance.

Cooling and Thermal Issues

Sliders can generate heat during operation, impacting both the mold and part. Proper cooling channels and cooling management are necessary to prevent overheating and maintain dimensional stability.

Misalignment and Tolerance Issues

Slider misalignment or inadequate tolerances can result in improper part formation or damage to the mold. Check for alignment issues and ensure proper fit and clearance between slider components and the mold.

Interference with Other Mold Components

Sliders should be designed to avoid interference with other mold components during movement. Analyze the mold design to ensure smooth and unobstructed slider operation.

Mechanical Failures

Mechanical failures in the actuation system or slider components can cause issues during the molding process. Regularly inspect and maintain all mechanical parts to prevent failures.

Material and Coating Selection

Inappropriate material selection for slider components or inadequate coatings can lead to premature wear or sticking. Choose materials and coatings that can withstand the demands of the molding process.

Injection Molding Process Parameters

Issues with the injection molding process, such as temperature, pressure, or cycle time, can affect slider performance. Adjust process parameters as needed to optimize slider operation.


By addressing these common challenges and implementing effective troubleshooting measures, mold designers and operators can ensure smooth and efficient operation of injection molding sliders, leading to high-quality molded parts and improved production efficiency.

Alternatives to Mold Lifters

There are several alternatives to mold sliders for creating complex features and undercuts in injection molding. Some common alternatives include:

Side Actions or Core Pulls

Side actions or core pulls are movable mold components that achieve similar results to sliders. They move perpendicularly to the mold opening direction to create undercuts and internal features in the molded part.

Collapsible Cores:

Collapsible cores, also known as collapsible cores or collapsible molds, are specialized cores that collapse or retract after molding to allow the easy ejection of parts with complex internal geometries.

Rotating Molds:

Rotating molds, also known as rotating cores or rotating mechanisms, rotate during the ejection process to release parts with intricate internal features, such as threads or helical shapes.

Insert Molding:

Insert molding involves placing pre-fabricated inserts or components into the mold cavity before injection. This technique allows for the creation of complex parts by molding around the inserted objects.

Family Molds:

Family molds are multi-cavity molds that produce multiple parts in a single shot. By combining different part designs in the same mold, family molds can achieve complex assemblies in a cost-effective manner.

Core-Out Molding:

Core-out molding involves removing a core from the molded part after injection. This method is used for creating hollow parts with internal undercuts or complex shapes.

Thread Molding:

Thread molding is a specialized technique for creating threads in molded parts without the need for sliders or rotating molds. It uses special thread-forming inserts or cores to produce threads during the injection molding process.


The choice of an alternative method depends on the specific part design requirements, production volume, and the complexity of the features needed. Mold designers and engineers will consider various factors to select the most suitable alternative to achieve the desired part design and functionality.


In summary, injection molding sliders revolutionize product design and enable precise, complex molded parts. Embracing their capabilities allows manufacturers to stay innovative and meet customer demands effectively. As a leading China custom injection molding manufacturer, Zhongde is committed to delivering high-quality solutions tailored to your specific needs.

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