How Do We Deal With The Undercut In Injection Molding

Injection molding is a commonly used manufacturing process for producing plastic parts in high volumes. It involves injecting molten plastic material into a mold cavity, where it cools and solidifies to form the desired shape. However, one common issue that can arise in injection molding is the undercut. An undercut is a feature on a part that prevents it from being ejected from the mold in a straight, linear motion. This can lead to complications during the molding process and affect the quality of the final part.

Unaddressed undercuts can cause damage to the mold, increase production time, and result in parts that do not meet quality standards. Therefore, it is crucial to understand how to deal with undercuts in injection molding effectively. In this article, we will discuss several strategies to overcome undercuts and ensure a successful injection molding process.

Identifying Undercuts

Identifying undercuts is the first step in addressing the issue in injection molding. An undercut is any protrusion, indentation, or feature on a part that prevents it from being ejected from the mold in a straight, linear motion. Undercuts can be challenging to detect visually, especially on complex or intricate parts. To identify undercuts accurately, it is recommended to use advanced inspection tools like 3D scanners or CAD software.

Once undercuts have been identified, it is essential to analyze their impact on the molding process. Undercuts can cause problems such as part distortion, mold damage, or production delays. Understanding the extent of the undercuts and their potential consequences will help in developing an effective strategy to deal with them.

Design Modifications

One of the most common ways to address undercuts in injection molding is through design modifications. By altering the part design, it is possible to eliminate or minimize undercuts, making the molding process more straightforward and efficient. Design modifications can include adding draft angles, changing part geometry, or repositioning features to eliminate undercuts.

Draft angles are essential in injection molding as they allow the part to be easily ejected from the mold. By adding draft angles to part features, it becomes easier to release the part from the mold without causing damage. Additionally, changing the part geometry to eliminate sharp corners or complex features can help reduce the likelihood of undercuts. Repositioning features that cause undercuts can also be an effective way to address the issue during the design stage.

Core-Pulling Mechanisms

Core-pulling mechanisms are another effective solution for dealing with undercuts in injection molding. A core-pulling mechanism is a component of the mold that moves independently to release the undercut feature from the part. By using core-pulling mechanisms, it is possible to create parts with complex geometries and undercuts without compromising the molding process.

Core-pulling mechanisms work by using hydraulic or mechanical systems to move a core feature within the mold. When the mold opens, the core-pulling mechanism retracts, allowing the part to be ejected cleanly without any interference from undercuts. Core-pulling mechanisms are ideal for parts with intricate details or features that cannot be modified through design changes.

Overmolding

Overmolding is a technique used in injection molding to address undercuts by creating a part in multiple stages. In overmolding, a base part is first molded, and then a second material is injected over certain areas to create additional features or details. This second material can cover undercuts and create complex geometries that would be difficult to achieve in a single molding stage.

Overmolding is a versatile solution for addressing undercuts as it allows for the creation of multi-material parts with unique properties. By using different materials in the overmolding process, it is possible to achieve specific functionalities or aesthetics that would not be possible with a single material. Overmolding is commonly used in industries such as automotive, consumer electronics, and healthcare to create parts with intricate designs and undercuts.

Tooling Modifications

Tooling modifications are essential in injection molding to address undercuts and ensure a successful molding process. By modifying the mold design or tooling components, it is possible to accommodate undercuts and create parts with complex geometries. Tooling modifications can include adding side-actions, core pins, or sliders to the mold to release undercuts effectively.

Side-actions are components of the mold that move laterally to release undercut features from the part. By adding side-actions to the mold design, it is possible to create parts with multiple levels of undercuts or complex geometries. Core pins are another tooling component that can be used to address undercuts by creating a movable core feature within the mold. By using core pins, it is possible to release undercuts and create parts with intricate details.

In conclusion, dealing with undercuts in injection molding requires a combination of design modifications, core-pulling mechanisms, overmolding techniques, and tooling modifications. By identifying undercuts early in the design stage and implementing appropriate solutions, it is possible to create parts with complex geometries and intricate details without compromising the molding process. Addressing undercuts effectively will lead to shorter production times, reduced costs, and high-quality parts that meet industry standards. By following the strategies discussed in this article, manufacturers can overcome undercuts in injection molding and achieve success in their production processes.