26 May 2023

What is a plastic hinge?

In injection molding, a plastic hinge refers to a specialized feature designed within a plastic part to provide flexibility and allow rotational movement. The plastic hinge design allows it to endure repeated cycles of bending or flexing without causing permanent deformation or failure of the part. Using the inherent elasticity and flexibility of certain plastic materials, such as polypropylene or polyethylene, plastic hinges allow for rotation within a part without inserting another material. This functional and cost-effective mechanism within injection-molded products offers enhanced versatility and durability.

plastic hinge used ti keep a bottle cap togethert

How do you make a plastic hinge?

When someone designs a plastic hinge onto an injection molded part, the molder needs to know how to make a plastic hinge. In injection molding, molten plastic fills a mold in the shape of the final product. For a hinge, the mold must have a thin section that is narrow enough to allow flexibility within the material but still thick enough to avoid breaking or wearing out prematurely.  

What is the design of a plastic hinge?

The design of a plastic hinge involves incorporating a specific geometry and dimensions into a plastic part to enable flexibility and rotational movement. It typically includes thin sections or living hinges strategically placed within the part, allowing it to bend or pivot without permanent deformation. The hinge design ensures that the plastic material used in injection molding can endure repeated cycles of flexing while maintaining structural integrity and functionality.

How do you fix a plastic hinge?

Fixing a plastic hinge typically involves assessing the nature and extent of the damage. If the hinge is cracked or broken, it may be repaired using techniques such as adhesive bonding or plastic welding, depending on the type of plastic used. Reinforcing the hinge with additional material or inserting metal pins can also provide added strength. In some cases, if the damage is severe or irreparable, replacing the entire plastic hinge with a new one might be necessary.

plastic hinge on a ring box

Common applications for plastic hinges

There are many applications for plastic hinges, including:

  1. Flip-top containers: Small plastic hinges are commonly used in flip-top containers, such as cosmetic cases, toiletry containers, or food packaging. These hinges allow the lid to open and close easily while maintaining a secure closure.
  2. Electronic device enclosures: Many electronic devices, such as laptops, tablets, and smartphones, utilize plastic hinges to enable the opening and closing of the device. These hinges provide flexibility and durability for repeated use, allowing users to access the internal components.
  3. Automotive components: Plastic hinges find application in various automotive components, such as glove box lids, center console compartments, and sun visors. They provide smooth and reliable movement while ensuring secure closure and easy access to storage compartments.

People use other applications in furniture, medical equipment, packaging, toys, kitchen appliances, etc.

Advantages of plastic hinges

Plastic hinges offer several advantages, making them popular in various applications:

  1. Plastic hinges are lightweight, contributing to overall weight reduction in products, especially when compared to metal hinges.
  2. Plastic hinges are corrosion-resistant, eliminating concerns about rust or degradation over time. They can be molded into complex shapes, allowing versatile and customized designs to meet specific application requirements. Plastic hinges provide excellent flexibility, enabling repetitive opening and closing without losing structural integrity.
  3. Plastic hinges are cost-effective, making them a cost-efficient choice for mass production.
  4. Plastic hinges offer enhanced safety as they are non-conductive, reducing the risk of electrical hazards and making them suitable for electrical and electronic applications.

plastic hinge used as a medicine container

Rex Plastics and plastic hinges

Rex Plastics has many years of experience in injection molding, creating parts for a wide variety of applications that utilize efficient concepts such as plastic hinges. Read our testimonials, or reach out to us for a quote today!