A thin, flexible plastic section that connects two rigid sections, a “living hinge” is one of the most ingenious functions that can be built into injection molded plastic parts from one mold.
By allowing a plastic product to swivel at a certain point, a living hinge is a way to utilize the same material for the whole part. In effect, two thicker pieces are created to support the hinge, and then the hinge itself is just a thinner section of the same material allowing it to flex.
Although common to spot once you start to look out for them, these low-cost, rather clever additions to a design can remove the burden of attaching conventional hinges post-production, or indeed avoid overmolding to a static hinge. Remarkably, if planned and created currently, they have little wear or friction involved in standard operation and are therefore a popular choice for a wide variety of applications.
The are a few plastic types that mold themselves well to this use, however, we most commonly see polypropylene being utilized since injection molded hinges from this material can have an almost infinite service life reaching several million flexes if designed and created correctly.
Understanding a few basic rules initially, and then critically getting expert advice during the development process is the best recipe for success when planning to roll out a product that uses living hinges; for example, as opposed to having one large hinge of multiple inches, it is far better to replace that with multiple smaller hinges as this reduces stress and pressure and adds longevity.
Developing millions of auto and other parts annually, injection molding stalwarts ADIS Tachov s.r.o. have a team of professionals from the industry who are always on hand to guide and make recommendations on the most sturdy approach, however early or late in the design process you are. Operating dozens of machines capable of handling anything from the minute to the massive, and delivering globally, a phone call to them could be the first step to save you quite monumental time and money.
