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How to design living hinges for injection molding or 3D printing

Views: 12     Author: Site Editor     Publish Time: 2022-02-22      Origin: Site

People who have worked with consumer electronics know about living hings. You find them in a variety of components - attached bottle caps, clamshell packaging, electronic cases, and name to few. They are easy to manufacture, low cost along with low friction - indeed an awesome choice!

A living hinge is a work like connector between the two thin sections of plastic and with the same materials as the sections. And the sections are fabricated with 3d printing or injection molding. They are often known as piano or continuous hinge. Lets understand the topic briefly by exploring it. As the living hinge is made of flexible polypropylene so it can rotate on axis 180 degrees or potentially for millions of cycles without any breaks. And the bottle cap of water bottles is the best example of a living hinge.

How Are Living Hinges Created?

Firstly it should be designed prototype then manufacture. CAD is used for designing and CNC Machining or injection molding is done for Prototyping. Not everyone can do CNC machine prototype. Only bonerapid have the ability to accomplish the task via Creative mechanisms. Though, 3d printing is also done but this method has some limitations and mass production is done only by injection molding.

Types of the living hinge

Majority living hinges are tab-like joints yet complex designs also exist between sections. These are types…

Flat hinge:

A single tab which connects two rigid sections and has capacity to bend up to 180 degrees

Double hinge:

A two-part hinge which is capable for a bend of up to 360 degrees

Bi-stable / butterfly hinge:

Bi-stable and butterfly hinges, in “flip-top” bottle caps, for instance, can rest in either the open or closed position

Advantages of living hinges

Living hinges have importance as they work like a connector between two rigid sections. Here are some advantages…

Reduced inventory

Low cost



Injection molding living hinges

Years have passed since the living hinges are created with fabricated plastic parts via injection molding process. Living hinges are considered perfect for small connectors and difficult to maintain in very large parts as they are prone to breaks due to tensile strength. Injection molding is the best way to produce living hinges.

Because injection molding is the cheapest way to create living hinges in bulk quantity. Its finish is also better than CNC Prototype because it is worth the value to have the prototype close to the real one.

If you want living hinges designed via injection molding polypropylene or polyethylene — these are steps to follow.

Thickness of living hinges should be 0.3 mm.

Living hinge length should be 1.5 mm

In outside bend radius should be 0.75 mm

Owing to its toughness and ductility polypropylene is considered one of the best material choices for in well designed injection molding PP with life flexes.

Polyethylene is the second wanted material for this purpose after polypropylene.

Besides,flow rate and gate placement affect the injection molding process for living hinges. But we being a top successful injection company would control these parameters and make your goals possible.

3D printing living hinges

Thanks to the invention of injection molding machines, the existence of living hinges has come. It adds more strength and durability to hinges.

3D printing has become a popular form to create plenty of strong prototypes of hinges. When prototypes of hinges are produced via 3d printing, print orientation plays an important role e.g, width which should not be too short, length should walk through the go-axis while printing.

If the hinge is bent along the layer lines it will break Quickly as compared to across the layer line. If the hinges are produced via 3d printing they should be more strong and durable than the molding process as they are less flexible.

If the hinges are produced through 3d printing these points should adhere…

If you want layer by layer hinges you should place the parts oriented.

The thickness of the hinges should be about 0.6 mm to avoid any thickness issues.

In the outside bend 1.5 mm radius should be added.

Living hinge materials

Living hinges are made from parent materials like polypropylene. polypropylene is considered one of the best materials in injection molding for living hinges. It is also used as a substitute. And the best material for living hinges is nylons, be it FDM or SLS printing.

Living hinge applications

In our daily life we are struck by the parts known as the living hinge and examples are a lot of them. Let us discuss some of the many for further information.

Shampoo bottle lids

Dental floss boxes

Condiment bottle lids

Makeup compacts

Storage containers


What Are The Performance Characteristics Of Living Hinges?


Due to their elegant nature, living hinges are very eye-catching with smooth curves.


The simplicity of the living hinge makes it most perfect for all industries with novel solutions with 3d printing and injection molding.

Chemical Degradation

As they are made with plastic so there is no possibility to degrade, they will look like metal hinges.


They are very Economical and would not cost you a penny. They are very cheap and produced in bulk which further reduces the cost as well.


They are very strong and durable because of the absence of parts. They are single so they are strong but would not support a heavy burden.


Their axis rotation capacities make them the most loving hinges in all industries.


They face no friction which gives them superiority over traditional hinges.

Life span

If designed and manufactured properly they last for too long and will not wear and tear in any case.


As they are lightweight and they do not support maintenance and care in any condition.

Range of Motion

Living hinges have the ability to rotate on an axis at 180 degrees. And some rotate at 90 degrees.


Plastic as we know has a low melting point.


Living hinges have limited ability to bear load so this is a limitation.

Why Choose Boenrapid?

Although it seems difficult to many people, yet our expert engineers plus designers team know the exact prototype and where the living hinge is located. Living hinges after Prototyping is our speciality.

Want to make your own prototypes with a living hinge? Contact Boenrapid for further information and for the next project of injection molding and 3d printing.

If you're looking for a well worth company for your next project to see our work sample, <a href="" \h"="">please visit our request page  and submit a form, our sincere team will catch you as soon as possible! We will help you to take your product to the next level.





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