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We Can Design, CNC Cut, and/or Injection Mold Living Hinge Prototypes For Your Project

We have a proprietary CNC process to cut polypropylene plastic into functional living hinge prototypes. This is useful for design iterations and production of small order sizes (1-10 parts). The results are amazing.

We design and manufacture injection mold tools for larger order sizes (100-1000 parts) where quantity and time efficiencies make injection molding more attractive for living hinge prototypes than machining. 

Living Hinge Prototypes Machined from Polypropylene (PP)

 What is a Living Hinge?

A living hinge is a thin section of plastic that acts as a connection between two larger plastic sections. Typically the larger plastic pieces and the living hinge "bridge" will be made of one continuous piece of plastic. Since it is very thin and typically made from flexible polypropylene, the living hinge is also able to rotate about one axis 180 degrees or more - potentially for millions of cycles without breaking. The bottle cap on a ketchup bottle is perhaps the most well known example of a living hinge. For a comprehensive discussion about living hinges read here

polypropylene (PP) business card holder prototype hinge_view
polypropylene (PP) business card holder prototype front_view
polypropylene (PP) business card holder prototype snap_view

Creative Mechanisms Can Do What Many Consider Impossible! 

CNC Machine Polypropylene Sheet Material Into Prototype Living Hinges with Accuracy up to 5/1000ths of an Inch

Polypropylene Living Hinge Prototypes

We CNC machine living-hinged prototypes out of a single piece of polypropylene using a proprietary technique that we developed in-house at Creative Mechanisms. We can design and cut novel living hinge prototypes to extremely exacting specifications (typically .005 of an inch). We machine snaps of various designs into fully-functional prototype models that can open and shut thousands of times without failingThe results are amazing. For many reasons, most engineers believe this is impossible, but we do it routinely.

The ability to CNC Machine living hinges opens up all sorts of new product possibilities across numerous industries, which we would be happy to discuss with you. Our team is collaborative, insightful, and accustomed to working under tight deadlines. We build all sorts of prototypes and take great pleasure in accomplishing what others think is impossible.

Want a free sample? Submit your request and we'll send you one for free. Click here.

polypropylene (PP) business card holder prototype hinge_view
Child Safe Hinge
polypropylene (PP) business card holder prototype hinge_view
Butterfly Hinge (Profile View)
polypropylene (PP) business card holder prototype hinge_view
Butterfly Hinge (Plan View)

Living Hinges, Their Benefits, and the Alternative Options For Prototyping

Hover Over the Icons Below to Learn More About The Specifics of Living Hinge Design

The Benefits of Living Hinges

The Benefit

Living Hinge Materials (polypropylene)

The Materials

Living Hinge Design Process

The Process

Alternatives For Living Hinges (CNC or Injection Mold Tool)

The Alternative

The Benefit of Prototyping Living Hinge Designs in Polypropylene

On the positive side, living hinges do not require maintenance or repair because they only fail when subjected to unnatural conditions. Because they are made from polypropylene plastic there is no possibility of rust as you would have with metal hinges. Additionally, the range of motion is much wider with living hinges than with other types of hinges.

On the negative side, living hinges can only be used for relatively small or lightweight applications. This is because their resistance to tensile and/or shear stresses is limited. The fact that designers must make sure the cross section of the living hinge doesn’t exceed a certain thickness (to allow proper function) limits the possible robustness of a living hinge, making it unsuitable for certain functions. Using a living hinge for a door, for example, would subject it to excessive weight and would quicken its path to failure.

Polypropylene Sheet Stock and Other Options

Polypropylene (PP) is unique in that it is really the only material that can viably be used for living hinge applications. This is a limitation as the designer is restrained by the material properties and capabilities of the material itself. You can read all about Polypropylene here.

It may be possible to use Polyethylene (PE) in some situations. Additives and fillers that can be used are limited based on their propensity to change material properties that are important to the basic functionality of a living hinge. Other common types of engineering grade plastic like ABS or polycarbonate (PC) are unsuitable for living hinge applications. Traditional hinges would be a better fit if project requirements necessitate such a material.

Creating Living Hinges via Automated CNC Machining and/or Injection Mold Tool Creation for Injection Molded Manufacturing

For design verifications and prototyping, there are really two viable options to produce a prototype part with a living hinge:

#1: CNC machining a prototype out of a single piece of polypropylene (PP) sheet stock: For design verifications and prototyping it is quicker and cheaper to cut prototype parts with living hinges out of polypropylene stock material. Many people believe this to be impossible - for a number of reasons - one of which is the tendency of PP to gum up when being precisely machined. Fortunately for us these people are wrong. Polypropylene can in fact be machined into living hinge prototypes. Creative Mechanisms technicians can machine cut very small and precise living hinges of an infinite variety of designs down to 0.005 inch accuracy on our automated multi-tool CNC machine.

#2: Designing and manufacturing an injection mold tool (i.e. a block of aluminum or steel with an internal cavity in the shape of your prototype part): Getting the hinge right in an injection mold tool can be tricky and it is much more expensive to design and build an injection mold tool than it is to cut one or two prototypes on the CNC machine. We recommend this method when you need several hundred to a thousand prototypes for things such as pre-production testing purposes. On such a scale it is much more efficient to injection mold the parts out of the final material than it would be to CNC cut so many of them. Additionally, for sale samples where a couple of hundred prototypes are required, using injection molding is the better option, not only because of the quick turnaround, but also because the finish is better than a CNC cut prototype. This is vital in sale sampling where it is desirable that the prototype looks as close to the final product as possible. Note: even in such a case it is nice to first CNC cut prototypes to make sure the design is properly functional before making the investment in an injection mold tool.

The Alternative to Creating Polypropylene Living Hinge Prototypes with CNC Machines

For large prototype projects (100-1000 unique prototype units) the best option may be to create an injection molding tool and to produce the parts out of the actual material that will be used in production. For more on our capacity to provide this service read here.

For small prototype projects (1-10 unique prototypes units) and iterative design revisions there is really no substitute for our ability to CNC machine polypropylene living hinges out of sheet material. Other options such as 3D printing, making rubber molds and casting in low durometer urethane, cutting a small polypropylene hinge and screwing it into two separate parts, or simply using tape are all an order of magnitude less effective at best, or completely dysfunctional and subject to quick failure at worst.

white polypropylene (PP) pouch living hinge prototype
Butterfly Hinge
polypropylene (PP) living hinge box open
Butterfly Hinge
polypropylene (PP) business card holder prototype hinge_view
Straight Hinge
polypropylene (PP) business card holder prototype hinge_view
Straight Hinge

Contact Creative Mechanisms About Your Living Hinge Project

Request A Quote

Submit your project idea online and let our design engineers evaluate your needs to see if we are the right partner for your next project. 

Call Us

We're here to help. Dial 215-788-4566 to discuss your project and/or to answer any questions you might have.

Email info@creativemechanisms.com

Email Us

Send an email to info@creativemechanisms.com and one of our product specialists will be in touch to assist in your request.


Free Sample

Want a prototype living hinge business card holder all machined out of a single block of polypropylene? Fill out our form and we'll send you one for free!