Design Dilemma: detent hinge or free swinging hinge?

Does your cabinet design require holding a door or access panel open? If so, did you know you have two options? Use a traditional gas spring along with a free-swinging hinge, or consider a detent hinge. Which do you choose? Rob Bowen, Southco global busin

A detent hinge combines two products in one. It permanently installs to the door or frame to provide smooth hinging action. Plus, its detent feature holds doors opened and closed at certain positions without a secondary mechanical support like a gas spring. Some detent hinges hold doors at pre-set positions. Others allow you to adjust the door swing to your specifications.

A variety of detent hinges are available with pre-set detents at various angles, commonly at 80 degrees, 115 degrees, 120 degrees, 150 degrees and 170 degrees. The hinges also offer varying degrees of detent strength. The detent hinges can be designed to hold a door open at any desired angle, even multiple angles.

In addition, these hinges feature a -10 degrees detent angle, holding the door tightly against the frame. This not only eliminates rattle, but in some cases can eliminate the need for a latch. In this application, a single detent hinge serves three functions.

Detent hinges function using a metal or an elastomer spring component that exerts a force inside the hinge, providing the detent. The detent mechanism is housed and hidden inside the hinge.

There are a number of advantages to designing-in a detent hinge. First, they provide hands-free access. The door remains in a fixed, open position, without extra hardware taking up room inside the enclosure or cabinet. This is a tremendous advantage when servicing is required. Secondly, they offer a variety of positioning torques.

Detent hinges come in different positioning angles to meet various application needs. Designers can choose the angle that offers the most access to a cabinet or enclosure within the framework of the application. What is more, they have a low installation costs. Designers only need to install one component-the detent hinge-as opposed to a hinge and a gas spring, or in some cases, a third component – the latch.

And, snap-on covers on some hinges conceal mounting hardware, enhancing the overall appearance, while providing tamper-resistance and protection from dirt, grit and other contaminants.

A textured black or matte finish gives a contemporary, sleek look. High-quality materials offer corrosion and UV-resistance. Most hinges can also be customised to the colour requirements of the designer.

Depending on the type of detent hinge, radial ultimate load per hinge can be as high as 2600N. Axial ultimate load can be 1800N per hinge. Cycle life extends to 20,000 cycles.

About Gas Springs

Gas springs are pressurised by inert gas or hydraulic fluid. They typically work in conjunction with standard, free-swinging hinges, and install on the inside of a door or panel. They consist of a sealed cylinder containing a rod, tube, piston, seal, and end attachments. Most gas springs are sealed with a rubber seal which tightly hugs the piston rod to prevent leakage and extend the life of the spring.

Some gas springs control the opening or swing of a heavy door, and ensure a constant swing speed. This prevents a door from slamming shut or swinging wildly open. In lighter duty applications, simple struts can hold doors or panels open. These non-gas assisted cylinders also require a free-swinging hinge.

So what are the advantages to using a gas spring and free-swinging hinge? First, gas springs are more suitable for rigorous applications. They can lift, lower and position heavy, cumbersome loads, more easily. Varying stroke, compressed and extended lengths give the designer a lot of options depending on the specifics of the design. Extension forces vary, even up to 1200N. Some manufacturers also offer custom lengths and sizes.

Installation is generally easy, but there are more parts to install: the hinge and gas spring. One caveat: the gas spring must be mounted with the rod end down to keep the fluid closest to the seal for maximum dampening at the end of a stroke.

A gas spring usually hides behind a door or panel. Depending on the application, the hinge can be shown or hidden, depending on your application design.

Gas springs are commonly found on applications in the automotive, medical, marine and industrial machine industries.

Additional Design Considerations

The larger the door or panel, the greater the force required to hold it open. Detent hinges are ideal for light- and medium-weight applications. For heavier duty applications, use a hinge with a gas spring since it is designed to carry greater loads.

If the application is exposed to high wind and other harsh conditions, a heavier-duty detent hinge, or a hinge and gas spring should be used to meet your force requirements. Consider detent hinges for light- and medium-duty outdoor applications. Use of corrosion and UV resistant plastics and snap-on covers protect the hinge against the elements and other contaminants.

Often, total Installed costs determine the access hardware you select. While it may appear cheaper to buy a pair of hinges and gas springs, it often costs more money to install more components. If the hinge is the last component you consider in your design, you might not have enough space inside the cabinet or enclosure to mount a strut or gas spring. Consider a detent hinge that mounts on the outside, saving space on the inside.

Finally, bear in mind the finish of the hinge. A detent hinge with a textured black finish or in a custom colour, can provide a sleek, contemporary look to your application.

Information: Southco Tel: 01452 715400