There are over 80 different kinds of pushbuttons, with different sizes and different functions. So, how in the world do you pick the one that’s right for you? In today’s episode we are going to talk about just how you select the right pushbutton for your application. Let’s start understanding pushbuttons.
In today’s world, a single machine often performs multiple functions. Humans control the machine, initiating changes based on work assignments or advancing the machine to the next step of the process. This is where pushbuttons come in. Through pushbuttons, workers can interact with the machine’s operation.
What does a pushbutton do
The term “pushbutton” is used to refer to two different things.
- The first is a specific type of button assembly that you actually push on a panel.
- The second is the general group of components, or mechanical man/machine interface products, which includes: Indicating Lights, Selector Switches, Potentiometers — and pushbuttons — by which people interact with machines.
What to consider when looking at pushbuttons
Size or diameter
The first thing to consider is the size or diameter of button that you are looking for. Typically, a 22mm pushbutton is used in light industrial applications such as machine building, panels, material handling, and conveyors. Whereas a 30mm pushbutton are usually a better fit for heavy industrial applications such as oil & gas, water/wastewater, industrial equipment, and chemical plants.
Style
The next thing that we consider is style. Pushbutton families come in several styles and can be selected to complement the design of your machine. They usually come with either silver or black bezels, which is the color surrounding the operator. Another style option is flush mount, which allows the button to blend into the surface of the machine, or surface mount in which the button stands off the surface of the machine.
Operator type
Next you need to select the operator type. The reason there are so many pushbutton types is because each style provides an answer to a field problem. We can categorize these styles into the following buckets:
- Extended: An exposed button is raised further off the panel than other buttons. Often used for a machine’s most important function, such as “Stop.”
- Flush: The button is flush with its housing. Direct pressure must be applied to actuate flush pushbuttons; they are not easily bumped into changing state. Often used as a START button.
- Selector Switches: These are used when more than one control option is needed (e.g., HAND/OFF/AUTO). Selector switches are usually the preferred pushbutton when a maintained contact is needed.
- Guarded: These take prevention of unwanted operation one step further than flush pushbuttons by having a metal guard around the actuator portion of the button.
- Mushroom and Jumbo Mushroom: These are most often used for Stop and Emergency Stop pushbuttons. Very easy to actuate because they make such a big target.
- Push-Pull operators: These must be physically pushed in or pulled out to change status. Two-position maintained contacts for START/STOP or UP/DOWN. Three-position maintained or momentary for START/STOP/RUN or HAND/OFF/AUTO functions.
- Twist-to-Release: These are maintained contact pushbuttons that you push in and then twist to release. The Twist-to-Release is often used for “Stop” or “Emergency Stop.” The extra effort needed to restart a machine forces a more active decision on the part of the worker.
- Key Release: These are maintained contact pushbuttons that you push in and need a key to release. Often used for safety reasons; for example, to lock off a machine during maintenance.
- Illuminated Pushbutton Lens: Saves space and money by combining the function of a pushbutton and an indicating light. Even though the button contains both an operator and a light, these are actually separate items that have to be wired separately inside. For example, the pushbutton might connect to a starter, while the light is wired to a microchip that reads “the engine is running.”
- Potentiometer: Often used for speed control because turning the dial varies the resistance (ohms).
- Joystick:Mounts in a standard hole size, although space must be left on the panel for the lever action. Because the joystick extends outwards and often corresponds to the direction of movement sought, it is easy and intuitive to use.
- Roto-Push: A combination of a selector switch and a pushbutton in one unit. The outer guard of the pushbutton rotates to two or more positions and provides different contact actions when the pushbutton is either free or pushed-in at each selector position.
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