Switched-on sourcing

4most 1Managing director of 4most Electronics, Alan Cook, lists his top tips to ensure buyers make ‘switched-on’ decisions when sourcing switches.

Market trends in the human-machine-interface world are being driven towards tablet style touch screens. Product marketing departments regard this form of control interface as a major selling feature much desired by end customers, but touch screens can have major drawbacks in many applications. Depending on the end-use environment, there may be costs associated with a bespoke design, ruggedisation, waterproofing, operation by gloved hands, illumination and tactile response to actuation.

Switch solutions
The humble electromechanical switch and rotary encoder are therefore far from outmoded. In fact, they are still the preferred HMI solution for many applications such as those in white goods, automotive, aerospace, medical, IT, audio or broadcast and industrial systems.

Most electromechanical switches come in the form of push button, rotary, toggle and slide actuation. Buyers have a lot of choice, with options of number, material, change-over function and current and voltage ratings. They may also want to consider waterproofing, illumination, actuation force, or proof against electrostatic discharge in medical and industrial applications. Finally, they should consider the various mounting options available and the number of operations required during the life of the end-product.

Looking specifically at rotary products, it’s worth noting that rotary encoders are now widely used instead of rotary switches as they offer greater flexibility and multi-function programming. Rotary encoders are commonly found in audio and automotive applications, as well as other applications with similar function, illumination, ruggedisation and operational life requirements.

Problem solving
With so many functional, operational and environmental considerations, working with a specialist supplier is a good idea. Choose a distributor with sufficient product knowledge and specialisation to understand and assist selection as early in the design process as possible.

Involve design engineers in dialogue with the supplier at the beginning of a project to ensure a cost-effective component will be readily available and ensure the supplier has a flexible approach to problem solving.
A good supplier will have the depth of product available to offer alternatives when necessary and ideally, will offer semi-custom and custom solutions, as well as providing in-house technical support should the need arise.

The chosen supplier should be able to support production requirements, as well as offering call-off order and buffer stock facilities. Ensure suppliers can meet any lead-time requirements and work pro-actively to manage the life-cycle of the end-product. Suppliers should provide early warning if a switch is due to become obsolete or is subject to any changes within the production time scale.

Finally, look for an active field support program and ensure samples are available. It’s vital to see and feel any switch that will become an important component in equipment. After all, this is the part that the end customer sees and touches and it can give enhanced perceived value to the end-product.