Although springs are simple mechanisms, they perform important functions in many applications, so it is important that they are carefully designed to create the right amount of force. Engineers also need to consider the conditions that a spring will be operating under when it is fitted to a final product.
If the spring is located in the engine bay of a car, it may be exposed to dirt and a wide range of temperatures. If the spring is installed on a trampoline, it needs to be able to bear the impact of repeated jumping. Variables like this will be determining factors when considering the kinds of material, configuration, and size for the spring design.
When designing a spring, engineers also have to consider the production tools that will be available and the scale of manufacturing in the production plant. Materials need to be chosen not only for their durability but also for their cost effectiveness. When a custom spring is designed, manufacturers will typically create one or several prototypes to make sure that their factory equipment is being used efficiently and to have a working model that can be tested in a final product.
Once all of the kinks in the production process are worked out, the custom spring is created in whatever quantity has been ordered. Obviously the cost goes down if a large number of springs are produced, and manufacturers will have a minimum number that have to be ordered to make production profitable from a business standpoint.
Before spring design can begin, engineers must be supplied with the specifications for the project and an assembly drawing to show them how the spring will be used with other components. This tells them what role the functionality of the spring plays and what size constraints they will have to design it to work under.
The diameter of these springs could vary greatly depending on the application, from as small as 1mm to as large as several inches. If a jewelry company is going to release a new lineup of wrist watches, for example, they will require extremely tiny springs that can fit within a watch’s small body.
Spring Design Informational Video