All About Springs

metal fabrication is quite unusual as a topic for Sunday lunch at grandma's. On the other hand, its results are all around us. Take springs, for instance. Any mechanical product will have extension or compression springs, such as mattresses, door handles, trampolines, and so on.

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But springs do not grow in trees, regardless or your inner-child imagination. Moreover, did you know there are different types of springs? Keep on reading to find out more.

What Are Extension Springs?

This is a type of spring attached at both ends with eyes and hooks to the other coil-connected components. As they move apart, its job is to pull them back together, storing energy and creating a resistant pulling force.

They are typically used in cars interiors and exteriors, as well as garage door assemblies, farm machinery, vise-grip pliers, and many different toys. Their sizes may vary from very small, inside medical devices, to much larger, inside off-road machinery braking systems.

What Are Compression Springs?

These are the most common springs, offering a great energy storage. Their shape is an open coil designed to oppose compression, often fitted in a hole or placed over a rod. By loading weight, they compress and become shorter, resisting and pushing the load back as they try to return to their original shape.

Most compression springs are a straight metal coil, with a constant diameter throughout the component length. Think about a mattress. There are also conical and barrel springs, with convex and hourglass shapes, which are used in more specialized applications.

How Are Springs Made?

The first step is to shape the wire. First, it needs to be straightened from the round, long stock wire into a spring shape. This process is usually made inside an auto-coiler machine in an industrial scale.

Then, it is time to temper the metal in the furnace, heating it to a constant temperature of 920°C during 30 minutes. At this temperature, the metal will become pale orange.

Now, it is time to quench the springs in a pool of oil, cooling it quickly and effectively transforming the grain structure of the metal. From malleable, the metal will become hard and brittle.

After that, it is time to wash the springs, and temper them again by heating them to 450°C in order to establish the desired ductility in the metal.

Now, the metal fabrication process is finished. If the springs will be used in any machinery or process that demands precision, they will likely be tested for quality control purposes. This is to verify elements such as metal hardness and deformation under a determined force.

The benefits of quality control are twofold: they ensure the consumer that minimum product standards are met, and they also help the manufacturer to identify problems in the manufacturing chain and improve their internal production processes and practices.

Finally, all that is left is to paint, pack, and transport the final product.

Modern factories powder-coat springs with electrostatic guns and cure them at 230°C. Powder-coating is a great finish because it is hard and prevents corrosion. Alternative coating methods are spray-painting, dipping the springs in liquid rubber, and plating them into another metal such as chromium or zinc.

Finishing the springs also allows manufacturers to match the springs to the looks of the machines they sell.