Coiled springs provide smooth, reliable hinge action

The use of Spirol coiled springs in hinged cosmetic powder compacts is demonstrating major advantages over traditional hinges in terms of cost and durability. In an industry where product quality is vital but margins small, the need to eliminate product failures is taking on more and more significance with cosmetic compact manufacturers.

Spirol Industries is now supplying coil pins for this application, demonstrating high levels of user resilience. Previously the practice was to design misalignment into the holes to create a friction hinge. This was so that the lid of the compact could be held open for display purposes and also to create a smooth hinge action.

However, the use of Spirol Series 550 coiled springs pin simplifies the design, as misalignment of the inner and outer case to provide friction is no longer necessary. By eliminating this requirement, not only is the design and production process simplified, but also the risk of cracking, caused by induced stresses, is removed. This significantly reduces scrap during manufacturing and failure during use.

Improved hinge control

Series 550 coiled spring pins have now become the fastener of choice because they exert uniform radial spring forces that distribute stress uniformly. This results in a controlled hinge movement over a long period of time and this movement is achieved with wider tolerances and lower moulding costs than with the alternative approach of using a solid pin or cut wire.

Spirol typically manufactures series 550 coiled spring pins in work-hardened nickel stainless steel gardes AISI 302/304. The pins used in the application are normally either 1.2 or 1.5mm in diameter and, when coupled with the automatic HC pin insertion machine, productivity is being increased as a result of reduced assembly times.

For more information on coiled pins, contact Spirol Industries Ltd.