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Using Thread Forming Screws to Fight Loosening Fasteners

Thread forming screws are a great way to combat a problem that many of us know all too well: loosening fasteners. Loosening fasteners is a problem that arises on all sorts of products and applications. There can be many causes behind loosening fasteners.

To identify what is causing the loosening and how it can be stopped, the fastener’s function and its interaction with fastener threads need to be analyzed. It is important to find out what stresses the fastener is subject to in order to best determine what solution will prevent a particular fastener from loosening.

During tightening, friction is introduced in the fastener thread and also in bearing areas. Strangely enough, this friction should be what prevents the need for thread forming screws. When this friction fails to keep the fastener tight, issues with the joint, external forces or dynamic forces may be where the issue is stemming from.

In a perfect world, the joint alone would withstand dynamic forces and prevent fasteners from loosening up. To keep fasteners from loosening, the design should work to prevent sliding of the assembled parts. However, a loosening fastener is usually not the result of static forces alone. Many loose fasteners are the result of vibration that occurs during transportation after production.

External, static and dynamic forces need to be taken into consideration during the design process to ensure that the joint can perform at a sustainable level after being introduced to any of these forces. One way to prevent the loosening of fasteners is by utilizing thread forming screws.

By eliminating play in the threads, thread forming screws will prevent loosening under dynamic loads (vibration). Normally there is some allowance between the mating threads of screws and nuts. Thread forming screws, however, form their own mating internal thread when being driven into the work piece and do not have any thread play. Even in the case of intense vibrations of the assembled parts, the thread flanks can’t slide against each other. The existing thread friction is fully maintained, thereby eliminating additional locking devices. The vibration resistance is maintained even after disassembling and reassembling.

Thread forming screws are always used without nuts either in blind hole assemblies or in through hole assemblies. Thread forming screws may be used in low carbon steel, light alloy metals and most plastics although different thread styles are used for each type of material. Pilot hole sizes are critical to the performance of the thread forming screw

There are many solutions to fix all loosening fasteners. Using thread forming screws is just one of many ways to prevent the loosening of screws with fastener technology.

To learn more about using thread forming screws, contact us at ProvenProductivity@bossard.com.

Using Thread Forming Screws to Fight Loosening Fasteners by
May 07, 2014

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