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Choosing Special Fasteners

Nov. 15, 2002
Many fasteners are designed for special functional or material requirements.

Many fasteners are designed for special functional or material requirements.

Design factors to consider when choosing specialty fasteners include:


Communication: Early supplier input will guarantee sufficient lead time to design the fastener, conduct tests, and make necessary alterations.

Underengineering: A purchase should not be made solely on price. The fastener may be improper for the particular application or too frail for the job. Do not specify a single-thread fastener where a multiple thread is necessary. Do not use an existing fastener for an application that requires a specially designed fastener.

Overengineering: Do not request metal that is too heavy for an application, critical tolerances where they are not needed, or oversized nut-and-bolt combinations.

Finish: Choose finish after the supplier studies the problem. Finish hardness should be based on application.

Material: Match the grade of steel to the application. Be particularly aware of gauge thickness.

Fastener function: Clearly specify what the fastener will do when ordering. Be aware of fastener limitations.

Servicing: Before ordering, know if the fastener will be removed. If so, determine how often it will be removed and if special tools will be required.

Assembly techniques: Be sure a requested fastener is compatible with existing automatic assembly equipment. But do not compromise fastener reliability for assembly speed.

Marketing: There may be delays when ordering fasteners made of hard-to-get materials. Order size must be evaluated carefully. Once an order is placed, some suppliers may not be able to handle high-quantity runs on short notice.

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