Emergency Safety Siren Fastener Redesign

Replacement of an Expensive and Unnecessary Patch Leads to a 63% Reduction in Fastener Costs and a $10,000 Saving


During an engineering line review of a customer’s facility, the Field team noticed a commonly used, but often unnecessary and expensive fastening method.

The customer was purchasing and using a hex washer head machine screw with Plastisol under the head and a nylon locking patch. Although the patch is designed to provide secondary locking and safety, the design of the fastener did not allow for full utilization of the patch with only one thread of the patch engaging the nut member.

Field’s customer had been ordering the part this way for the last several years and since it hadn’t raised any red flags, no one in the organization thought twice about the design.


Field identified a hole depth that would allow for an increased fastener length. The Field team proposed keeping the Plastisol under the head but increasing the length of the fastener and removed the nylon locking patch.

The proposed fastener increased thread engagement, allowing for a higher breakaway torque and a more consistent and secure joint. The increased thread engagement resulted in higher failure torque and raised the safety margin.


Field’s validated solution eliminated the need for the $.10 patch and yielded significant cost savings while also increasing thread engagement and reduced lead times.  Engineers are likely to use patches to build fastening redundancy into the design, but in most instances, Field can recommend a more effective and less expensive fastening process.

Savings are based on a buy quantity of 100,000 pieces:

  • Original fastener cost: $27,000
  • Recommended faster cost: $17,000

Total Cost Savings with Field: $10,000