2 Ways to Ensure a Tamper Resistant Metric Fastener

Tamper-proof screws are designed to prevent the dismantling of the products they hold together for safety and/or security reasons. Design developments have made it both difficult to unscrew some fasteners, and easier to determine if a screw has been interfered with. These “tamper-resistant” and “tamper-evident” options have an important place in making products such as electronics, safety devices, security systems, etc., safer, more secure, and less susceptible to vandalism and unauthorized “adjustments.”

metric fastenerThe Tamper Resistant Design

Tamper-resistant screws are labeled as such, because their unconventional drive slots require specialized tools to engage and turn them. Holes, notches, and odd geometric shapes are commonly used as drive slots, and can only be driven with their corresponding tools. The theory is that thieves and vandals may keep slotted and Phillips screwdrivers among their burglary tools as a matter of course, but they are unlikely to have access to spanner or Torx drivers when the opportunity for malfeasance arises.

While the special drivers typically are not included in standard drive sets, they are widely available. This makes most tamper-resistant screws appropriate only in low-risk, and low-value applications.

A Custom Approach to a Tamper-Proof Design

Manufacturers have worked to make metric screws nearly tamper-proof by developing proprietary slots and drivers, going so far as to require driver purchasers to submit affidavits outlining their intended use of the product. Many of these designs include a solid pin within the drive slot, necessitating the use of a tool with a corresponding hole to loosen them. Others have created their screws so the head shears off when they reach a specific torque, leaving them inaccessible by any driver.

Evidence of Metric Screw Tampering

Manufacturers and builders may not be able to guarantee that their metric screws cannot be loosened, but they can make sure producers and maintenance professionals know if and when tampering has taken place by using a commercially available sealant. Here’s how:

  1. Tighten the screw to the desired torque.
  2. Apply the brightly colored and black-light fluorescent sealant to the screw head, encasing it against the work material. Popular brands include Cross-Check and Torque Seal, which come in pen and tube dispensers.
  3. In a few seconds, the sealant will harden to a brittle shell.
  4. A broken seal indicates the fastener has been tampered with or has otherwise come out of torque through vibratory loosening, material weakening, or unauthorized access. On consumer products, a broken seal may be cause for voiding a warranty.

Mr. Metric has the answers to your security fastener questions and needs.  Shop our wide selection of metric tamper-resistant screws in a variety of head styles for sheet metal, machining, and self-drilling applications. If you need additional help, our customer service pros can help you choose the security screws to best serve you and mitigate the risk of theft, damage, and injury.

About the author

Mr. Metric is the spokesperson for www.mrmetric.com, an online store for metric fasteners. Get $7.50 flat shipping with no minimum orders, plus advice and best practices for using metric fasteners in any application.

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