Fastener options: PEMs, rivet nuts, welding studs

Fastener Options: PEMs, Rivet Nuts, and Welding Studs in Sheet Metal Fabrication

In precision sheet metal fabrication, integrating fasteners directly into the sheet metal is critical for achieving reliable assembly, structural strength, and efficient downstream integration. Selecting the right fastener system depends on several key factors, including:

• Sheet metal thickness

• Load-bearing and torque requirements

• Assembly access (single-side or double-side)

• Long-term corrosion protection

• Required production volume and cost targets

At Rollyu Precision, we collaborate with customers to evaluate fastener types that meet both functional performance and manufacturability requirements — especially across high-precision industries such as medical devices, photonics equipment, semiconductor tools, automation systems, and aerospace assemblies.

In most sheet metal applications, three primary fastener types dominate:

• PEMs (Self-Clinching Fasteners):      Provide strong, permanent threads in thin sheet metal with high load      retention and flush finishes.

• Rivet Nuts (Blind Threaded Inserts): Offer versatile thread reinforcement across a wide range of      material thicknesses, with blind-side installation capability for      difficult-to-access assemblies.

• Welding Studs: Deliver robust,      permanent attachment for high-load structural applications where maximum      strength and direct weld bonding are required.

Each solution carries distinct advantages depending on design specifications, production volumes, and long-term durability needs.

Why Embedded Fasteners Are Essential in Sheet Metal

✅ Create strong, reliable threaded connections in thin materials
✅ Simplify high-speed assembly and production
✅ Reduce part count and eliminate secondary machining
✅ Support blind-side assembly where access is limited
✅ Improve overall product appearance and safety
✅ Enable field serviceability for long-term maintenance

The 3 Core Fastener Options in Sheet Metal Fabrication

1️⃣ PEMs — Self-Clinching Fasteners

How PEMs Work:
PEMs are press-fit into pre-punched holes using controlled insertion force. As the fastener is pressed into the sheet metal, the surrounding material flows into an undercut groove in the PEM, permanently locking it in place.

Why Use PEMs:

• Ideal for thin sheet metal (≥0.5mm)

• Create permanent, high-strength threads

• Flush or near-flush installation for clean appearance

• Fully automated insertion possible for high-volume production

• Reliable and repeatable installation

Common PEM Applications:

• Medical device enclosures and surgical equipment

• Semiconductor tool access panels

• Photonics alignment frames

• Aerospace interior panels and lightweight structures

• Robotic automation control housings

PEM Design Considerations:

2️⃣ Rivet Nuts — Blind Threaded Inserts

How Rivet Nuts Work:
Rivet nuts are installed into pre-drilled holes from one side of the sheet. A mandrel pulls the rivet nut body, deforming it behind the sheet metal to securely anchor the fastener, even in blind locations.

Why Use Rivet Nuts:

• Allow blind-side installation where access is limited

• Adaptable to various material thicknesses

• Cost-effective for small-to-medium volume production

• Suitable for field repairs or retrofit installations

• Require minimal insertion equipment

Common Rivet Nut Applications:

• Industrial automation control boxes

• Robotic system frames

• Telecommunications cabinets

• Medical device carts and stands

• Field-serviceable panels and access doors

Rivet Nut Design Considerations:

3️⃣ Welding Studs — Projection Weld Studs

How Weld Studs Work:
Weld studs are permanently fused to the sheet metal using resistance welding or capacitor discharge welding. The stud becomes an integral part of the metal structure.

Why Use Weld Studs:

• Provide superior tensile and shear strength

• Permanent structural attachment

• Ideal for load-bearing components

• Allow fast one-side installation

• Zero fastener spin-out risk

Common Weld Stud Applications:

• Aerospace structural panels

• Semiconductor tool frames

• Heavy-duty automation bases

• Robotic machine frames

• Transport systems and enclosures

Weld Stud Design Considerations:

Quick Selection Summary