Blind Rivets, Lockbolts, or Rivet Nuts? How to Choose the Right Fastening System

Walk any assembly line, body shop or fab floor and you will find three fastening systems doing most of the work: blind rivets, lockbolts, and rivet nuts. They look related, and the tools that set them can look similar, but they solve genuinely different problems. Picking the wrong one usually shows up later as a loose joint, a warranty claim, or a tool that is being asked to do something it was never rated for.

Here is how we help customers sort it out.

Blind rivets: one-side access, fast cycle times

A blind rivet is the right answer when you can only reach one side of the joint. The rivet is inserted, the tool pulls the mandrel, the rivet body upsets against the back side, and the mandrel snaps off. Cycle time is under a second in trained hands.

Blind rivets are ideal for sheet metal panels, enclosures, trailer skins, HVAC ducting, and light structural work. They are not the answer when the joint sees heavy vibration or high shear loads over years of service - the mandrel break point is a stress riser and the clamp force is modest.

What to look for in the tool: traction power (the pulling force in pounds) has to exceed what the largest rivet in your mix requires. A tool rated at 1,320 lb will set 3/16" steel rivets all day; step up to 3/16" stainless or a 1/4" aluminum monobolt and you want 2,000 lb or more. Our blind pull riveters are listed by traction power for exactly this reason.

Do you need vacuum?

Vacuum riveters collect the spent mandrel inside the tool instead of dropping it. On a line that is a housekeeping question; in an aircraft, a fuel tank, or an electrical enclosure it is a safety question. A loose mandrel rattling inside a finished assembly is a FOD problem nobody wants to find later.

Lockbolts: when the joint has to stay tight

A lockbolt is a two-piece permanent fastener - a pin and a collar. The tool pulls the pin to a controlled tension, then swages the collar into the pin locking grooves. There is no mandrel break point, and the clamp load is far higher and far more consistent than a blind rivet.

This is what you use on truck and trailer frames, rail cars, agricultural equipment, shipping containers, and anywhere vibration would loosen a threaded fastener. A properly set lockbolt does not back off.

The two common systems are C6L (a pull-type lockbolt) and Magna-Grip (which tolerates a wider grip range). Tools like the ZT2318HK pull both 3/16" and 1/4" lockbolts in either system at 5,000 lb traction power, and the ZT3213 steps up to 7,050 lb for 3/8" work. The nose assembly is what determines which system and diameter you are set up for, so most shops keep a small set on the bench. See our lockbolt tools.

Rivet nuts: adding threads to thin material

Rivet nuts (and their cousins, rivet studs) exist to solve a different problem entirely: you need a threaded attachment point in material too thin to tap. The tool threads onto the insert, pulls it to upset a bulge on the blind side, then spins off, leaving a usable machine thread behind.

You will see them in automotive interiors, appliance panels, battery enclosures, solar racking, and any assembly where a component has to be removable for service. That serviceability is the whole point - unlike a rivet or lockbolt, a rivet nut joint can be taken apart and put back together.

Spin/pull/spin vs. spin-spin

This is the choice that trips people up. Spin/pull/spin tools like the ZRN1606E and ZRN2508E use hydraulic pull force and give you precise, repeatable stroke control - the right choice when insert quality is critical or when you are running a wide range of sizes (#8-32 through 1/2"-13, or M4 through M12). Spin-spin tools like the ZRN500Q and ZRN280Q are faster and simpler, driving the insert purely by rotation. They are excellent for high-volume runs of a single size, and quick-change nosing means a size swap takes seconds. Browse our rivet nut insert tools.

One practical note: metric and imperial are not interchangeable. The mandrel threads have to match the insert exactly. We stock both - look for the E suffix for imperial and the M suffix for metric.

A quick decision table

• One-side access, light-to-medium load, speed matters - blind rivet
• Permanent joint, high vibration, high clamp load - lockbolt
• Needs to come apart for service, thin material - rivet nut
• Threaded stud needed instead of a threaded hole - rivet stud

Not sure? Call us.

Grip range, material stack, hole prep and load direction all factor in, and the right answer is usually obvious once someone hears the details. Our service technicians have been doing this a long time - reach us at +1 (330) 677-1330 and we will help you match the fastener and the tool.