You are here: Through-hole and Blind-hole Rivet Nut: Operating Points and Pre-drilled Hole Machining Requirements - CHANRUI
Through-hole and blind-hole (closed) are the two most common rivet nut end structures, but they carry different processing requirements and operating details. Many on-site issues such as uneven bulge, a screw that fails to withdraw, and leakage come from mixing the two or failing to machine the pre-drilled holes as required. This article consolidates the operating points and processing requirements into a version that can train workers directly.
I. How through-hole and blind-hole types differ
| Comparison | Through-hole (open) type | Blind-hole (closed) type |
|---|---|---|
| Configuration | The shank stays open, so the screw can pass out through the tail end during pull riveting | The tail end is closed into a dome, and the screw cannot pass through |
| Pre-drilled holes | Machine round or hexagonal holes according to the specification table | Also per the specification table, yet more sensitive to hole-diameter tolerance |
| Sealing | Offers no leakage prevention | The closed end blocks liquid and moisture, so it suits liquid/gas-tight positions |
| Typical applications | General connections, for example cabinets, brackets and internal appliance parts | Water tanks, oil tanks, piping, outdoor enclosures and chassis parts |
| Inspection key point | Bulge, thread go/no-go check, plate surface | Besides the above, inspect the closed end for puncture or leakage |
II. Pre-drilled holes and plate-thickness requirements
Rivet nut outer diameter D, mounting hole diameter d and plate thickness G correspond one-to-one, and every specification catalog lists the recommended hole diameter and plate-thickness range. Note during machining: keep the hole diameter at the recommended value - too large makes the nut loosen and follow rotation, too small prevents insertion or makes the bulge abnormal; the plate thickness a given nut fits has upper and lower limits, and the total stacked thickness must stay within that range; the hexagonal hole's six-sided dimensions and orientation must be accurate, for which a dedicated punch is advised; the hole perimeter must be free of burrs, obvious edge collapse and weld spatter, or seating will be incomplete. The equipment only delivers stable pull riveting, and unqualified holes cannot be made up for by the equipment.
III. Standard operating steps
1) Fit the screw and rivet head matching the nut specification, and confirm the gun is switched to the corresponding program; 2) the nut automatically screws onto the screw (on manual models, screw it into place by hand); 3) keep the gun head perpendicular to the plate surface, insert the nut into the pre-drilled hole and seat it tightly - no angled insertion and no gap; 4) start pull riveting, and the equipment automatically finishes pulling/bulging, setting and screw reversal/withdrawal; 5) visually inspect the bulge and plate surface, and check the thread with the matching screw or go/no-go gauge; 6) for blind-hole parts, additionally confirm the backside closed end is intact. Throughout, "perpendicular, seated firmly, no gun wobble" are the three essential action requirements.
IV. First-article check and in-process sampling
After every shift start, nut batch change, specification change or worker change, the first piece must go through first-article confirmation: rivet 3-5 consecutively, check whether the bulge is symmetric, whether the plate surface is depressed, and whether the thread go/no-go passes, and perform leakage or closed-end inspection for blind-hole parts; in mass production, sample at fixed intervals and run the necessary pull-out/torque tests. Stop immediately on any single-piece anomaly and troubleshoot per the fault table; common faults are inRivet Nut Gun Common Faults and Installation Problem Troubleshooting。
V. Common operating defects and prevention
| Defect | Cause | Prevention |
|---|---|---|
| Bulge skewed, nut misaligned | Gun angled, hole too large, not seated | Seat the gun perpendicularly, control the hole diameter, use a positioning fixture |
| Plate surface crush or depression | Rivet head mismatch, pulling force too high, countersink too deep | Switch to a matched rivet head, adjust stroke/pulling force, verify the countersink |
| Blind-hole end puncture or leakage | Pulling force too high, plate thickness below the lower limit, wrong specification | Select by plate thickness, perform leakage inspection on the first article |
| Screw withdrawal damages the threads | Worn screw, withdrawal before setting | Replace the screw, and confirm the full pull-riveting stroke |
Operating Points FAQ
Through/Blind-hole FAQ
For the same thread specification the same screw can usually be used, yet confirm the rivet head and program by type; the blind-hole stroke setting differs, so run a first article on changeover.
It must seat tightly against the plate surface so the closed end forms correctly and sealing is ensured; a gap causes an incomplete bulge and a leakage risk.
Observe three points: whether the gun stays perpendicular to the plate, whether the rivet head is seated, and whether the gun wobbles during pull riveting; the manufacturer teaches these one by one during on-site training.
Trial-rivet with real plate-thickness coupons, run thread go/no-go, appearance and pull-out/torque tests, add leakage verification for blind-hole parts, and mass-produce only after passing.
Unsure about the through/blind-hole process? On-site trial riveting
The manufacturer can bring machines to verify forming and sealing on-site with customer workpieces; consultation hotline +86 13268883882.
VI. Positioning fixtures and error-proofing steps
In mass production, hole-position consistency is ensured by fixtures: for regular parts such as door panels and mounting plates, it is advisable to make positioning fixtures or profile tooling, so that once the workpiece is placed the holes naturally align with the gun head and the worker only seats the gun and starts, preventing angled riveting and lowering labor intensity; at stations mixing several nut specifications, use color or marking distinctions on screws, rivet heads and trays, and confirm item by item against a checklist on changeover to prevent through/blind hole mixing and M5/M6 misassembly. For stacked plate connections, confirm the two layers' holes are coaxial and the mating faces are seated, since gaps let the bulge form in the seam and cause looseness; for blind-hole parts it is advisable to add backside support to the fixture to avoid plate deformation when the closed end forms.
The closed and open ends are distinguishable to the naked eye; store them in specification-specific bins with markings, use independent channels for different specifications on auto-feed equipment, and have the team leader double-check at first article and changeover to error-proof by process.
Recommended reading:Pull Rivet Nut Types and Selection Comparison · Maintenance Items and Wear Parts · Automatic Rivet Nut Gun
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