Pre-Applied Threadlocker Explained: Types, Locking/Sealing Principles and a Comparison with Mechanical Anti-Loosening
Executive Summary
A pre-applied threadlocker is a fastener that has anti-loosening material pre-coated onto the threads at the factory and cured into a dry film. During assembly it either relies on the elastic clamping of a nylon insert, or on tightening that shears open microcapsules to release adhesive that polymerizes in place—delivering "built-in anti-loosening, lock-on-assembly". Based on real technical data sheets from TufLok, 3M 2353, Precote 80/85, ND 593 and NMITEK, this article explains the two technical routes, key performance parameters, and the trade-off against mechanical anti-loosening such as spring washers and lock nuts.
Table of Contents
- What Pre-Applied Adhesive Is: "Built-In Anti-Loosening" from the Factory
- Two Technical Routes: Nylon-Insert vs Microcapsule Chemical Adhesive
- Real Performance Parameters: Breakaway Torque, Friction Coefficient and Temperature
- Pre-Applied Adhesive vs Mechanical Anti-Loosening: How to Choose
- Application, Storage and Selection Recommendations
What Pre-Applied Adhesive Is: "Built-In Anti-Loosening" from the Factory
Bolts self-loosen under vibration and alternating load. The traditional approach is to add spring washers, lock washers or cotter pins during assembly, or use nylon lock nuts—these are all "added-on anti-loosening parts" that are easy to miss, lose or carry as inventory. The pre-applied approach is to "build" the anti-loosening function directly onto the bolt: at the factory the locking material is coated onto the external or internal thread and dried into a dry, non-tacky film. When it reaches the assembly line, the worker or robot picks it up and drives it directly, with no additional dispensing, no added washer, and no risk of "forgetting the anti-loosening part".
YF Zhichengjia can supply this type of pre-applied functional coating within its surface-treatment system. Its core value is threefold: consistency (every bolt has the same anti-loosening performance, suiting large-scale automated assembly), no loss (anti-loosening is part of the bolt body), and predictable torque (friction coefficient controlled, preload stable).
Two Technical Routes: Nylon-Insert vs Microcapsule Chemical Adhesive
Pre-applied threadlocking essentially splits into two technical routes with completely different principles:
Route one: nylon (plastic) insert type. Representatives are Germany's Kerb-Konus TufLok® (blue spots) and Nytemp® (orange). It pre-coats patches of highly elastic nylon/polyamide onto the thread; when screwed into the mating thread, the nylon is squeezed and deformed, clinging to the flanks, producing reversible locking torque through elastic clamping; at the same time the nylon fills the axial clearance between threads, achieving anti-loosening plus fluid/gas sealing. It does not cure or dry out; tested per factory standards 900.1/945 and DIN 267 part 28 (external thread) and DIN EN ISO 2320 (internal thread), it is made from M0.8 up to M68, with temperature resistance of -56°C to +120°C (Nytemp up to 200°C), and can be repeatedly disassembled and reused.
Route two: microcapsule chemical-adhesive type. Representatives are 3M™ 2353, omniCHEMNIK Precote 80/85, ND Industries Microspheres 593/Eco-Loc 593, and domestic NMITEK pre-applied adhesives. It seals multi-component active adhesive (acrylate or epoxy) into polymer microcapsules barely visible to the eye, evenly dispersed in the dry coating. During assembly tightening, the pressure and shear between threads burst the microcapsules, releasing adhesive that triggers polymerization and curing; after a few hours a hard glue layer forms in the thread gap, permanently locking and sealing the thread.
| Comparison Item | Nylon-Insert Type (TufLok family) | Microcapsule Chemical Adhesive (3M/Precote/ND family) |
|---|---|---|
| Locking principle | Nylon elastic clamping; reversible | Burst microcapsules → polymerization cure; chemical lock |
| Cures to a solid? | No; always an elastomer | Yes; hard after curing |
| Disassembly | Repeated disassembly and reuse | Removable but needs tools; limited reuse |
| Sealing | Patch sealing; full-ring coating can be gastight | Cured glue fills thread gap; good sealing |
| Typical temperature | -56 to +120°C (Nytemp to 200°C) | -54 to +150°C (Precote up to 170/200°C) |
| Test standard | DIN 267-28 / ISO 2320 | DIN 267-27 / GMW 14657 |
Real Performance Parameters: Breakaway Torque, Friction Coefficient and Temperature
Pre-applied adhesive selection cannot just look at "can it prevent loosening"; you must look at quantifiable torque and friction parameters. Below is a summary of real technical data sheets for several mainstream products (all based on M10 specimens and supplier TDS measurements; actual values vary with surface treatment and size):
| Product | Chemistry | Thread Friction μ | Breakaway / Prevailing Torque | Temperature Range |
|---|---|---|---|---|
| TufLok (blue) | Nylon insert | Graded by spec | Screw-in max / screw-out min graded per DIN 267-28 | -56 to +120°C |
| 3M 2353 (blue) | Microcapsule epoxy | k controlled | Removal BLT ~55.8 N·m; breakaway BAT ~19 N·m | ≤116°C |
| Precote 80 (red) | Microcapsule acrylate | >0.25 | No-preload strength BAT >20 N·m; screw-out POT <55 N·m | -60 to +170°C (GMW to 200°C) |
| Precote 85 (teal) | Microcapsule acrylate (controlled friction) | 0.10–0.15 | BAT >20 N·m; PIT <3 N·m | -60 to +170°C (GMW to 200°C) |
| ND Microspheres 593S | Microcapsule epoxy | k: zinc-organic 0.14 / zinc-plated 0.19 | Breakaway BAT ~30 N·m | -54 to +150°C |
| NMITEK 130DMC | Microcapsule acrylate | 0.10–0.16 | Breakaway torque ≥10 N·m | 150°C |
As for cure time, microcapsule chemical adhesives usually reach final strength at room temperature 24 hours after assembly; Precote 80/85 exceed the DIN 267-27 minimum at room temperature 6 hours (fast-cure 80-3/85-3 need only 30 minutes); ND 593 fully cures in about 72 hours. Coated bolts have a shelf life of 1–4 years under controlled dry conditions.
Pre-Applied Adhesive vs Mechanical Anti-Loosening: How to Choose
Pre-applied adhesive and mechanical anti-loosening (spring washers, serrated lock washers, nylon lock nuts, cotter pins) are not mutual substitutes; each has its own use:
- Spring washer / lock washer: light load, non-critical, low cost; but its anti-loosening ability is limited in vibration tests, and it bruises the connected part's surface.
- Nylon lock nut: reversible and reusable, suited to frequently disassembled locations; but it adds nut cost and inventory, and is unfriendly to thin sheets and soft materials.
- Pre-applied nylon-insert type: combines reversibility and sealing; suited to adjustment screws and miniature parts that need repeated disassembly yet anti-loosening (as small as M0.8).
- Pre-applied microcapsule chemical adhesive: best consistency, simultaneously locks and seals; suited to high-volume automated assembly and safety-related parts (engine compartment, safety components), but it is "basically locked after assembly" and not suited to frequently adjusted locations.
Application, Storage and Selection Recommendations
- Frequent disassembly and adjustment: choose the nylon-insert type (TufLok family); reversible and reusable.
- High-volume automated assembly, requiring consistent torque + sealing: choose microcapsule chemical adhesive (Precote/3M/ND/NMITEK family).
- Low and stable friction coefficient required: choose the controlled-friction type (e.g. Precote 85, μ 0.10–0.15).
- Temperature >150°C: choose Precote 80/85 (up to 200°C per GMW 14657) or the Nytemp nylon type.
- Miniature parts (<M3): choose a type supporting coating from M0.8 (e.g. 3M 2353, NMITEK 2353 series).
- Storage: store pre-applied parts moisture-proof and temperature-controlled (generally -10 to 35°C); dampness causes whitening and hurts performance; retest expired parts before use.
The essence of pre-applied adhesive is moving "anti-loosening" from a manual action at the assembly station forward into a body function already cured at the bolt factory. For reversibility use a nylon insert; for one-time high-strength locking plus sealing use a microcapsule chemical adhesive—pick the right route, and vibrational loosening no longer depends on the worker remembering to add that washer.
Conclusion: Remember Pre-Applied Adhesive Selection in One Picture
Pre-applied threadlocker splits into two routes: the nylon-insert type (TufLok/Nytemp) relies on elastic clamping, is reversible and reusable, rated per DIN 267-28/ISO 2320; the microcapsule chemical adhesive (3M 2353, Precote 80/85, ND 593, NMITEK) bursts capsules during tightening and polymerizes in place, completing locking plus sealing in one step, rated per DIN 267-27/GMW 14657. When selecting, first see whether reversible disassembly is needed, then check whether friction coefficient, breakaway torque and temperature match the service condition, and finally land on storage and curing requirements.
YF Zhichengjia, founded in Shenzhen in 2005, is a fastener manufacturer and can supply selection, coating and torque testing for pre-applied threadlockers / anti-loosening coatings. For more material, see the technical documentation library, or contact our technical engineers for an anti-loosening solution evaluation.
