Introduction to Models and Applications of Non-Removable Threadlockers
I. Basic Principles of Non-Removable Thread-Locking Adhesives
Non-removable thread-locking adhesives are essentially functional adhesives, whose core mechanism of action revolves around "filling gaps" and "enhancing friction". During the processing and assembly of threaded fasteners, tiny gaps are inevitably present between thread teeth. These gaps lead to uneven force distribution and easily cause loosening under vibration, impact, or temperature changes. Non-removable thread-locking adhesives can fully fill these gaps; after curing, they form a tough adhesive layer, transforming the contact between threads from "point contact" to "surface contact", which significantly improves friction and sealing performance.
Meanwhile, different models of thread-locking adhesives achieve characteristic adaptation through differentiated chemical compositions: Anaerobic adhesives trigger a curing reaction when isolated from air and in contact with metal ions, making them suitable for metal threaded connections; Epoxy adhesives, relying on a two-component cross-linking reaction, combine high strength and chemical corrosion resistance, adapting to multi-material threaded scenarios. This principle-based characteristic allows non-removable thread-locking adhesives to achieve precise matching in terms of strength, temperature resistance, corrosion resistance, and other dimensions according to specific application requirements.
II. Models and Application Scenarios of Non-Removable Thread-Locking Adhesives
There is a wide range of non-removable thread-locking adhesive models on the market, with significant differences in strength, applicable thread size, and working condition adaptability. The following are several common and practical models:
LOCTITE 270: The "High-Strength Lock" for Heavy-Duty Equipment
As a representative of high-strength non-removable thread-locking adhesives, LOCTITE 270 is suitable for large threaded fasteners with diameters ranging from 3/8 inch to 1 inch. After curing, it exhibits extremely high shear strength and excellent vibration resistance, heat resistance, and corrosion resistance—it can work stably in environments ranging from -54°C to 150°C and tolerate short-term exposure to temperatures up to 200°C. In high-strength scenarios such as spindle bolts and base fixing bolts of heavy-duty equipment (e.g., mining machinery, large machine tools), as well as connecting bolts between automobile engine blocks and frames, it can effectively resist long-term heavy loads and severe vibrations, preventing equipment displacement or leakage caused by thread loosening.
LOCTITE 263: The "Universal Guard" for Small and Medium-Sized Equipment
This medium-strength thread-locking adhesive is suitable for threaded fasteners with diameters not exceeding 3/4 inch, balancing strength and practicality. It also features vibration resistance and corrosion resistance, with a moderate curing speed, and performs outstandingly in scenarios such as automobile transmission gear bolts, motorcycle engine cylinder head bolts, and threaded connections for bicycle bottom brackets and pedals. For example, during motorcycle operation, the vehicle body vibrates frequently; the adhesive layer formed after LOCTITE 263 cures can firmly lock the threads, avoiding component loosening caused by vibration and ensuring riding safety.
PERMABOND A131: The "All-Rounder" for Industrial Scenarios
PERMABOND A131 is a high-strength non-removable thread-locking adhesive, suitable for threaded fasteners with diameters ranging from 1/4 inch to 3/4 inch. Its advantage lies in "versatility"—it not only offers vibration resistance, heat resistance (operating temperature range: -40°C to 150°C), and chemical corrosion resistance but also adapts to multiple metal materials such as steel, aluminum, and copper. In scenarios such as drive shaft bolts of heavy-duty equipment, bolts of automobile chassis suspension systems, and threaded connections of petrochemical equipment pipelines, it can maintain stable locking performance in the face of oil contamination, acid-alkali environments, and continuous vibration, preventing medium leakage and component failure.
Supplementary Models: Classic Options for Specialized Scenarios
In addition to the above models, LOCTITE 277 and ThreeBond 1344 are also widely used. LOCTITE 277 has high viscosity, making it suitable for larger-diameter threads; in the connection between rollers and frames of conveyor systems, it can resist vibration during long-term operation. ThreeBond 1344 has strong penetration, making it suitable for fixing small threads of heat sinks on PCB boards in electronic equipment, ensuring the stability of components during equipment transportation and use.
III. Precautions for Using Non-Removable Thread-Locking Adhesives
To fully utilize the performance of non-removable thread-locking adhesives, it is necessary to strictly follow usage specifications and avoid ineffective results due to improper operation:
Cleaning: Ensuring the Foundation for Adhesion
Before use, it is essential to clean the surfaces of threads and fasteners to remove oil, rust, dust, and other impurities—oil will hinder the contact between the adhesive and the metal surface, leading to incomplete curing; impurities will form "weak points" in the adhesive layer, reducing locking strength. It is recommended to wipe the surfaces with anhydrous ethanol or a dedicated metal cleaner and apply the adhesive only after the surfaces are dry.
Quantity Control: Balancing Effect and Cost
The amount of adhesive applied must be precisely controlled according to the thread size: for small threads (diameter less than 1/4 inch), the adhesive should cover 1-2 thread teeth; for large threads (diameter greater than 3/4 inch), the adhesive can be evenly applied along one full circle of thread teeth. Excessive adhesive will cause excess colloid to overflow after curing, contaminating components or affecting assembly accuracy; insufficient adhesive will fail to fill gaps, making it difficult to form an effective adhesive layer and resulting in poor anti-loosening performance.
Curing: Waiting for Optimal Results
Different models of thread-locking adhesives have different curing times: Anaerobic adhesives (e.g., LOCTITE series) typically achieve initial curing within 10-20 minutes at room temperature and reach full strength after 24 hours; Epoxy adhesives (some PERMABOND models) require 24-48 hours for curing at room temperature, and curing time can be shortened to 30 minutes-2 hours with heating (80-120°C). Sufficient curing time must be allowed before use; subjecting the adhesive to force before complete curing will cause the adhesive layer to crack and the connection to loosen.