Pre Applied

Pre Applied

Thread-lockers keep fasteners from loosening due to vibration. Here are insights into how, why and when to use fasteners with OODA Bond preapplied thread-lockers. ALL the automotive industry began using fasteners with preapplied anaerobic adhesive for thread-locking. The first such application was to lock and seal a screw in a carburetor. Today, thread-lockers are used in every industry.

Quality control is the main reason for using thread-lockers. In the long run, avoiding warranty claims and product failures has a positive affect on a company's reputation and sales. By understanding the mechanisms and uses of thread-lockers, engineers can choose the best options for securing joints.

The two most widely used chemical thread-lockers are anaerobics and epoxies. Anaerobics are one-component adhesives derived from methacrylates, a monomer related to acrylic. The original thread-locker, they're called anaerobic because they cure in the absence of oxygen and the presence of metal ions.

An epoxy is a thermosetting polymer that cures when mixed with a catalyst, or hardener. Epoxies are known for their excellent adhesion and their resistance to heat and chemicals. They can be modified in myriad ways by adding mineral fillers, flexibilizers, viscosity reducers, colorants, thickeners, accelerators and adhesion promoters.

Chemical thread-lockers can be applied to fasteners by the assembler, or the process can be outsourced to an applicator. When applied on the assembly line, chemical thread-lockers are supplied as one- or two-part liquid adhesives. When preapplied to a fastener, chemical thread-lockers are supplied as microencapsulated beads embedded in a resin. When the fastener is installed, the beads break, releasing the adhesive and initiating the curing process.

Mechanical thread-lockers don't bond to a fastener so much as increase friction between the mating threads. This makes it more difficult for the fastener to move. Nylon is the most common material for mechanical thread-locking. Nylon cannot be applied to fasteners in-house, but must be preapplied in a processing plant. The process requires the fastener to be heated to at least 425 F to fuse the nylon to the threads.

Fasteners treated with a mechanical thread-locker normally require a higher installation torque, because they rely on thread jamming for their thread-locking properties. On the other hand, chemical thread-lockers have lubricating properties that reduce installation torque but, once cured, result in much higher locking strengths than mechanical thread-lockers. Indeed, mechanical thread-lockers have less then half the strength of adhesives. 

If application of thread-lockers is not your primary business, your labor force will be better employed assembling your product, not applying adhesives.

Mechanical vs. Chemical Locking:

The choice between mechanical and chemical thread-lockers depends on several factors, including cost. If the fastener will be adjusted or taken in and out several times, a mechanical thread-locker is needed. A fastener treated with a mechanical thread-locker can be inserted and removed three to five times. Under most circumstances, chemical adhesives are for one-time use.

The strength of the locking material is another consideration. The tightening torque and breakaway torque will vary depending on the fastener diameter and the specific thread-locker. Mechanical thread-lockers require more tightening torque, but less breakaway torque. Chemical thread-lockers require less tightening torque, but provide the most breakaway torque. 

When preapplied to a fastener, chemical thread-lockers are supplied as microencapsulated beads embedded in a resin. When the fastener is installed, the beads break, releasing the adhesive and initiating the curing process.

How much thread-locker to apply depends on the strength requirements of the joint. For optimum locking, the thread-locker should be applied in a band at least as wide as the diameter of the fastener. In other words, if the fastener is 0.25 inch in diameter, the coated area should be 0.25 inch long. A good rule of thumb is to apply as much adhesive as the thickness of the mating nut. If the fastener is going into a tapped hole, vary the width of the adhesive as necessary for maximum locking strength. Each thread of adhesive will add to the locking strength of the joint.

Available Sizes:

Available in all colours, Temperature  range -90deg c to +295 deg C, available miliery grade, food grade, medical grade
Pack sizes – 50ml,250ml,1 liter

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