Oct 20, 2026Quality Control
Locking Methods: Split Lock Washers, Star Washers, Nylon-Insert Nuts or Patch?
Compare split lock washers, star washers, nylon-insert lock nuts and patch screws, and choose the right locking method for vibration and assembly needs.
Fastener loosening is a common problem in equipment, vehicles, electrical products and many industrial assemblies. Vibration, repeated movement and poor tightening control can all make a screw or nut lose preload over time.
There is no single locking method that works best for every application. Split lock washers, star washers, nylon-insert nuts and patch screws all have their own advantages and limits. The right choice depends on vibration level, temperature, surface material, assembly method and whether the part needs to be removed later.
Split Lock Washers
Split lock washers, also called helical spring washers, are one of the most traditional locking methods. They are low cost, easy to source and widely used in general assemblies.
When compressed, the washer creates spring force and friction between the nut or screw head and the contact surface. In light-duty applications, this may be enough.
However, split lock washers should not be treated as a strong anti-vibration solution. Under serious vibration, they may not perform as well as many people expect. They can also mark soft or finished surfaces.
Use split lock washers for low-cost, general-purpose assemblies with light vibration.
Star Washers
Star washers have teeth that bite into the contact surface. They can be internal tooth, external tooth or internal-external tooth types.
They are often used where extra grip is needed on the surface. They can also help with electrical grounding because the teeth can cut through light oxidation or coating and improve contact.
The drawback is that the teeth may damage painted, plated or soft surfaces. If the teeth become flattened, the locking effect can also be reduced.
Use star washers when surface bite or electrical contact is needed, and when surface marking is acceptable.
Nylon-Insert Lock Nuts
Nylon-insert lock nuts, also called nyloc nuts, use a nylon ring to create friction against the bolt thread. This helps resist loosening under vibration.
They are a common and practical choice for many mechanical assemblies. Compared with simple washers, nylon-insert nuts usually provide more consistent locking performance.
However, they are not suitable for all conditions. High temperature can reduce the locking function of the nylon insert. They also should not be reused too many times, because the locking force can become weaker after repeated assembly.
Use nylon-insert lock nuts when reliable vibration resistance is needed and the temperature is within the suitable range.
Patch Screws
Patch screws or patch nuts have a pre-applied locking material on the thread. The patch creates extra friction or locking action during assembly.
This method is useful when the buyer wants a cleaner assembly without adding a separate washer or lock nut. It can also reduce missing-part problems on the production line because the locking function is already on the screw or nut.
Patch fasteners are often used in equipment, electronics, automotive parts and other assemblies where stable locking is required.
The limitation is that patch type, patch position, torque requirement and reusability should be confirmed before production. Some patch solutions are better for one-time assembly, while others allow limited reuse.
Use patch screws when the locking function needs to be built into the fastener itself.
Simple Selection Logic
If the project needs a low-cost locking method for light-duty use, split lock washers may be enough.
If the part needs surface bite or electrical grounding, star washers can be considered.
If the assembly has vibration and uses a nut-and-bolt connection, nylon-insert lock nuts are often a practical option.
If the buyer wants a pre-applied locking function without separate parts, patch screws or patch nuts may be suitable.
Before quotation, buyers should confirm the vibration level, working temperature, mating material, surface finish, installation torque, reusability requirement and whether surface marking is acceptable.
A locking fastener should not be selected only by habit. The best solution is the one that matches the real assembly condition.
Hextro supports split lock washers, star washers, nylon-insert lock nuts, patch screws, SEMS screws and other locking fastener solutions according to drawings, samples and application requirements.
