Nylon locking nuts, also termed as stop nuts, nyloc, elastic stop, nylon-insert lock or polymer-insert lock nuts, are threaded hex nuts with a nylon insert, or collar, which is smaller than the thread diameter. As the nylon insert lock nut is tightened, the collar deforms over the mating screw/bolt threads, increasing friction on them, thus resisting vibration and loosening and maintaining reliable locking performance.These nuts are a preferred choice for equipment exposed to movement or vibration. Different colors are often used to identify them as either imperial (inch) or metric threaded. Although these nuts are considered as reusable, their strength is reduced each time and therefore their reuse is not recommended in applications where safety is paramount. Typically, nyloc nuts can operate as intended in temperatures up to 248˚F (120˚C), but certain nuts exceed this limit.

Nylon Locking Nuts are offered by various manufacturers in different styles (low or high-profile, flange or others), sizes (body heights), coarse or fine thread versions, materials & finishes (e.g. steel with zinc, yellow zinc, or zinc flake finishes, or corrosion resistant stainless steel.

Nylocs listed in our Web Platform for Supplies are offered as OEM parts under the brands of the respective manufacturers or as parts of our own labelled (AVIATIONEU NEW ERA) product lines, sourced from various quality manufacturers/ distributors and intended as cost effective alternatives to the respective OEM parts. 

Howmet® Aerospace Simmonds® Self-Locking Nuts

Howmet® Aerospace Inc. (Howmet® Fastening Systems, HFS), formerly Arconic Inc., develops & manufactures high performance, engineered products & solutions for the aerospace, industrial gas turbine, commercial transportation and oil and gas markets. HFS product range under different brands offers the greatest breadth and depth of fastening solutions available including self-locking nuts, quick-release fasteners, draw latches, threaded inserts, lock-bolts, and structural blind fasteners. Alcoa Fastening Systems (Alcoa), a business unit of Howmet® Aerospace is one of the largest manufacturers of aerospace hardware in the world. Simmonds®, a Howmet® Aerospace business unit, specialises on self-locking & special nuts. Their self locking nuts come in different types (series) offered in different materials and sizes, and can be reused (fully tightened and loosened) at least 15 times without affecting the nut's performance. Born for the world of aviation, Simmonds® self-locking nuts are lightweight and extremely durable, exhibit a very strong locking performance, resistance to heat and corrosion & can be used in a wide temperature range in demanding aerospace, rally & other applications.

Simmonds® self locking nuts come in different types (series) offered in different materials and sizes, and can be reused at least 15 times without affecting the nut's performance. They are lightweight and extremely durable, exhibit a very strong locking performance & can be used in a wide temperature range. Their product portfolio is briefly presented below.

Nylstop® - Original Nylon Locking Nuts
The Simmonds® Nylstop® (*) Type P (Standard Version) and Type T (Low Profile Version) nylon locking nuts have been designed to stop nut and bolt disengagement during use. The internal nylon ring deforms around the threads as the nut is twisted on to the bolt, ensuring a tight, vibration resistant grip on the bolt.Their PH Series Aerospace quality hexagonal self-locking nuts are small, thin walled, lightweight and extremely strong. Made from CRES A286 stainless steel and silver plated these nutls are particularly useful when space and weight are at a premium. Used typically in engine applications they are MJ threaded and offered in Meric diameters M3-M12 to meet different applications requirements. Simmonds® MHT Series are conical shaped self locking nuts, where the diameter of the upper part of the nut is slightly reduced. Six vertical slots will open gradually whilst the nut is screwed onto the bolt. The elasticity provided by the particular shape of the nut will ensure the required locking torque.
(*) Nylstop® is a trademark of Howmet Fixations Simmonds SAS and /or its subsidiaries.

Simmonds® Nylstop® Type P/T Product Features:
Available in 2 different types (styles), P-Normal Height , T-Low Height
Vibration resistant - The deformation of the nylon ring holds the fastener in place even under extreme vibration
Corrosion resistance - The standard product is Zinc Nickel plated achieving a minimum 720 hours on salt spray test
Re-usability - Can be fastened and unfastened a minimum of 15 times without compromising minimum required performance (ISO 2320)
Consistency - The Nylstop nuts permits a complete automation of installation because of constant quality and very low scatter of the locking torque. This allows installation without concerns of defective or non-conforming nuts and reduces the cost of monitoring and tight inspection.
Chemical resistance - The nylon 6.6 polyamide used is completely insensitive to a myriad of acids, solvents and oil based liquids
Temperature resistance - Operating temperature range between -40°C and 140°C (peak condition)
Popular Applications: Any industrial application
Diameters: M2.5 - M52
Materials: Steel CL8 & CL10, Stainless Steel A2 & A4
Standard Coating: Zinc Nickel

Simmonds® PH Product Features:
Lightweight, self-locking and extremely strong
Thin walled nut, takes less space
Very high resistance to loosening
Very high mechanical resistance 1100 MPA
Very high locking torque (according to aerospace standards)
Consistency of performance. Almost no locking torque scatter
Flanged. Ideal for thin sheet material
Temperature & Corrosion Resistance. Operating temperature range between -40°C and 480°C 
Re-usability. They can be fastened and unfastened a minimum of 15 times without compromising minimum required performance
Manufactured from CRES A286 stainless steel  and silver plated
Diameters: M3-M12
MJ Threads. MJ thread is a special form of thread that is used in the aerospace market for applications in aircraft, rockets and space stations that require high stress or high temperture. The MJ thread standard is specified in ISO 5855. The minor diameter is larger and the pitch diameter tolerance is more strict than general Metric threads.  The MJ thread may be considered as a modified metric version of the UNJ imperial threads as it contains a controlled root radius on external threads but also a truncated internal diameter to accept a bolt that has this external root radius.

Simmonds® MHT Product Features:
Temperature resistance - Operating temperature range up to 120°C. Reacts swiftly to sudden temperature change and maintains locking torque
High Fatigue resistance - Nut design permits a less aggressive contact during and after installation reducing stress levels inside the bolt and nut
Vibration resistant - The six beams hold the fastener in place even under extreme vibration
Re-usability - can be fastened and unfastened a minimum of 15 times without compromising minimum required performance (ISO 2320)
Consistency - Extremely low scatter of the locking torque. Locking torque more predictable than any other prevailing torque nut
Corrosion resistance - The standard product is Zinc Nickel plated achieving a minimum 720 hours on salt spray test
Popular Applications: Pumps, engines, turbo chargers, braking systems
Diameters: M5 - M20
Materials: Steel Class 8
Standard Coating: Zinc Nickel
For additional information on nylon locking nuts please refer to the respective product presentations at our Web Platform for Supplies (shop.aviationeu.supplies), the separate presentations or media files available in our Resource Repository, or contact us.