A4-035 Lock Nut

About A4-035 Lock Nut

The A4-035 Lock Nut (most commonly classified as a Thin Hex Nut, Jam Nut, or Half Nut) is a low-profile, marine-grade internal thread metric fastener. The alpha-numeric designation "A4-035" explicitly defines its high corrosion resistance and light mechanical property threshold under international standards like ISO 3506-2:

         "A4" indicates it is forged from Grade 316 austenitic stainless steel, fortified with 2% to 3% Molybdenum.

         "035" signifies a lower minimum tensile strength profile of 350 MPa (or 350 N/mm), which is standard for thin-type or non-load-bearing fasteners that do not handle full structural clamping loads.

Because it is approximately half the thickness of a standard hex nut, it is primarily used as a "jam nut" to lock a regular nut in place, or as a standalone fastener in compact housings where space and clearance are extremely limited.

Key Features & Design

         Low-Profile Thickness: Engineered with a highly compact vertical footprint, making it ideal for tight-clearance assemblies and lightweight electronic or fluid-line components.

         "Jamming" Locking Action: When threaded onto a bolt directly against a standard full-height nut (such as an ISO 4032 or DIN 934 nut) and tightened against each other, the two nuts "jam" together. This forces the thread faces into opposing tension, preventing the assembly from backing off under dynamic vibrations.

         Superior Chemical and Saline Defences: The molybdenum-enriched A4 alloy provides exceptional resistance against pitting, crevice corrosion, and chloride-induced stress cracking caused by seawater and harsh acids.

         Non-Magnetic Properties: Retains an almost entirely non-magnetic structure, making it ideal for medical imaging equipment, sensitive marine instrumentation, and telecommunications gear.

Manufacturing & Dimensional Standards

A4-035 thin lock nuts are precision-machined to comply with widespread global low-profile specifications:

         ISO 4035: The primary international standard for regular thin hex nuts (Product Grades A and B).

         DIN 439 / DIN 439B: The classic, widely referenced German industrial standard for hexagonal thin nuts/jam nuts.

         Thread Fitting: Formed to standard metric coarse or metric fine thread pitches with a precision 6H internal thread tolerance class.

Mechanical Property Profile

         Alloy Type: Austenitic Stainless Steel (Type 316 / Marine Grade / Acid-Proof).

         Minimum Tensile Strength: 350 MPa.

         Minimum Yield Strength: Approximately 240 MPa.

         Thermal Range: Safely retains structural form and surface characteristics across extreme thermal shifts, maintaining integrity from sub-zero levels up to 400C.

Target Applications & Industries

         Marine Electronics & Subsea Instruments: Securing toggle switches, sensors, control panel interfaces, and small underwater casing plates.

         Chemical & Petrochemical Processing: Used as a locking component on light-duty valve linkages, fluid gauges, and instrument tubing arrays.

         Medical & Pharmaceutical Hardware: Fastening diagnostic equipment, laboratory mixers, and cleanroom cabinetry where sterilization chemicals would corrode lower-grade steels.

         Water Desalination Plants: Assembling lightweight sensor mounts, brackets, and compact flow meters exposed to continuous salt spray and brine.