Black Metal Flat Washers

Black metal flat washers are made of high-quality medium-carbon structural steel through precision stamping and heat treatment processes. Their surface hardness has been stabilized in the range of 200 to 230 HV by multi-point testing using a Vickers hardness tester, ensuring that the contact surface is not prone to plastic depression when subjected to high pre-tightening force. In a compression test simulating standard bolt connection conditions, when the pretightening force was loaded to 120,000 N, the depth of the residual indentation between the washer and the lower bearing surface of the fastener head was only 0.025 mm. This data shows that the washer has excellent anti-collapse ability and can maintain the stability of the pretightening force of the connection pair for a long time, effectively reducing the risk of torque attenuation caused by excessive deformation of the washer. At the same time, the inner and outer diameter and thickness dimensions of the product are manufactured strictly in accordance with ISO 7089 tolerance levels, and the thickness deviation is controlled within plus or minus 0.08 mm to ensure that the pressure-bearing area of ​​each gasket in the same batch is highly consistent, avoid local overload, and provide a reliable load dispersion basis for bolted connections of large steel structures or heavy equipment.

The surface of the gasket is treated with high temperature blackening and impregnated with environmentally friendly sealed anti-rust oil. In the continuous neutral salt spray accelerated test according to GB/T 10125, no obvious red rust spots appeared on the main surface of the gasket after 120 hours of testing. It can meet the short-term anti-rust requirements in general indoor storage and dry industrial environments. In terms of friction characteristics, under standard mineral lubricating oil lubrication conditions, the test value of the dynamic friction coefficient of the contact surface between the gasket and the matching steel bolt head is stable at around 0.12, which provides a reliable basis for process parameters for torque method fastening operations and ensures that the conversion relationship between assembly torque and pre-tightening force has good reproducibility. The edges are chamfered and deburred to effectively prevent scratches on the surface of the connector during installation and facilitate automated feeding and assembly. With its balanced mechanical properties and surface protection capabilities, this black metal flat washer is widely used in automotive chassis, engineering machinery, building formwork, and power fittings where both load-bearing and cost requirements are required.

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