Case Studies | CRRC, AVIC & CSCEC Fastener Projects

CherryMAX® rivet — localised replacement models CR3212/CR3213

Innovation

Localised replacement of CherryMAX® blind rivets

Aerospace fasteners · co-developed with the Shanghai Fastener Research Institute

CherryMAX® blind rivets are a standard fastening solution in high-end equipment, and the technology was long controlled by foreign suppliers. For Chinese manufacturers that meant paying 5–8 times the price of an ordinary domestic rivet, waiting 6–8 weeks for delivery, and carrying a supply chain exposed to trade restrictions.

What we engineered

Domestic blind-rivet models CR3212-6-06 and CR3213-6-06, developed jointly with the Shanghai Fastener Research Institute.
A 7050 aluminium alloy and titanium alloy combination refined through more than 200 heat-treatment trials — tensile strength raised to 620 MPa against the original maker's 580 MPa, salt-spray resistance beyond 500 hours.
A purpose-built cold-heading → spin-forming → precision-finishing line that holds the shaped rivet head to ±0.01 mm.
Over 2,000 fatigue, vibration and extreme-environment tests completed with independent third-party laboratories.

620 MPaTensile strength

±0.01 mmHead tolerance

2,000+Validation tests

+15%Fatigue life vs. imports

Result

Every measured indicator matched or exceeded the original manufacturer's standard, with fatigue life 15% longer than the imported part. Local production removed tariffs, freight and long lead times from the bill of materials, and gave domestic aerospace and rail-transit programmes a supply source that is not exposed to external trade risk.

Fire protection systems in service at a data centre project

Industry

China Construction Fifth Engineering Bureau — Ulanqab Data Centre fire protection package

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Fire doors, fire shutters and hydrant boxes · estimated contract value RMB 2 million

We won the fire-protection product package for the mechanical and electrical contract of the Ulanqab data centre in Inner Mongolia, undertaken by the Beijing branch of China Construction Fifth Engineering Bureau. The scope covered fire doors, fire shutters and hydrant boxes for machine rooms, office areas and fire escape routes — a full-scenario fire protection system for a North China data hub.

What we supplied

Grade A fire doors: 1.2 mm cold-rolled steel frames, 0.8 mm leaf panels, A1-class rock wool (≥80 kg/m³), fire resistance ≥1.5 h to GB 12955-2008, 304 stainless hinges and electromagnetic release, smoke toxicity ZA2.
Grade B fire doors: 50 mm leaf with mechanically sprayed inorganic core and electrostatic powder coating — ≥1,000 h salt spray, serviceable from −40 °C to 120 °C.
Fire shutters: double-track double-curtain steel shutters rated ≥3.0 h with smoke leakage ≤25 m³/(m²·h) for spans up to 18 m, plus inorganic cloth shutters certified to GB 14101-2005.
Hydrant boxes to GB/T 14561-2019 and fire passage doors rated Class 9 for wind pressure (GB/T 7106-2019). All doors and shutters carry CCC certification and accredited type-test reports.

Engineering around the environment

Machine rooms run continuously at 25 ±2 °C and 40–60% RH, under constant vibration from operating equipment. We specified nickel-plated 304 stainless hinges (≥0.25 µm) and hydrophobic-treated rock wool with water absorption ≤1.5%, added anti-seismic limiters to the shutter guide rails, and joined shutter slats by riveting plus spot welding. Every door is fire-tested before despatch, every shutter passes 1,000 open-close cycles, and door status is reported to the fire control centre over NB-IoT with dual-power backup switching in ≤0.1 s.

45 daysDelivery, 30% faster than average

99.6%First-pass acceptance rate

2,000 + 50Doors and shutters supplied

−28%Cost vs. imported solution

"Ningxin Huida's products performed excellently in the extreme environment of the Ulanqab Data Center. In particular, the heat insulation performance of fire doors and the reliability of fire shutters exceeded expectations. The seamless integration of its intelligent monitoring system with the data center's security platform has provided strong support for the intelligent management of the project."
Project Manager, China Construction Fifth Engineering Bureau Beijing Company

Special hook and lifting component manufactured by NXHD

Customisation

All-weather rapid-deployment hoisting system for special vehicles

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Custom lifting hardware · engineered for extreme off-road conditions

A heavy special-vehicle programme operating far from any workshop needed three things solved at once: rapid assembly and disassembly of aerial frames in the field, emergency tyre hoisting and replacement without external power, and secure tie-down of equipment at highway speed.

The three requirements

Aerial frame hoisting positioned within ±2 mm in extreme cold and sandstorm conditions.
A tyre clamping mechanism that swaps a 1.5-tonne tyre within 3 minutes with no external power supply.
A net pocket system that holds equipment steady under vibration and impact at 120 km/h.

What we built

An all-terrain aerial frame hoisting system with a patented centre-of-gravity compensation algorithm — stable hoisting on slopes up to 30°, and modular assembly in 8 minutes, a 300% efficiency gain.
A self-generating hydraulic tyre clamp operable by a single operator, sealed and validated across −45 °C to 70 °C.
An intelligent anti-sway net pocket with dynamic tension adjustment, cutting equipment sway by 90%.

3 min 20 sTyre change, from 15 min

72 hFault-free desert field operation

10 tNet pocket impact test passed

−35%Lifecycle cost

"The hoisting system performed without a single fault throughout the field trials, and the 24-hour emergency technical support behind it makes this a partner we can rely on for the long term."
Equipment Support Programme Lead

High-strength bolt being torqued on a heavy vehicle chassis

Breakthrough

CRRC — localising fasteners for CR240E mining trucks

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Rail and heavy equipment · patent No. 202422375556.0

Imported fasteners for CRRC's CR240E mining trucks carried three penalties at once: high purchase cost, a 45-day lead time, and supply-chain risk. Mining service is unforgiving on bolt locking, hose clamp sealing and casting strength — the parts had to get better, not just cheaper.

Three engineering breakthroughs

Patented dynamic bolt locking ("High-Strength Dynamic Anti-Loosening Fastening System"): thread stress distribution optimised for +40% vibration fatigue resistance, removing the loosening risk on the truck chassis.
Adaptive sealing hose clamp: an elastic structure that pushes pipeline sealing life past 8,000 hours, beyond the imported standard.
Topology-optimised integrated casting: 15% lighter on key load-bearing parts with no loss of strength.

−30%Procurement cost

45 → 20Lead time in days

8,000 h+Hose clamp seal life

0Failures in vehicle verification

"Ningxin Huida not only solved the bottleneck problems with patented technologies, but its dedicated on-site service team also worked with us day and night to tackle the challenges — a partner that truly shares the outcome."
Purchasing Director, Equipment Division, CRRC Group

Pipe clamp and U-clip fasteners manufactured by NXHD

Service

AVIC Optoelectronics — custom single-ear endless clamp

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Aerospace-grade clamp · exclusive supplier after three rounds of technical defence

AVIC Optoelectronics Technology Co., Ltd. (Stock Code: 002179) opened a global tender for a new aviation equipment pipeline upgrade: clamps had to seal reliably across −60 °C to 200 °C, exceed GJB 150.16A vibration requirements, and weigh at least 25% less than conventional products. We passed three rounds of technical defence and prototype testing and were appointed exclusive supplier.

The problems behind the spec

Conventional stainless steel turns brittle below −50 °C, while aviation-grade titanium is expensive and hard to machine — low-temperature toughness and strength had to be balanced.
360° full-circumference sealing demands more contact area, which adds weight; lightweighting risks fatigue fracture under 1,000 Hz vibration.
Monthly demand of 5,000 sets at ±0.05 mm tolerance is beyond the stability of conventional stamping.

Our solution

Material: 17-4PH precipitation-hardening stainless steel with Inconel 718, vacuum aged — impact toughness above 80 J at −60 °C at 40% less cost than a pure titanium design.
Structure: honeycomb-inspired lightening hole arrays with a gradient lug thickness — 32% lighter, vibration fatigue life above 10 million cycles.
Production: TRUMPF 5000 series laser cutting, Zeiss coordinate measuring online inspection and full MES traceability from raw material to finished part, holding dimensional defects below 0.3‰.
A purpose-made quick-installation tool cut clamp assembly from 45 seconds to 18 seconds on the customer's line.

−32%Weight reduction

10 M+Vibration fatigue cycles

±0.05 mmMass-production tolerance

18 sAssembly time, from 45 s

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Changzhi Lin

Five Projects, Five Engineering Problems Solved

Localised replacement of CherryMAX® blind rivets

What we engineered

Result

China Construction Fifth Engineering Bureau — Ulanqab Data Centre fire protection package

What we supplied

Engineering around the environment

All-weather rapid-deployment hoisting system for special vehicles

The three requirements

What we built

CRRC — localising fasteners for CR240E mining trucks

Three engineering breakthroughs

AVIC Optoelectronics — custom single-ear endless clamp

The problems behind the spec

Our solution

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