Custom CNC Aluminum Parts for Robotics Industry — Precision Machining Case Study

In mid-2024, a well-known automotive component manufacturer from Italy contacted our engineering team with a critical sourcing requirement:They needed custom stainless steel fasteners for high-performance automatic transmissions used in electric vehicles (EVs).

These fasteners had to perform reliably under extreme vibration, high torque, and elevated temperatures, where standard off-the-shelf bolts could not maintain structural integrity.

The customer’s main challenge was finding a CNC machining supplier capable of producing tight-tolerance fasteners with controlled surface finishes and consistent mechanical performance across large batches.

With over a decade of experience in precision CNC machining and custom fasteners manufacturing, our company — [Your Company Name] — became their trusted partner for developing, testing, and mass-producing these critical components.

After the first technical meeting and review of the CAD drawings, several key challenges were identified:

• High material performance:The fasteners required AISI 304 and 316 stainless steel, each with specific mechanical and corrosion-resistance properties.

• Dimensional accuracy:The hex socket head and threaded section required tolerance control within ±0.01 mm for accurate torque application.

• Surface finish quality:The automotive client specified a Ra ≤ 0.8 µm finish to prevent micro-cracks under vibration stress.

• Thread precision:The M8 x 1.25 thread had to pass both GO/NOGO and 3D scanning validation to meet ISO 965-2 standard.

• Corrosion and fatigue resistance:The parts were used near the transmission casing, where oil, heat, and moisture exposure were constant.

These strict requirements made the project highly technical and demanding — a challenge our CNC and materials engineering teams were well-prepared to handle.

Our team proposed a multi-phase engineering solution, beginning from DFM analysis to pilot production and quality validation.

We selected AISI 316 stainless steel for its superior corrosion resistance in high-temperature automotive environments.Before production, we performed spectrochemical analysis and mechanical property testing (tensile strength, hardness, elongation) to ensure material conformity.

Material hardness was maintained at HV 230–260, providing the perfect balance between machinability and strength.

Our engineers reviewed the part geometry and optimized the manufacturing process:

• Recommended slight adjustments to undercut depths for better tool reach.

• Simulated machining using MasterCAM to reduce unnecessary tool changes.

• Implemented a two-step threading process (turning + thread rolling) to improve thread fatigue life by 20%.

This stage reduced production cycle time by 18%, improving both cost efficiency and throughput.

The custom fasteners were produced using CNC turning centers (Tsugami TMA8F) combined with Swiss-type lathes for high accuracy.

Each machine was programmed and monitored by skilled technicians to ensure stable output over long runs.

After machining, the fasteners underwent controlled heat treatment to relieve residual stress and enhance tensile strength.

• Heat treatment condition: 420°C for 2 hours, air-cooled.

• Surface treatment: Passivation per ASTM A967, improving corrosion resistance in oil-contact environments.

• Optional coating: Nickel plating for aesthetic appeal (per client request on secondary batch).

Surface roughness after treatment remained at Ra 0.7 µm, and the coating adhesion was tested via ASTM D3359 (Grade 5B).

Quality assurance is the backbone of our CNC machining operations.For this project, every stage of production followed a documented PPAP (Production Part Approval Process) and SPC (Statistical Process Control) procedure.

1. Incoming Material Verification

   • Spectrometer analysis and mechanical certification from supplier.

2. In-Process Control (IPQC)

   • Thread pitch and concentricity inspected every 20 pcs.

   • Automatic optical measurement for head diameter and undercut.

3. Final Inspection

   • 100% visual inspection for surface defects and burrs.

   • CMM measurement for random samples (batch size 200 pcs).

   • Salt spray corrosion test for 48 hours (passed without rust).

   • Torque and tensile testing with digital torque gauge.

Each inspection record was logged into our MES (Manufacturing Execution System) for traceability and shared with the client during shipment.

The first batch of 5,000 custom stainless steel fasteners was delivered within four weeks — two weeks ahead of schedule.After testing and validation, the client reported outstanding performance metrics:

• Torque consistency: ±2% variance across samples.

• Zero defects: No burrs or thread failures reported during assembly.

• Corrosion resistance: Maintained integrity after 96-hour exposure test.

• Dimensional accuracy: 100% parts within drawing specification.

• Batch repeatability: Consistent results across 5 consecutive shipments.

“We have worked with several suppliers before, but none provided the level of precision and communication your team did. Your CNC fasteners exceeded our expectations in both performance and reliability.”
— Procurement Director, Italian EV Transmission Manufacturer

Encouraged by these results, the client extended the partnership for additional custom threaded inserts and titanium bolts for their next EV platform.

This project fully utilized our company’s advanced CNC machining capabilities and strict quality management system.

We also implemented a digital inspection workflow using barcode tracking, ensuring full visibility of every production stage — from raw material to packaging.

Given the sensitivity of surface finishes and thread quality, our packaging process was designed with care:

• Each fastener was separated by anti-scratch foam dividers.

• Vacuum-sealed in groups of 50 pcs with silica gel packets.

• Export-grade cartons labeled with QR codes for batch traceability.

• All shipments were handled via DHL Express and sea freight, depending on customer urgency.

Lead time for standard reorders: 10–12 working days.

Following this successful project, similar custom stainless steel fasteners have been applied to:

• EV Powertrain Systems
  (Battery case bolts, inverter housing screws)

• Heavy-Duty Machinery
  (Vibration-resistant locking bolts)

• Marine Equipment
  (Anti-corrosion threaded connectors)

• Industrial Robotics
  (Precision alignment pins and torque fasteners)

This showcases how our CNC machining expertise and material knowledge allow us to support various industries where strength, reliability, and precision are essential.

1. Expert in Custom Machined Fasteners

   • 17+ years of experience manufacturing stainless steel, titanium, and alloy fasteners.

2. Advanced Equipment Fleet

   • Swiss-type lathes, 5-axis centers, automatic thread rollers.

3. Quality Without Compromise

   • Certified ISO 9001 / IATF 16949 with full inspection documentation.

4. Flexible Order Volume

   • Prototype to mass production, no MOQ limit.

5. Global Customer Trust

   • Clients in Europe, USA, Japan, and Australia across automotive and robotics sectors.

This Custom Stainless Steel Fasteners Case Study exemplifies how a technical partnership and precision machining expertise can transform complex engineering requirements into reliable, production-ready solutions.

Through the integration of CNC precision, quality control, and customer-focused engineering, [Lock Technology(shenzhen)Co.,LTD] successfully helped the client improve transmission reliability, reduce production time, and strengthen their EV product competitiveness.

Whether you require custom bolts, nuts, shafts, or non-standard precision fasteners, our engineering team can deliver tailored CNC machining solutions that meet your toughest requirements — every time.

[Lock Technology(shenzhen)Co.,LTD] — Precision You Can Trust, Performance You Can Measure.

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