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Medium-Bore Motor Frames
Jiangsu Yufeng Electric Co., Ltd. supplies medium-bore motor frames across the 50–120 mm diameter range, serving the core of the general-purpose industrial motor market. These frames are produced through a fully integrated process chain: precision stamping, robotic welding with seam tracking, multi-axis CNC machining of mounting interfaces, and automated surface treatment. The medium-bore platform is engineered for high-volume consistency, with process controls that maintain critical dimensional tolerances across millions of units. With 40 years of manufacturing heritage and capacity exceeding 5 million units per year, Yufeng delivers frames that meet IEC 80–132 and NEMA 56–180 specifications, with custom configurations available for specific mounting and interface requirements.
Progressive stamping with in-line gauging maintains Cpk ≥ 1.67 on bore diameter, flange flatness, and hole position across all production batches.
Optimised blanking layouts achieve scrap rates below 8 %. Material grades include DC01, SPCC, and S235JR with thickness from 2.0 mm to 4.0 mm.
Robotic MAG welding with seam tracking and penetration monitoring. MPI inspection available for critical applications requiring full weld validation.
Standard zinc phosphate + e-coat delivers 480 h salt spray resistance. Powder coating and zinc-rich primers available for extended corrosion protection.
Product specifications
| Bore diameter range | 50 mm – 120 mm |
| Frame size equivalents | IEC 80, 90, 100, 112, 132; NEMA 56, 140, 180 |
| Bore tolerance | ISO H7 (standard), J7, or custom fits on request |
| Wall thickness | 2.0 mm – 4.0 mm (dependent on size and material) |
| Material grades | DC01, SPCC, S235JR |
| Flange flatness | ≤ 0.06 mm per 100 mm (post-machining and stress relief) |
| Concentricity (bore to pilot) | ≤ 0.10 mm |
| Surface coating | Zinc phosphate + cathodic e-coat (standard); powder coating or zinc-rich primer optional |
| Mounting configurations | B3, B5, B14, or custom flange patterns |
Production infrastructure
- Dedicated stamping lines: Progressive dies optimised for medium-bore frames with automated die changeover, reducing downtime between batches.
- In-process verification: Automated gauging stations monitor bore diameter, flange parallelism, and hole position at each stage of production.
- Weld quality system: Robotic welding with real-time penetration monitoring and scheduled cross-section analysis for weld integrity verification.
- Coating process control: E-coat bath parameters monitored continuously to ensure consistent film thickness and adhesion across all parts.
Supply chain & logistics
- Material traceability: Steel coils procured from certified mills with full traceability to heat numbers and mechanical test reports.
- Inventory strategy: Safety stock maintained for standard frame sizes, enabling lead times of 12–18 working days for volume orders.
- Packaging systems: Returnable steel racks for high-volume shipments; corrugated cartons with anti-rust VCI film for smaller quantities.
- Export readiness: ISPM 15 certified wooden crates and full documentation for international shipments, including customs clearance support.
Application fields
- General-purpose industrial motors: Pumps, fans, compressors, and conveyors — forming the backbone of factory automation and process industries.
- HVAC and building services: Air handling units, chillers, and cooling towers requiring reliable, long-life motor frames in continuous operation.
- Agricultural equipment: Irrigation pumps, grain handling systems, and ventilation fans for livestock and crop processing facilities.
- Material processing: Crushers, mixers, and grinding mills where frame rigidity is essential for bearing life and vibration control.
For custom flange configurations, special bore tolerances, or application-specific coatings, Yufeng provides engineering review and sample verification prior to production. DFM feedback is provided within 48 hours.
Engineering supportFrequently asked questions
Our medium-bore range covers IEC frame sizes 80, 90, 100, 112, and 132, as well as NEMA 56, 140, and 180. Custom bore diameters within the 50–120 mm range can also be accommodated with appropriate tooling adjustments.
Wall thickness ranges from 2.0 mm to 4.0 mm, depending on the frame size and material grade. Thicker walls are used for larger frames to maintain structural rigidity; thinner walls for smaller frames to reduce overall weight.
We employ progressive stamping dies with in-line gauging, automated welding fixtures with positional repeatability, and CNC machining with tool wear monitoring. Process capability studies (Cpk) are performed regularly on all critical dimensions.
Standard coating is zinc phosphate + cathodic e-coat (20–30 μm). For outdoor or aggressive environments, we offer powder coating (60–80 μm), zinc-rich epoxy primers, and nickel plating. Salt spray resistance up to 720 hours is achievable.
We provide EN 10204 3.1 material certificates, full dimensional inspection reports, and coating thickness verification. PPAP level 3 documentation is available for automotive and high-reliability applications.
Manufacturing Solutions
We offer full-process manufacturing capabilities from steel processing to finished product delivery, supported by stamping lines, automated welding equipment, machining facilities, and inspection instruments. Backed by an engineering team with an average of over 20 years of experience, we provide technical support from development to mass production.
With 40 years of focus on motor housing manufacturing, we have served more than 50 customers and achieved an annual production capacity of over 5 million units. Guided by quality, efficiency, and fast response, we are committed to delivering high-precision and high-reliability motor housing solutions.
