Machining Parts

A: Q235B is ordinary carbon structural steel with yield strength ≥235MPa, suitable for small and medium transformers. Q345B is low-alloy high-strength steel with yield strength ≥345MPa, offering higher load capacity for large transformers and high short-circuit withstand requirements. Both are weldable; Q345B offers better low-temperature impact toughness suitable for cold regions. Our company can recommend optimal material based on transformer capacity and operating conditions.

A: During clamp welding, residual stress is generated in the weld area. If not eliminated, it may cause gradual deformation during long-term operation, affecting core compression force. Annealing (or vibratory stress relief) eliminates over 90% of residual stress, ensuring long-term dimensional stability and preventing core loosening.

A: Tank flange flatness is generally required to be ≤0.3mm/m (≤1mm over total length). Flange flatness directly affects tank sealing performance: excessive flatness deviation causes uneven seal compression, resulting in leakage where compression is insufficient or permanent seal deformation where compression is excessive. Our company uses gantry milling for precision finishing of flange surfaces to ensure reliable sealing.

A: Common surface treatments and applications:
Painting: Conventional indoor/outdoor transformers, moderate cost, color options (RAL), three-layer protection (primer + intermediate + topcoat)
Hot-Dip Galvanizing: Severe corrosive environments (coastal, chemical plants), high corrosion resistance, higher cost, limited color
Dacromet: High corrosion resistance, hydrogen embrittlement-free, suitable for high-strength bolts
Stainless Steel: Coating-free, suitable for flanges, grounding terminals
Recommendation: Painting for conventional transformers; hot-dip galvanizing or stainless steel for marine/heavy pollution environments.

A: Yes. We have a complete process for processing according to customer drawings:
1. Customer provides drawings (PDF/DWG format)
2. Technical department conducts drawing review (process feasibility, manufacturability)
3. If tooling is required (e.g., special-shaped stamped parts), tooling cost confirmed with customer
4. Sample production and submission for customer approval
5. Mass production
We have experience processing thousands of non-standard drawings; custom orders are welcome.

A: Our gantry milling machining range: length × width × height ≤ 8000mm × 2500mm × 2000mm. Beyond this range, components can be fabricated in sections and assembled on-site. For transport, oversized/overwidth items require special transport permits; we coordinate with logistics companies in advance to ensure compliant and safe transport.

A: We use three layers of assurance:
1. Fixture Positioning: Special fixtures for key processes to eliminate manual layout errors
2. CNC Equipment: CNC machining centers and CNC press brakes ensure repeatability
3. SPC Control: Regular sampling during batch production with control charts to detect deviations early
Batch product dimensional tolerance can be stably controlled within ±0.2mm.

A: Load-bearing welds (such as lifting lugs, base, main clamp welds) require 100% non-destructive testing. Inspection methods based on weld thickness and location:
Ultrasonic Testing (UT): For internal defects in thick plates, per GB/T 11345
Magnetic Particle Testing (MT): For surface and near-surface crack detection, per GB/T 26951
Radiographic Testing (RT): For internal defects in critical welds, per GB/T 3323
All inspectors are certified; inspection reports are provided with shipments.

A: Typical delivery lead times:
Simple Parts (flanges, small brackets): 15-20 days
Complex Parts (clamps, tank structural components): 25-35 days (including material procurement)
Large Volume Orders: 45-60 days
Expedited service available (subject to schedule coordination), with lead time reduction of 30-40%.

A: Yes. For replacement components for aging transformers or when drawings are unavailable, we can arrange engineers to perform on-site measurements and generate machining drawings for customer approval before production. We have extensive experience with on-site measurement and retrofit projects at multiple power plants and substations.