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Forging + CNC Machining Service

Forging + CNC Machining Service
Forging + CNC Machining Service

Our Forging + CNC Machining Process.

1. Primary Forging Phase (Near-Net Shape Formation)

  • Process: Metal stock (billet or bar) is heated past its recrystallization temperature (hot forging) or formed under extreme pressure (warm/cold forging) using hydraulic or mechanical presses into a near-net shape die.

  • Microstructure & Grain Flow: Compressive forces refine the internal grain structure, aligning continuous grain flow along the geometry of the part. This eliminates internal voids, gas pockets, and porosity.

  • Mechanical Characteristics: High impact toughness, fatigue resistance, and superior tensile strength compared to bar-stock-only machining or casting.

  • As-Forged Tolerances: Typical dimensional tolerances range from ±0.5 mm to ±1.5 mm, with an average surface roughness ($Ra$) of 3.2 µm to 12.5 µm. A designated machining allowance (stock overlay of 1.5–3.0 mm) is retained on functional surfaces.

2. Post-Forging Preparation & Thermal Processing

  • Trimming & Flash Removal: Excess material squeezed out along the die parting line (flash) is mechanically trimmed or sheared off.

  • Heat Treatment (Optional/Application-Specific): Normalizing, annealing, or quench-and-temper cycles are applied to relieve internal residual stresses from plastic deformation and optimize hardness prior to cutting.

  • Descaling: Mechanical shot blasting or chemical pickling removes iron oxide scale generated during hot forging, protecting CNC tooling from premature abrasive wear.

3. Precision CNC Machining & Finishing Phase

  • Setup & Datum Strategy: The forged blank is located in custom fixtures using designated non-critical forged features as datum targets to account for forging draft angles (typically 3° to 7°).

  • Rough Machining: CNC turning, milling, or 5-axis indexing removes excess forging stock allowance down to within 0.3–0.5 mm of final geometry.

  • Finish Machining & Micro-Finishing: Fine-pass CNC operations establish critical engineering features:

    • Precision Features: Bearing journals, threaded holes, seal seats, mating flanges, and strict GD&T tolerances (concentricity, position, perpendicularity).

    • Dimensional Accuracy: Achieves tight manufacturing tolerances down to ±0.005 mm to ±0.012 mm.

    • Surface Roughness ($Ra$): Achieves smooth finish profiles ranging from (Ra) 0.4 µm to 1.6 µm (or finer via subsequent grinding/lapping where required).

Specifications

Process Summary
Metric / Feature As-Forged Blank Post-Machined Forging
Primary Strength Driver Continuous grain flow & high density Retained grain structure in load-bearing core
Dimensional Tolerance ±0.5 mm to ±1.5 mm Down to ±0.005 mm
Surface Finish (Ra) 3.2 µm – 12.5 µm 0.4 µm – 1.6 µm
Critical Features Broad geometry, draft angles present Precision bores, threads, flat mating faces
Ideal Applications General structural frames, non-mating links Engine crankshafts, connecting rods, high-pressure valves