Key Control Points in the Machining of Radiator Fins for Aluminum Plate-Fin Heat Exchangers

In radiators, fins are the most fundamental components of a plate-fin heat exchanger. Heat transfer is primarily accomplished through the fins, which serve as both heat exchange surfaces and structural supports. The core differences among various fin types lie in the trade-off between heat transfer efficiency and flow resistance.

In aluminum plate-fin heat exchangers, the fins (produced by aluminum foil stamping/forming) are the critical heat exchange elements—thin, dense, high-precision, and prone to deformation. Their machining control directly determines heat dissipation efficiency, brazing quality, and product service life.

The following sections present the key control points throughout the entire manufacturing process.

Material: 3003 / 3102 / 1100 aluminum alloy foil (soft O-temper), thickness 0.14 – 0.20 mm

Key inspections:

(1)Thickness uniformity: ±0.005 mm, free from edge waviness, undulations, or scratches

(2)Surface condition: No oil contamination, oxidation, creases, or inclusions

(3)Mechanical property: Elongation ≥15% to ensure formability without cracking

Precision requirements

(1)Wave height / tooth height: ±0.05 – 0.1 mm

(2)Wave pitch / tooth pitch: ±0.05 – 0.1 mm

(3)Fin length: ±0.1 – 0.2 mm

(4)Fin flatness: ≤0.5 mm/m, free from twisting or collapsing

Tooling and equipment

(1)Die clearance: 0.005 – 0.01 mm; cutting edges sharp and intact without chipping

(2)Feed accuracy: ±0.02 mm, using servo or precision roller feed

(3)Speed matching: low, stable forming speed for thin fins to prevent tensile deformation

Common defect control in fin stamping

(1)Cracks / splits: Reduce speed, increase lubrication, check material elongation

(2)Waviness / twisting: Adjust material clamping force, level, and reinforce support

(3)Burrs: Repair the die, control clearance, and remove chips promptly

(4)Uneven height: Adjust stamping depth and die parallelism

(1)Plain fins – Focus on flatness, straightness, and clean cut ends

(2)Corrugated / sine-wave fins – Uniform wave height and pitch; no collapse or spring-back

(3)Serrated fins (most common) – Consistent tooth height and pitch; burr-free and non-sticking cuts without missing teeth; tooth tips free from collapse or tilt

(4)Perforated / louvered fins – Precise hole positions and louver angles; no tearing, no deformation, and smooth hole edges

(1)Post-forming: Deburring and light reshaping

(2)Cleaning sequence: Alkaline wash → acid wash → pure water rinse → drying

(3)Result: Free from oil, aluminum powder, and water spots

(4)Drying: Thorough drying at 100 – 120 °C to prevent oxidation

(5)Protection: Clean environment, no direct contact, no stacking pressure, anti-static handling

(1)Use a precision cut-off die; length tolerance ±0.1 mm

(2)Cuts must be perpendicular, burr-free, and without edge collapse

(3)Inspections: first-piece full check + in-process patrol + last-piece full check

(1)Use dedicated trays/fixtures, single layer or soft separators to avoid crushing

(2)Handle gently; no stepping or stacking pressure

(3)Re‑inspect before stacking: no deformation, no oil contamination, dimensions meet requirements

(4)Fit with separators and side bars: gap ≤0.05 mm, no clearance

(1)Fins shall have no cracks, indentations, or severe scratches

(2)Fin geometry must be regular; no crushing, stretching, or twisting

(3)Uniform spacing; adjacent spacing deviation ≤0.1 mm

(4)Surface clean, dry, and free from oxidation

(1)First article: Full dimensions (thickness, height, pitch, length, flatness)

(2)In‑process: Every 30 – 50 pieces – sample check wave height, wave pitch, and appearance

(3)Finished product: 100% appearance inspection; batch sampling or full inspection for dimensions