Machining tolerances for medical molds must be controlled within **±2 μm**-equivalent to one-thirtieth of the diameter of a human hair. This is achieved primarily through the following processes:
1. Ultra-precision machining equipment
Five-axis machining centers: When machining micro-holes (0.3 mm in diameter) for medical catheter molds, these centers achieve a positioning accuracy of ±3 μm and a hole-wall roughness of Ra ≤ 0.1 μm, preventing medication retention caused by rough surfaces.
Micro-EDM (Electrical Discharge Machining): A Φ0.1 mm electrode is used to machine barb structures for medical needle molds. With a machining gap of less than 5 μm, the process ensures burr-free barb edges, thereby minimizing tissue damage during puncture.
2. "Nanoscale" surface treatment
Diamond-like carbon (DLC) coating: A 2–3 μm thick DLC coating is deposited on the mold cavity surface. This achieves a surface hardness of 2000 HV and reduces the friction coefficient to 0.02, lowering the demolding force for medical film products by 40%. Additionally, the coating's hydrophobicity minimizes medication residue (residual amount < 0.1 μL/cm²).
Electropolishing (EP): Electrochemical action dissolves microscopic surface asperities, reducing surface roughness from Ra 0.2 μm to Ra 0.05 μm to create a near-mirror finish; this is particularly suitable for molding medical optical components (such as endoscope lenses).