Core Principle

Manufacturing cost can increase exponentially with each level of tolerance tightening. This is due to slower machine feeds, extra finishing operations (boring, grinding), more frequent in-process inspection, and expensive metrology equipment (CMM).

Cost Multipliers by Tolerance Level

• Standard Tolerance (±0.1mm / ±0.004"): 1x (Baseline Cost)
• Tight Tolerance (±0.025mm / ±0.001"): ~1.5x - 2.0x Cost
• Ultra-Precision (±0.005mm / ±0.0002"): ~4x - 10x Cost

Design Recommendations

• Apply tight tolerances only to critical functional surfaces (bearing bores, mating faces)
• Use general tolerance blocks (ISO 2768-m) for non-critical features
• Consider the functional requirement: Is the tight tolerance actually necessary?