Iso | 8015 Tolerance Table ((hot))

"If the hole is perfectly round, and your shaft is oval," Elias said, "you will have vibration. At 20,000 RPM in a jet engine, that vibration becomes heat. That heat becomes expansion. And expansion..." Elias snapped his fingers. "...becomes a seizure."

Elias picked up a stamp from his desk. REJECTED. He pressed it down onto Jax’s work order with a decisive thud .

"There," Elias said. "Geometric tolerancing. ISO 8015 separates size from form. You have size—you are within the h6 limits. But your shaft is not perfectly round. It has an ovality of 7 microns."

Jax exhaled. "See? It's within range. It's not over fifty. It’s good." iso 8015 tolerance table

General linear and angular tolerances (when not individually specified) are found in:

Jax nodded, chastened but enlightened. He picked up the shaft, heavier now with the weight of knowledge.

Thus, ISO 8015 forces you to explicitly specify form controls if needed – it changes how you interpret the “table” of general tolerances. "If the hole is perfectly round, and your

"Take it back," Elias said. "Turn it again. Aim for the upper limit of the tolerance zone to account for the ovality. Use the table to predict the assembly condition. Don't guess. Calculate."

– General tolerances for linear and angular dimensions

| Standard | Purpose | Has table? | |---|---|---| | ISO 8015 | GPS rules, independency principle | ❌ No | | ISO 286 | Limits and fits (H7/g6, etc.) | ✅ Yes | | ISO 2768-1 | General linear/angular tolerances | ✅ Yes | | ISO 2768-2 | General geometrical tolerances | ✅ Yes | And expansion

Perfect.

A tolerance of size (e.g., ±0.1) does not automatically control the form (e.g., straightness or circularity) unless the "Envelope Requirement" symbol Ⓔ is used.

"Precisely," Elias said. "For a 50mm nominal size, the h6 tolerance dictates an upper deviation of zero and a lower deviation of minus sixteen micrometers. Sixteen microns, Jax. That is less than the width of a human hair."

"Sir?" Jax asked at the door. "Why 16 microns? Why not 15 or 20?"