f Degree of machining f (fully machined)
Degree of machining f (fully machined) · Fundición (ISO 10135) · ISO 1101
Example in plan
How to interpret it
On the drawing, “Grade f on precision casting” states a degree of machining f (fully machined) requirement.
What controls
Degree of machining stating that all surfaces of the part are machined, so that no as-cast surface remains on the final product. It implies machining allowance on every face, more starting material, more machine time and fixturing capable of holding the part in several orientations without losing reference. It is uncommon, and when it appears it usually responds to inspection, cleanliness or coating requirements, not to the part needing precision everywhere.
How to verify
The entire part is inspected to machining criteria: conventional instruments for individual dimensions and a CMM or portable measuring arm for the whole, always referencing the drawing's datum reference frame. An intermediate check after full roughing and before finishing is advisable, to detect in time whether any face is running out of material.
Common mistakes when interpreting it
- Quoting the part as if it were partially machined: the fully machined grade changes machine time and starting weight.
- Assuming that machining everything eliminates internal casting defects: the porosity is still there and can break out as material is removed.
- Forgetting that intermediate locating faces are also machined at the end, and losing reference between setups.
How to get it in the workshop / if it comes out of tolerance
Plan the sequence of setups before touching the part: if everything has to be machined, every face used as a locator will end up being machined later, and you must ensure the reference is maintained. Confirm there is allowance on all faces, not just the obvious ones. Expect more roughing and, on parts with residual stresses, an intermediate stress relief so the part does not move between operations.
If a face comes up short on allowance, re-establish the work offset to redistribute: with the whole part machined there is more freedom to shift everything than when as-cast faces must keep their position. If the part moves between roughing and finishing, the cause is residual stress: add a stress relief in between and leave sufficient finishing passes. If porosity breaks out on several faces, the problem is in the pour and must go back to the foundry.
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