t MIN Minimum wall thickness

How to verify

Ultrasonic thickness gauge on the accessible face, which is the specific tool for walls with a closed internal cavity; thickness caliper or long-jaw vernier caliper when there is access from both sides. On complex parts, an external 3D scan combined with the core model, or outright CT scanning on critical parts, makes it possible to map the complete thickness. Sectioning a part from the first pour and measuring the cross-section is still the clearest method when one can be sacrificed.

Workshop guideline values

General

On the order of 5–8 mm on walls of medium-size iron and steel sand castings.

Accuracy

On the order of 3–5 mm with controlled molding and alloys with good castability.

High precision

Below 3 mm only in processes such as die casting, investment casting or permanent mold.

Guidance only: the drawing's value always wins.

Common mistakes when interpreting it

• Reading the minimum thickness as a nominal dimension and machining to that value: it is a limit that must not be reached from below.
• Checking it before machining and not after, which is when the wall actually ends up at its final thickness.
• Correcting a machining work offset to save another dimension without rechecking what happened to the wall thickness.