A diagnostic system includes a tool to perform machining on a workpiece, a test piece to be subjected to test machining by the tool for abnormal detection, a sensor to generate sensor data representing a physical quantity generated in the test machining, and circuitry. The test piece is different from the workpiece. The circuitry controls the tool to perform the test machining in each cycle of machining on the workpiece and calculates a degree of abnormality from the sensor data of the test machining. The test machining is performed on the test piece under a test machining condition corresponding to a machining condition of the machining on the workpiece.

Methods and apparatus for producing and assessing at least part of an object (2), the methods comprise: performing, using Additive Manufacturing apparatus (8), an Additive Manufacturing process to produce a test specimen (30, 34, 38) and at least part of an object (2); performing, using micro-tomography apparatus (40), on the test specimen (30, 34, 38), a micro-tomography process to create a digital model (50) of the internal structure of the test specimen (30, 34, 38); determining whether or not the model (50) satisfies one or more criteria; and, if the model (50) satisfies the criteria, determining that the at least part of the object (2) produced by performing the Additive Manufacturing process is acceptable, or, if the model (50) does not satisfy the criteria, determining that the at least part of the object (2) produced by performing the Additive Manufacturing process is not acceptable.

An evaluation work piece includes at least one of a part (B) or (G), and at least one of a part (A), (C), (D), (E), or (F). (A) is a vertical level difference part. (B) is a direction reversing part at which a direction of movement of a tool in a height direction is reversed when the tool is used for machining of a three-dimensional object including a curved surface. (C) is a corner part at which a direction of movement of the tool changes. (D) is a flat surface part. (E) is a boundary part between a flat surface and a curved surface with a changing curvature. (F) is a curved surface part having a curved surface with a changing curvature. (G) is a curved surface part at which command points are aligned regularly between adjacent tool paths on a curved surface. At least one of the part (B) or (G) is included in a cut spherical body part. A reference surface for a three-dimensional measuring machine is arranged around the cut spherical body part. At least one of the part (A), (C), (D), (E) or (F) is arranged outside the reference surface.

An evaluation work piece comprises at least one of parts (A) to (G) as follows on a surface machined by a machine tool: (A) a vertical level difference part having a vertical level difference, and flat surfaces arranged on both sides of the vertical level difference; (B) a direction reversing part at which a direction of movement of a tool in a height direction is reversed when the tool is used for machining of a three-dimensional object including a curved surface; (C) a corner part at which a direction of movement of the tool changes; (D) a flat surface part; (E) a boundary part between a flat surface and a curved surface with a changing curvature; (F) a curved surface part having a curved surface with a changing curvature; and (G) a curved surface part at which command points are aligned regularly between adjacent tool paths on a curved surface.