Evaluation method for clay and manufacturing method of extrusion molded body

A manufacturing method of producing an extrusion molded body to be used for manufacturing a honeycomb structural body, the manufacturing method comprising processes of:

• mixing constituent components which contain at least ceramic raw material, binder, lubricant and water to produce a clay;
• extruding the clay by a screw extruder machine and compressing the extruded clay through a resistant tube in the screw extruder machine to produce the extrusion molded body;
• performing a pulse Nuclear Magnetic Resonance to detect at least one of a T1 relaxation time of nuclear spins of water protons magnetically excited for each of a normal part and an abnormality part in the extrusion molded body and a T2 relaxation time of nuclear spins of water protons magnetically excited for each of the normal part and the abnormality part in the extrusion molded body, the normal part being a part where the water is retained with the extrusion molded body, and the abnormality part being a part where the water is seeped on a surface of the extrusion molded body, and performing an evaluation of uniformity of a mixed state and a compression state of the extrusion molded body on a basis of at least one of a difference in the T1 relaxation time between the normal part and the abnormality part, and a difference in the T2 relaxation time between the normal part and the abnormality part;
• and
• determining a mixing condition in the mixing process and a compression condition in the extrusion process on the basis of at least one of the difference in the T1 relaxation time between the normal part and the abnormality part, and the difference in the T2 relaxation time between the normal part and the abnormality part.