Machine for the production of sand moulds comprising a machine structure with a moulding chamber, a front plate and a rear plate, said front plate and rear plate being arranged for pressing sand within said moulding chamber so as to form a sand mould, said front plate and rear plate being arranged for receiving respective pattern plates for providing front and rear surfaces of the sand mould with corresponding patterns, characterized in that the machine further comprises a robot arm arranged for replacing the pattern plates, said robot arm being attached to the machine structure, wherein the robot arm comprises vertical drive means for displacing the robot arm vertically, and three pivot joints (62, 63, 64) for pivoting three corresponding arm segments (62A, 63A, 64A) around corresponding vertical axes, said robot arm comprising an electric motor for driving the robot arm vertically, and three electric motors (62M, 63M, 64M) each arranged for driving a corresponding one of said three arm segments (62A, 63A, 64A) to pivot with respect to the corresponding pivot joint (62, 63, 64), wherein said robot arm has a proximal end at which it is attached to the machine structure, and a distal end (6") which is provided with means for retaining a pattern plate, and wherein said pivot joints comprise a proximal joint, an intermediate joint and a distal joint, said distal joint being arranged for pivoting a distal arm segment with respect to an intermediate arm segment, wherein the electric motor arranged for operating said distal joint is placed away from said distal joint, and wherein said robot arm comprises drive means placed within said intermediate arm segment so that said electric motor arranged for operating said distal joint can operate said distal joint through said intermediate arm segment, to pivot said distal arm segment with respect to said distal joint. characterized in that the machine further comprises a robot arm arranged for replacing the pattern plates, said robot arm being attached to the machine structure, wherein the robot arm comprises vertical drive means for displacing the robot arm vertically, and three pivot joints (62, 63, 64) for pivoting three corresponding arm segments (62A, 63A, 64A) around corresponding vertical axes, said robot arm comprising an electric motor for driving the robot arm vertically, and three electric motors (62M, 63M, 64M) each arranged for driving a corresponding one of said three arm segments (62A, 63A, 64A) to pivot with respect to the corresponding pivot joint (62, 63, 64), wherein said robot arm has a proximal end at which it is attached to the machine structure, and a distal end (6") which is provided with means for retaining a pattern plate, and wherein said pivot joints comprise a proximal joint, an intermediate joint and a distal joint, said distal joint being arranged for pivoting a distal arm segment with respect to an intermediate arm segment, wherein the electric motor arranged for operating said distal joint is placed away from said distal joint, and wherein said robot arm comprises drive means placed within said intermediate arm segment so that said electric motor arranged for operating said distal joint can operate said distal joint through said intermediate arm segment, to pivot said distal arm segment with respect to said distal joint.