A method for manufacturing a linear actuator includes inserting a portion of a thrust member of the actuator into a casting portion of a molding apparatus. The control unit corrects the preset second exposure amount based on information about a difference between the charging voltage output from the charging unit and a predetermined charging voltage andor information about a difference between the developing voltage output from the developing unit and a predetermined developing voltage. The method for conserving space while displaying or storing wheelbarrows is provided. The parallelizing lens allows delivery of a high current ribbon ion beam to the work piece with energy that can extend down to as low as approximately 200 eV. Finally, the printing machine is run up to a fourth speed for continuous printing when the separation of rejects is concluded.