Cover part for air cleaner was injection molded at a speed of 100 rpm using a 2,500-ton injection-molding machine (ND2500 (screw diameter: ϕ140, maximum injection pressure: 1,640 kg/cm 2, maximum injection rate: 1,370 cm 3 /s), Woojin Selex Co., Ltd., Anyang, Korea) equipped with a 1 : 5 …