Classifying Costs as Materials, Labor, or Factory Overhead Indicate whether each of the following costs of an automobile manufacturer would be classified as direct materials cost, direct labor cost, or factory overhead cost: Cost Classification a. Automobile engine b. Brake pads c. Depreciation of robotic assembly line equipment d. Glass for front and rear windshields e. Safety helmets and masks for assembly line workers f. Salary of quality control inspector 9. Steering wheel h. Tires 1. Wages of assembly line workers