Some specialties require less strength than others because of hoists and other equipment used on the job. Many are members of a labor union. Unions include the International Association of Machinists and Aerospace Workers and the Amalgamated Transit Union. Two other unions include the International Union, United Automobile, Aerospace, and Agricultural Implement Workers of America and the Transport Workers Union of America. Still other unions include the Sheet Metal Workers' International Association and the International Brotherhood of Teamsters.
Wages vary with level of training, experience and location.
Entry level wages may be lower. Pay varies with the employer's geographic location and industry. It also varies with the worker's skill and experience. Beginning apprentices earn from 50 to 75 percent of the rate of skilled workers. Apprentices receive pay increases about every six months until they complete their apprenticeship.