An automotive parts supplier plans to double its workforce in Rowan, Caldwell and Catawba counties. Magna Composites plans to hire 327 workers over the next three years at its plants in Salisbury, Lenoir and Newton and spend $10 million to expand those facilities. The company makes plastic parts for trucks, cars, golf carts and home appliances. Magna says orders have been picking up. Magna acquired the three North Carolina plants when it bought part of Meridian Automotive Systems last year. Shortly after that, Meridian filed for bankruptcy. The company said losing a major contract put it on rocky footing. The jobs will pay an average salary of $33,000. The state is offering Magna up to $1 million in tax breaks if the company makes good on its hiring promises.