What is Core/cavity machining? is it related to injection mold cost? Share Issue Time 06-23-2017 What is Core/cavity machining? is it related to injection mold cost?All molds must also be customized. Customization includes the placement of cores, cavities, ejectors, cooling lines, etc. The steel used in the tool also impacts cost. Hardened steel molds last the longest and are more expensive to machine. Once done, however, they have a long production life.Click here to learn more about what is core metal /cavity /mold base /cavity machining /complexity /design!Yunpeng mold answer injection plastic molding tool questions for you!