Evaluating the Roughness According to the Tool Path Strategy When Milling Free Form Surfaces for Mold Application

The mold manufacture has a direct influence on the lead time, costs and quality of plastic products. Milling is the most important machining process in this industry. Due to some limitations on the milling operations, the surface roughness required for a mold is frequently only achieved by hand finishing. Even using updated technologies such as High Speed Milling, which improves the machined surface quality, the hand finishing is still required and it brings some drawbacks such as costs, time and geometrical errors. Today, any CAM software offers some different tool path strategies to milling free form geometries. However, the users must have the know-how to choose the strategies according to geometry complexity, cutting tool geometry and its contact on the machined surface. Choosing an optimum strategy is a rather difficult task to do on the shop floor. This topic is still not very well explored. The current work investigates different tool path strategies for milling a mold cavity during finishing operation. A mold cavity was manufactured and the results show that the tool path strategies have a great influence on the real milling time, surface roughness and hand finishing time and also show that the traditional roughness parameters are not adequate to measure the roughness in such applications.