: Sheet metal industries use different forming methods which are based on using dies and punches with high dimensional and geometrical accuracy. These methods usually use in mass production, but when a few number of parts is needed, methods based on dies is not economic. Through possible process, incremental sheet metal forming (ISMF) can be a certain process for manufacturing parts in low production volume. Incremental sheet forming with turning machine called spinning has been used from decades and many researches in this field have been done. Incremental sheet forming with CNC milling machine is a new research field that both experimental and analytical works has been done on it. In this process a tool with spherical head install on spindle of milling machine and by moving on the controlled path while contacting a blank that fixed from periphery, forms it in the locally and consequently manner. Incremental sheet forming is divided into two categories: single point incremental forming and two point incremental forming. Studying related publications shows that works done in TPIF field is Inadequate. On the other hand these publications don’t mention to the details. One of limitation of process that researchers don’t research about it, is forming asymmetric parts with negative wall incline by incremental forming. These parts can’t be formed by conventional forming processes because of its special geometry. So it was a need for carrying a research on forming of this parts and feasibility of forming them by experimental tests. Results of this research helps future works that can be done experimentally and analytically. In this work after designing tests using complete method and supplying required tools contain: forming tool, supporting tool and blank-holder, sheet parts with negative wall incline was formed by CNC milling machine. During this tests effect of processes parameter such as forming tool diameter, feeding, type of path and lubricant on achievable forming depth that is one of important parameters, was investigated. Also for estimating applied force to the forming tool, before doing experimental tests, simulation of process was done in finite element software. The Results show that forming sheet parts by using two point incremental forming is possible. y using a tool with certain diameter and low feed, achievable forming depth improved and type of path has a negligible effect on forming depth. Simulation results show that by decreasing tool diameter, forming force increases. Key words : incremental forming, sheet metal, CNC milling machine, negative wall incline
