【正文】 et surface based tool path generation[6]， nonconstant parametric tool path generation[7]， Cbased tool path generation[8]， etc. Different methods have different application fields. It would be of great signicance if these algorithms were industrially available. However， except for the constant scallop height method， so far few of these newly emerged methods are widely used in industry. One of the main reasons is that there is no mercial platform available in practice for each of these methods. In the implementation process of a new tool path generation algorithm， after obtaining geometric data from CAD models， the users have to determine and calculate many parameters， from tool path patterns to the engaging and retracting methods， from scallop heights to forward steps. Because of the large amount of calculations， it is difcult for a userdesigned system to include many optional functions， which are necessary in practice， for example， the options for selecting the on， inside and outside relations between tool and the boundaries of cutting areas， the variant engaging and retracting methods， etc. This made it inconvenient to use in industry. Machining of steep regions on freeform surfaces is an important topic in machining of freeform surfaces. A new tool path generation algorithm， adaptive isoplanar tool path generation method [9]， with which steep regions on freeform surfaces are adaptively machined， was recently developed. However， similarly to many newly emerged methods， it has not yet been used in industry because no mercial CAD/CAM platforms are currently available and the userdeveloped system is not robust enough for industrial applications. To solve this problem，this paper presents an easier but powerful method to implement the new tool path generation algorithm by integrating it in the Pro/Engineer (Pro/E) mercial system. With this strategy， other than conducts detailed putations for parameters such as scallop heights and forward steps， or designing the noncutting function such as engaging and retracting methods， which are routine in every tool path generation process， the implementation utilizes existing tool path generation templates of Pro/E to generate the required tool paths. This makes the generation process easier and the tool paths generated were more practicable because the integration is relieved of the timeconsuming routine calculation and the entire cutting and noncutting functions of the mercial system bee transparent to users. In this paper， Pro/E is taken as the implementation platform. Not forsaking generality， the implementation could also be conducted in other mercial systems， such as Unigraphics，since similar functions of Pro/E are available in other systems as well. The second section of the paper is an introduction of the technologies for machining of steep regions in mercial systems and the introduction of the adaptive isoplanar tool path generation method. Detailed implementation is presented in Sect. 3. To test the result， in addition to the machining simulations presented in Sect. 4， real cutting tests on plastic workpieces are carried out on a 3axis CNC machine tool equipped with a FANUC Professional 3 CNC controller. The last section provides a short conclusion.2 Machining of steep regions on freefrom surfacesMachining of steep regions is an important topic in machining freeform surfaces. This function is available in many mercial CAD/CAM systems such as Pro/E， Unigraphics， SurfCAM， WorkNC， etc. Figure 1 shows the machining of at and steep regions on freeform surfaces with the(a) (b)Fig. 1. a Machining of at regions (0 –30 ) with Mastercam b Machiningof steep regions (30 –90 ) with MastercamFig. 2. a Machining of at and steep region b Machining of steep region [11]mercial CAD/CAM system called Mastercam [10]. Similar machining abilities are also available in other example， Unigraphics has two special tool path generation templates “ZLEVEL_PROFILE_STEEP” and “CONTOUR_AREA_DIR_STEEP” for machining of steep regions [11]. Another strategy used to machine steep regions， as shown in Fig. 2， is also provided by Unigraphics. Surface regions created from steep faces and nonsteep faces may be used in separate operations to avoid generating large scallops that can result when used in a single operation [11]. The steep region is created bya specified cut direction vector and this region is used in a subsequent operation to remove large scallops. Adaptive isoplanar tool path generation [9] provides a different way to machine at and steep regions on freefrom this method the surfaces are rst divided into different regions according to their slopes. After the surfaces are partitioned，two different tool path planning strategies， regionbyregion machining or globallocal machining， can be applied to machine theat and steep regions， as shown in Fig. 3. The second strategy shares some similarities with the functions that Unigraphics provides but is different. In regionbyregion machining， by using planesurface intersections with different intervals in different regions， the side steps of tool paths in each region are made adaptive to the surface slopes. In globallocal machining， the surface is rst machined with global tool paths that are generated with the largest plane intervals outside of the light regions. Then， in each light region where the scallop heights exceed the tolerance，extra local tool paths are inserted between the global ones. With these strategies， the shortest tool path length is obtained to machine the freeform surfaces.3 Implementation Strategy of implementationIn order to take advantage of the putational abilities that the mercial system provides， the basic strategy of the implementation is to make full use of the rich resources of Pro/E as much possible so that the intensive routine putations required in implementing the new algorithm c