diff --git a/SurfRoughing.cpp b/SurfRoughing.cpp
index 02562f2..f9b9e7c 100644
--- a/SurfRoughing.cpp
+++ b/SurfRoughing.cpp
@@ -1367,7 +1367,7 @@ SurfRoughing::GetRaw( ISurfTriMesh* pStmRaw) const
 
 //----------------------------------------------------------------------------
 bool
-SurfRoughing::GetSfrByRawIntersection( ISurfFlatRegion* pSfrInt, IntersParPlanesSurfTm IPPStm, double dDist) const 
+SurfRoughing::GetSfrByRawIntersection( ISurfFlatRegion* pSfrInt, const IntersParPlanesSurfTm& IPPStm, double dDist) const 
 {
   // controllo dei parametri
    if ( pSfrInt == nullptr)
diff --git a/SurfRoughing.h b/SurfRoughing.h
index 3cbcdae..cab836e 100644
--- a/SurfRoughing.h
+++ b/SurfRoughing.h
@@ -90,7 +90,7 @@ class SurfRoughing : public Machining
                        const ICurveComposite* pRCrv, bool bSplitArcs, bool bNoneForced,
                        Point3d& ptP1, double& dElev) ;
       bool GetRaw( ISurfTriMesh* pStmRaw) const ;
-      bool GetSfrByRawIntersection( ISurfFlatRegion* pSfrInt, IntersParPlanesSurfTm IPPStm, double dDist) const ;
+      bool GetSfrByRawIntersection( ISurfFlatRegion* pSfrInt, const IntersParPlanesSurfTm& IPPStm, double dDist) const ;
       bool GetActiveSurfaces( INTVECTOR& vSurfId) const ;
       double GetRightFeed( const Vector3d& vtMove, const Vector3d& vtTool) const ;
       double GetRadiusForStartEndElevation( void) const ;