Aceleratin, deceleration

Greetings,
We have a Sinumerik 840D control on a gantry type 5 axis water jet machine. THe C and Brotating axis are at the end of Z axis.We are cutting formed sheet metal.
We are havingdwell marks at tangencies along the cutter path. The programmed machining feed rate along the cutter path is 24 inches per minute. The actual feed rate shown in machine control is slower or it pauses as the machine enters and exits the tangent points as it should using G642. Since the water jet stream behaves differently than a solid cutter, this variation in the feed rate causes the cutting width (kerf) towiden when thefeederate isslow. The dwell marks are more visible the greater the B and/or C rotation angles.
Does anyone one know which settings to look at to eliminate/minimize acceleration-deceleration to prevent these dwell marks at tangencies?

Thanks in advance!