Traditionally, one of the largest barriers to achieving high surface finish has been vibration. Considering the whole spindle system, vibrations can be induced by several different components. Whether looking at the concentricity quality and balancing of the tool, toolholder system type, spindle interface or interface diameter, there is an intrinsic vibration existing within the system itself. Part clamping, pallet systems and the geometry of the mold being machined also can influence vibration.

Additionally, there are real-time vibrations generated by the milling process itself—placing considerable radial forces on the spindle system and adversely affecting the ability to maintain high surface finishes.

While intrinsic vibrations can be minimized through the proper selection and balancing of tools and toolholders, the vibration generated by the cutting process itself varies largely by application. Fortunately, tools now exist to help moldmakers analyze and eliminate this variable.

Through combinations of software and hardware, today’s moldmakers have an unprecedented ability to precisely monitor levels of vibration throughout the machining of a mold. For example, some machine spindles1 contain a built-in radial acceleration sensor called an Advanced Process System. In combination with software installed on the machine, this allows the generation of a graphical representation of vibration. Systems such as this provide tremendous value.

On a series of identical workpieces, vibration data monitoring can be used to optimize the process and make it more reliable. By using this information, machine operators can fine tune the machining process and define the maximum levels of vibration allowable to maintain the needed surface finish. These levels of deviation can be programmed into the software so that the machine generates a warning or shuts down if they are exceeded.

Whenever variables arise that begin to cause levels of vibration that will result in unacceptable surface finishes, the operator receives instant notification. This helps optimize performance and allows the machine to run at its maximum productivity, while guaranteeing the surface finish quality required by the mold.