Innovative machine solution for run production: Spherical Parts in Shortest Cycle Times


The new SpheroStar by Thielenhaus Microfinish makes it possible to ma-chine spherical workpieces in short cycle times efficiently and with great pre-cision.

Based on the high-precision Sphero machine tool, Thielenhaus Microfinish has developed a highly efficient two-step solution which performs the entire fine-finishing process for spherical workpieces in short cycle times. The new SpheroStar is based upon the MicroStar and NanoStar platforms and like these two it is equipped with an indexing table.

The SpheroStar has two tool spindle slides that can automatically rotate to 90 degrees so that the optimal machining position for the chosen process is set up automatically or by the push of a button, thus enabling the production of flat surfaces as well – with optional cross slides – instead of only spherical surfaces. The units are mounted vertically and are easily accessible for fast changeover. The machine is loaded at the first station by a handling robot parallel to the machining cycle and later again unloaded while the other stations are machining. The indexing table then moves to station 2 where the workpiece is aligned axially. Pre-finishing is in-process gauging controlled in station 3 under size-controlled conditions, and the end-finishing with a flexible stone is done in station 4. This operation is in-process gauging controlled too. A MicroSens force sensor is used for both work steps with workpiece contact detection and stone wear compensation.

The SpheroStar has two tool spindle units that can automatically rotate by up to 90 degrees so that the optimal machining position for the relevant process is always easily achieved.
                                                                                            Photos: Thielenhaus Technologies GmbH

The clamped workpiece rotates at up to 4,500 revolutions per minute during machining. The spherical surface is created using a defined process and specially preformed finishing tools. Depending on pre-machining, the cycle time is only 12 to 13 seconds, so that the machine can be properly integrated into efficient production lines.

Since the main assemblies are from proven platforms that have already been on the market for years, the new machine also features the same reliability as other machines of Thielenhaus. For example the indexing table comes from Nano-Star, the swing slide and tool spindle from Sphero and the clamping and main spindle are from MicroStar.

This new SpheroStar enables machining of surface topography, spherical roundness, spherical diameter and sealing surfaces. Furthermore, it can be used to improve the contact ratio and to meet tribological requirements. In just a few installation steps that take only a very short time, the operator can convert the machine from outer machining to inner machining, i.e., from a ball valve to a sealing ring or a socket. Since the workpiece remains in the collet chuck until it is completely finished, the operator interference is reduced and clamping errors are ruled out. This increases process repeatability considerably.

Workpieces can be machined up to a diameter of 75 mm on the ergonomically designed machine. It is typically used for machining the axial piston pumps found in all fields of hydraulics. The axial piston has a spherical sliding surface at the end, and the dimensions of this component must be accurate to 1 µm or less in order to guarantee safe operation at great strain – such as in aviation. Another instance are the metallically-sealing valve balls and seating rings for valves in the chemical industry, through which aggressive or very hot media travel. These workpieces can be machined with a high degree of geometric and surface accuracy. Furthermore, the new SpheroStar is used in the automotive industry for machining the joint heads of wheel suspension and steering components that require a high level of freedom and movement for the associated assembly units.

More information can be found at: Thielenhaus Technologies GmbH, P.O.B. 201855, 42218 Wuppertal / Germany, Telephone + 49 (0)2 02 481-0, Fax + 49 (0)2 02 45 04 45, or on the Internet at