Superfinishing for all batch sizes

Today, there is a broad mix of battery-electric, hybrid and pure combustion engines in motor vehicles. It remains to be seen where the journey will take us in terms of drive types. What has been apparent for some time, however, is that automotive OEMs are investing less and less in production facilities for combustion engine powertrain components, outsourcing their production to their suppliers. A similar picture can be seen with electric powertrain components, for which the quantities are comparatively low.

As a result, many suppliers are faced with an ever-increasing variety of parts with smaller batch sizes and fluctuating call-off figures. If the tribological properties of plain bearing seats, cams or the micro-geometry of rolling bearing seats require a superfinishing process (lapping, short-stroke honing) for these workpieces, it often becomes a challenge to be able to offer them economically or competitively.

One established option is to equip existing turning or grinding machines with attachments. These finish the required machining points after the actual turning or grinding process relatively inexpensively with a belt, stone or cup wheel for face machining.

However, the ambient conditions in the carrier machines are often not ideal for a superfinishing process. The very fine surfaces should not be used for parts handling, or workpiece trays and grippers must be equipped with soft, clean gripping surfaces. In addition, short-stroke honing often requires a honing or low-viscosity grinding oil to flush the tool. In addition to these technical aspects, the additional production step in the machine also increases its cycle time, which often results in the need to purchase a separate finishing machine.

The Supfina LCM superfinishing machine is a flexible solution for numerous superfinishing applications. © Supfina Grieshaber

Supfina offers the LCM series machines for these and other applications. The concept consists of a carrier machine that is equipped with the number and type of superfinishing attachments required for the respective processing task. This allows the superfinishing process to be implemented in a line cycle and in an environment that is optimal for the process. Another not insignificant aspect of this solution is that the machine supplier also assumes responsibility for the process, cycle time and workpiece quality. When using individual attachments, on the other hand, it should be borne in mind that with the constellation of carrier machine, attachment and user, the responsibility for bringing the attachment, carrier machine and process together and getting them running safely usually lies ultimately with the user.

The machines in the LCM series can be assembled relatively flexibly according to the modular principle and thus configured ideally for the respective processing tasks and workpieces. On the process side, these attachments offer the choice between machining with a superfinishing belt, finishing stone or cup wheel. The superfinishing belt is primarily suitable for the superfinishing of bearings, while a superfinishing stone is also suitable if the requirements for waviness in the circumference or cylindricity are very high. For finishing cams, on the other hand, the superfinishing belt is the tool of choice due to the complex cam profiles and attachments developed precisely for this process. Flat surfaces, on the other hand, can be finished with all three tools. With regard to the Supfina LCM, the options for customization and flexibility go even further. The workpiece can be held between centers as well as centerless in the roller mill or chuck, whereby the machines are available with spindle and tailstock in center widths of up to 800 or 1,500 mm. The spindle and optional tailstock position can be adjusted under NC control on request. When loading the machine, the user has almost every option available, from manual loading, optionally with automatic door drive, to loading hatches for robots or gantry loaders and an integrated gantry loader.

If we come back to the challenge mentioned at the beginning of having to finish different workpieces in small or medium batch sizes, the options that make setting up the machine faster and more error-free are particularly important. In addition to the automatic center width adjustment, Supfina's established quick-change systems for workpiece holders and tools also play an important role here. Equipping the LCM with one or more NC slides makes it possible to stitch several processing points with one device using a processing program or to automatically move to different positions depending on the workpiece type. Solutions for holding one or more attachments on the same slide or with individual NC slides for each individual device complete the design scope. All in all, component manufacturers have good opportunities to operate successfully on the market with highly flexible and economical production systems.