Walter combination tool saves machining time

In order to achieve a more efficient bearing sleeve machining, precision turning part maker Schuhmacher considered a composite cutter solution using two non-standard tools instead of six standard turning tools. Walter, a tool specialist based in Tübingen, offers this comprehensive solution.

Complex parts often involve many related factors, requiring multiple technical tools and the use of multiple tools to reduce production time. The more individual processes that are used, the greater the possibilities for optimization. In short, usually a few minutes of processing time can be saved.

For simple part processing that involves only a few processes, the optimization is more difficult. In this case, Ratio experts always try to save a few seconds: especially when the parts are being processed. However, it is precisely this type of part that sustains the daily livelihoods of many engineers SMEs: turned parts such as pins, bushings and various types of shafts. This also applies to the Schuhmacher company in Germany. The company designs and produces about 1800 complex turning workpieces of different materials each year. Some materials require additional processing, while others are completely assembled. The order list also includes a bearing sleeve made of 16MnCr5 with a diameter of 51mm and a length of 65mm; the order quantity is 200,000 per year. Due to the huge price pressure, Schuhmacher was forced to reduce the casing processing time from 58s to 45s.

The bearing sleeve in the example is a cylindrical bearing sleeve. These parts are difficult to machine. In this example, the overall length, the roundness of the inner diameter, and the parallelism of the two end faces have a tolerance of 0.02 mm, and a wall thickness of a few millimeters. Inner diameter machining becomes a tricky job. The clamping force of the clamping system must be appropriately reduced, otherwise the sleeve may be deformed. This means that the realization of processing reliability allows only relatively small cutting forces to exist. In this case, the increase is very limited for larger cutting depths and high-speed cutting parameters aimed at reducing the running time.

With regard to the Takamaz X200 two-axis lathe and its peripheral equipment, Schuhmacher has developed a global and consistent solution: The use of a bar feeder to feed the raw material into the clamping system. After processing, the handling system transports the casing to the robot. Initially, the manipulator transferred the machined parts to the cleaning station, then to the measuring station for full automatic 100% measurement, and finally placed the formed casing on the pallet.

Up to now, six tools are still needed to perform single machining processes such as face machining, internal turning and chamfering. Three tools are used for the spindle operation and three are used for the subspindle operation. The machine will divide the bar before moving to the counterspindle. The only need to optimize is the face processing and chamfering process. Due to the thin casing wall, there is almost no optimization requirement for the splitting operation, so this is ignored and the purpose is to reconfigure the machine tool.

Tool design on the machine

How to save the required processing time according to the part processing cycle and the corresponding production environment? This is a question raised by the manufacturer of precision turned parts to the tool supplier Walter. Walter has provided tools for parts other than the bearing housing. The managing director Mr. Dominik Schuhmacher explained their requirements: “We told Walter. This is our part. It is our lathe and processing technology. Please think about it and tell us how to satisfy the customer's needs.”

The first step is to perform a basic analysis of the parts, lathes, and machining processes involved. Mr. Marc Etter, technical consultant and sales manager of Walter AG in Germany, said: “We realize that only a completely new tool concept can help us achieve the desired goal.” As an experienced application engineer, Mr. Etter plans to replace the standard with a combined tool. Tool. Together with Thomas Haller, manager of Schumacher's CNC department, he designed two combined tools, one for spindle operation (with four blades) and the other for secondary spindle operation (with three blades). In order to shorten the total processing time as desired, two major factors need to be considered, namely the elimination of tool change and the shortest possible stroke.

Mr. MarcEtter said: "The design of non-standard tools used in machine tools is not something we need to do every day, but it is very effective. Usually, the staff design in the design room rather than the machine." Mr. Thomas Haller added: "Of course We are very happy to provide unconventional practical support." The design of the two processing specialists was submitted to the design shop of the tool manufacturer in Tübingen and from there was transferred to the tool manufacturing shop.

After using the blade for fine-tuning, the result is better than expected: the combined tool only needs 38s. All in all, this means that the machining time per bearing sleeve can be reduced by 20 s. Based on this, we can save more than 1,100 hours in this area in more than a year. Only a small amount of fine tuning is needed because of Tiger. The tecWPP20 inserts have improved cutting parameters. Mr. MarcEtter explained: “When selecting the material for inserts and cutting tools, we must consider several factors, especially strict concentricity and radial run-out tolerances, as well as the cutting force limitations resulting from lower clamping forces. We have chosen The blade made of WPP20 has a total of 4 different groove shapes (depending on the individual processing technology), which can form a better chip flow direction and meet the packaging requirements in an optimal way."

Walter offers two types of combined tools using the Monoblock-based DINISO insert seat and the Walter Capto interface. Introducing this interface on a twin axis machine is an innovation. The standard VDI turret is equipped with a suitable adapter for the installation of tools. With the Walter Capto quick-change interface, users can significantly reduce downtime due to wear.

Mr. Dominik Schuhmacher concludes: “We assume that the company will use more such tool combinations. If the number is large, then such a solution will be successful for a foreseeable period.”