The push to modernize technology-intensive sectors in Asia—such as automotive, aerospace and general engineering—is constantly stretching machine tool builders in the region to their limits. The demand is not just for standard machines. At present, around half the orders from the eastern Asia region are for customized, special-purpose machines and projects—some of which are turnkey—adding to the complexity of what needs to be delivered.
As the demand for heavy-duty machining continues to increase, the difficulty for local producers to meet it is being bridged by importing high-quality machine tools.
One of those global sources of special-purpose machines, Weingärtner Maschinenbau, Kirchham, Austria, provides complete, customized, heavy-duty machining solutions for the energy and aerospace industries as well as the pump, plastics and recycling sectors. Its special-purpose machines manufacture crankshafts for diesel engines, rolls for the steel and paper industry, extruder screws for plastics production and shafts used in turbines and stationary generating units.
As a solution provider for heavy-duty machining, the Weingärtner portfolio includes customized machines and software, application-specific technology, consultancy and training, as well as global support. This approach is mirrored by its cutting tool technology partner, the Ceratizit Group, Kempten, Germany. Working together, Weingärtner and Ceratizit have collaborated on major projects since 2012 and have developed a solid working relationship.
The collaboration between the companies can be seen in a recent example of a complete machining solution for chilled iron rolls. The customer wanted to replace up to four conventional machines for roll production with a single one. It was initially envisaged that grinding operations would continue to be carried out on a separate machine.
One of the main challenges for the project lay in machining roll material, which is produced using the centrifugal casting method. The roll material has a hard outer shell and softer core. Hardness of the rolls varies from up to 85 ShC (Shore’s Sceleroscope) for the 50-90 mm thick outer shells to the softer core materials, with a hardness between 38 and 45 ShC.
Among the parts being machined on the journals are bearing seats and drive faces. This mixture of hard roll and soft journal material required the use of various cutting materials in Ceratizit’s tools, such as silicon nitride, mixed ceramic, carbide and CBN. Depending on the type of roll, the complete machining process encompassed a wide range of machining operations, including turning, grooving, milling, drilling, deep-hole drilling and thread cutting.
The machine concept chosen for the project was Weingärtner’s Multi Product Machining Center (MPMC). The MPMC series is designed for heavy-duty machining applications. The machines are horizontal turn-mill centers that can be used to machine components with diameters up to 2,000 mm, machining lengths up to 15 m and a maximum workpiece weight of 80 tons.
Equipped with a turn-mill head and fully automatic interchangeable machining units, machines in the MPMC series enable complex parts to be produced on a single machine in a cost-effective manner, according to Weingärtner. The type of machining application determines which of the boring, trochoidal, gear cutting or deep-hole drilling units is used. One of the features of the MPMC for roll machining is its two CNC-controlled workpiece loading aids and a CNC-controlled steady rest.
Another feature of the machine that has a direct impact on the tool design is the B axis, which enables the setting angle of the tools and the required cutting depth to be continually adapted to the current machining situation to achieve high feed and productivity figures. This advantage is driven home by the fact that the turning tools can be moved as required in both directions. The Y axis allows positioning the cutter over the tool axis, which significantly increases tool stability, according to the company.
The hardness of the work material, cutting depths of up to 20 mm, and the non-homogeneous nature of the material are a challenge for cutting tools used to machine the rolls. Ceratizit’s tooling package for machining chilled iron rolls includes turning, grooving and milling tools as well as systems for drilling, thread milling and tapping. The tools come from the company’s flagship brands: Cutting Solutions by Ceratizit, Komet, WNT and Klenk.
LNMR 50, SCMT 38 and SN 25 inserts, with cutting lengths of 50, 38 and 25 mm respectively, are available for users performing heavy-duty turning. For grooving, the HX system—with groove widths between 16 and 60 mm—is used so that the required contours can be produced on the journals, the shoulders or the individual rolls.
Key faces and bore radii are among the areas requiring milling around the journals. For these applications, AHDM series tools for heavy-duty cutting and AHFC tools for high-feed cutting are used, as well as MaxiMill A271 face mills and special radius milling cutters. Fitted with ten inserts, MaxiMill cutters offer high feed rates per tooth with shallow cutting depths, according to Ceratizit.
The company also employs VHM end mills and CBN-equipped finish milling cutters in finishing the key faces. For drilling applications, Ceratizit tools can machine diameters up to 155 mm and deep-hole drill up to 60×D. The range is divided into MaxiDrill MD900 indexable insert drills, which are used across the entire range of diameters from 12-63 mm, and solid-carbide tools for smaller holes. Threads down to M2 are also produced for workpieces weighing 18 tons.
After provisional acceptance by the customer, the Weingärtner MPMC for roll machining was dismantled and shipped to its destination, where the customer installed it with specialists from Weingärtner and Ceratizit before carrying out the final acceptance. Both companies agreed that a comprehensive, machining-oriented, and professional service offering is essential for regional markets, especially when it comes to follow-up on heavy-duty machining projects.