With roots in the Bronze Age, turning is one of the oldest manufacturing processes. Wood, ivory and, since the Middle Ages, metal were used as materials. Precision mechanics and watchmakers used more advanced lathes from the 17th century onwards. In the course of industrialization, turning became a widespread technology. The basic principle has not changed to this day: A workpiece is set in rotation via a turning spindle and a cutting movement is generated by contact with a turning tool. The tool in turn makes a feed movement so that the workpiece is machined over a machine-dependent longitudinal path or the turning centres diameter. Modern CNC lathes far exceed this simple principle and are regarded as increasingly flexible precision wonders – from production turning to 6-sided complete machining.
CNC turning is undoubtedly one of the most flexible machining technologies. It starts with the variety of turning processes. In technical terms, a differentiation is made according to the characteristics and shape of the surface into face turning, round turning, screw turning (including thread turning), hob turning, profile turning and form turning. A further differentiation is made according to the position of the surface into external and internal turning, subdivided according to surface quality into roughing, finishing and fine turning. Above all, the advancing possibilities of NC controls and programming technology have ensured that turning machines are becoming even more versatile.
Universal turning, 6-sided complete machining and process integration
Turning is still by far the most efficient technology for machining rotationally symmetrical components. The combination of speeds of several thousand revolutions per minute and precision tools with long tool life ensures maximum efficiency and extremely precise production. Continuous further development has made lathes even more productive. Turrets or linear carriers for holding several tools, driven tools, a Y-axis for off-center machining and a counter spindle are now often standard features of a modern turning center. If required, a tailstock supports the machining of long workpieces. This equipment enables the production of complex turned parts in one work area, which in many cases makes the use of additional milling machines superfluous.
The integration of milling was the beginning of an evolutionary stage that continues to this day – 6-sided complete machining on turn & mill centers. Powerful turn & mill spindles that can rotate around the B-axis bring 5-axis simultaneous machining to the level of modern cnc milling machines in the work area of lathes. The machine also turns the back of a workpiece on a counter spindle so that a finished workpiece can be removed. Process integration goes even further at this point. With the help of innovative technology cycles, such as those offered by DMG MORI, gearing can also be produced or grinding processes carried out. In-process measurement completes the integration of additional process steps. In this way, tolerances are checked throughout and the effort involved in final quality control is minimized.
Machining Transformation (MX) with turning technology
Against the backdrop of rapid industrial change, innovative CNC turning machines and turn & mill centers are making a decisive contribution on the path towards the production of the future. They form a perfect basis for process integration, one of the four pillars of Machining Transformation (MX) – an approach with which DMG MORI enables companies to work competitively in the long term. The increasing integration of processes results in more efficient production. The advantages of complete machining in particular are obvious: it reduces throughput times to a minimum while freeing up capacity on other machines. This creates more flexibility in order planning. At the same time, the workload on personnel is also reduced, giving skilled workers more time for demanding tasks in work preparation or quality control. In addition, finishing in one work area benefits component quality because manual reclamping is a thing of the past.
Lathes for every application and every component size
With over 150 years of experience in turning, DMG MORI has comprehensive know-how that is reflected in around 20 series of different CNC lathes: From versatile universal lathes to innovative turn & mill centers to highly economical production turning, a wide range of applications is covered. The portfolio includes affordable turret lathes as well as flexible universal lathes with direct-drive tools, counter spindles or tailstocks. Where universal CNC turning machines like the NLX, CTX and CLX models reach their limits, DMG MORI's turn & mill centers are just getting started. Machines such as the CLX 450 TC or the models of the CTX beta TC and CTX gamma TC series as well as the NTX machines are used wherever demanding workpieces need to be turned and milled effectively and efficiently. The production lathes from the SPRINT series or the NZ platform, for example, demonstrate their strengths in series production in particular. The wide-ranging portfolio offers solutions for machining everything from the smallest workpieces to large components with diameters of over ø 1,000 mm and lengths of more than 6,000 mm.
Optimum capacity utilization through automated turning
Automated production on lathes has been an issue since the 1960s, initially using bar feeders. Here, the raw material is fed automatically through the turning spindle. The possibilities of manufacturing turned parts autonomously have developed enormously since then. For DMG MORI, this topic is another pillar of Machining Transformation (MX). This is why the machine tool manufacturer gives its turning machines, turn & mill centers and production lathes additional productivity with integrated automation solutions. These range from bar feeders and integrated robots for automatic workpiece removal to gantry loaders and a series of flexible robot applications for autonomous loading and unloading. These include the Robo2Go models, the MATRIS Light and the IMTR. Automation is a profitable building block for remaining competitive on the global market in the long term.
Competitive and sustainable through innovative turning
Thanks to their enormous versatility, CNC turning is increasingly becoming the backbone of efficient production. By finishing highly complex workpieces, they prove on a daily basis that productivity and precision can go hand in hand. Lathes are therefore of central importance for companies in the machining industry. On the one hand, they ensure a long-term competitive position on the market thanks to their versatility and performance. On the other hand, they enable resource-saving production that is in line with the increasingly important aspects of sustainability.
Important questions about CNC turning
What is turning?
The DIN (German Industrial Standard) defines turning as “cutting with a closed, usually circular cutting movement and any feed movement transverse to the cutting direction”. The axis of rotation of the cutting movement is fixed to the workpiece. This means that it retains its position in relation to the workpiece regardless of the feed movement. The aim of turning is to produce the workpiece in its geometric shape and dimensions precisely and in accordance with the technical drawings. The shape of the workpiece is determined by the geometry of the tool and the relative movements between the workpiece and the tool, known as the working pair.
What happens during turning?
A turning spindle causes a workpiece to rotate. Contact with a turning tool generates a cutting movement. The tool in turn makes a feed movement so that the workpiece is machined over a machine-dependent longitudinal path or the turning diameter.
How is a lathe constructed?
Lathes have a turning spindle that rotates the workpiece and turning tools that machine the workpiece. A turret provides space for several tools, which are guided to the workpiece as required. Alternatively, or additionally, turn & mill centers have a turn & mill spindle that changes tools from an external tool magazine in order to also perform milling operations. In advanced CNC turning centers, a counter spindle also allows workpieces to be machined from the rear.
What types of lathes are there?
The spectrum of lathes ranges from universal lathes to turn & mill centers for 6-sided complete machining. With the help of driven tools, many universal lathes also perform milling operations. Multi-spindle production lathes are also designed for highly efficient turning of large series.
What movements are involved in turning?
The relative movements in machining generally consist of a cutting movement and one or more feed movements. In turning, the workpiece usually performs the rotary cutting movement and the tool performs the necessary feed and infeed movements. The resulting movement from the cutting and feed movements is called the effective movement. The main cutting movement takes place during turning.