TNC 640 with new features

By Abhilash Tripathi, Associate Director (Sales & Service), Heidenhain India

Since its market launch, the TNC 640 has increasingly been becoming the first choice for high-end controls with efficient and highly precise milling operations. Why? Because it makes milling so simple, because HEIDENHAIN has expanded its functions in a practical, user-friendly way with a keen sense of workshop needs, and because in addition to milling it also enables turning on the same machine.

The new features of software version 4 currently being dispatched for the TNC 640 range from the programming and simulation of operations directly on the machine to setup and configuration, as well as many machining functions. This makes milling even more simple, safe and precise. Operators also program for turning operations just as simply as for milling. The TNC 640 masters both forms of machining without complex switching over.

3-D simulation graphic with a host of benefits

The most extensive new feature is certainly unique, true-to-detail 3-D simulation graphic functionality. This helps the HEIDENHAIN TNC 640 operator to identify missing information or inconsistencies in the program prior to machining, and without any risks to workpieces, tools or machines. It displays the workpiece at random viewing angles and simulates both milling and turning operations in a single view. Not only cuboids are displayed but also cylindrical forms such as cylinders, tubes and rotationally symmetric blanks.

During simulation, several new view options expose a precise and freely selectable view of details. The graphic simulation is so detailed that the machine operator is able to identify undesired machining effects from NC programs, such as sub-standard surfaces, at an early stage. With maximum 3-D simulation resolution, the control can also display the block end points with corresponding block numbers in the display of tool motion as a 3-D line graphic. With externally created NC programs generated with CAM systems this facilitates the analysis of point distribution and pre-evaluation of the expected surface.

The operator can choose to view only the workpiece, only the tool paths or both simultaneously. Views also enable display of the original workpiece blank dimensions as a frame with highlighted main axes, or with the workpiece edges as lines for improved spatial perception. The “transparent workpiece” view option also enables a view of inside machining, even with rotationally symmetric workpieces. Color highlighting of the workpiece with a new color used for each new tool helps the operator to identify individual work steps and makes it easier to assign the tools used. The operator can also display the tools either completely or transparently and of course hide these at any time.

Several advantages are provided for the operator by 3-D simulation on the TNC control. For example, he can rapidly and simply run through machining programs created on the machine. But simulations on the control are also highly useful from programs he adopts from CAD/CAM systems, because the 3-D simulation graphic of the TNC 640 takes into account the kinematics model saved on the control, optimally modified according to the actual machine tool geometry, to realistically simulate machine movements.

Milling and turning in one setup

Does your workpiece, after complex milling operations, also have to be set up on a lathe for further machining? Here the TNC 640 helps you to save a great deal of time! A milling/turning machine equipped with the TNC 640 machines the workpiece in one run, combining milling and turning in any sequence. For this purpose, the control simply alternates between turning and milling mode according to the program and completely independent of the machine and axis configuration. During switchover, the TNC 640 assumes all necessary internal changes (such as switching to diameter display, or setting the datum in the center of the rotary table), as well as machine-dependent functions (such as clamping the tool spindles). In this way the TNC 640 not only saves space as well as money for an additional machine, but thanks to doing all operations on a single machine, it also avoids inaccuracies possibly caused by workpiece rechucking.

The operator can create turning contours as usual in the HEIDENHAIN plain-language dialog, and he also has contour elements such as recessing or thread undercutting as well as cycles for turning shoulders, recessing, contour machining and thread machining. He can also use FK free contour programming to easily create contour elements or simply import contours in DXF format with the help of the DXF converter. In more sophisticated contour turning cycles, the TNC 640 uses the same techniques as used for milling. Here, too, there is no need for the TNC programmer to learn new ways of programming he build on what he already knows and quickly find his way into the world of turning on a milling machine.

Another highlight of the TNC 640 is the blank form update feature. Based on the defined blank, the control calculates the newly created intermediate product with each step to adapt the following machining cycles accordingly. This avoids air cuts and optimizes approach paths.

Optimized motion control for clean surfaces and perfect contours

An insufficient quality of data in NC programs frequently causes an inferior surface quality of the milled workpieces. The Advanced Dynamic Prediction feature (ADP) expands the previous look-ahead of the permissible maximum feed rate profile, thereby enabling optimized motion control of the feed rate axes with 3-axis and 5-axis milling. In this way, clean surfaces can also be milled with short machining times on contours characterized by strong point distribution deviations in adjacent tool paths.

The control dynamically calculates the contour in advance and can therefore use acceleration-limited motion control with smoothed jerk to adapt the axis velocity at contour transitions in good time. ADP shows its strengths for example during bidirectional finish milling through symmetrical feed behavior on the forward and reverse paths as well as through particularly smooth feed rate curves on parallel milling paths.

Fine tuning with attention to detail

The TNC 640’s quickly understandable user interface ensures an even better overview during programming and setup. The individual screen areas are clearly distinguished and the operating modes are indicated by unambiguous symbols. Value inputs, comments and syntax elements are color-highlighted, and error messages are categorized with colors according to importance.

The latest software version 4 simplifies program creation and input of technology data on the TNC 640. With the context-sensitive cutting data calculator, the operator can calculate spindle speed and feed rate for the specific machining process and transfer these values directly into the open feed-rate or shaft-speed dialog. The calculator recognizes the open dialog window and automatically asks only for the required input data.

Face milling cycles, of course, have long been a part of the performance range of HEIDENHAIN TNC controls, although this does not mean that familiar features cannot be improved. For example, a new face milling cycle enables the definition of up to three sides for limiting face machining on side walls or shoulders. For corners between by adjacent sides, even the corner radii can be specified as desired. Faces can be milled with various machining strategies: meandering, line-by-line (with or without overrun) or helically. Operators can also specifically define the machining direction, for example for directing the operating pressure against the fixed vice jaw.

In addition to such expansions and optimizations, many other detailed improvements have also been integrated that are too extensive to describe here. The new software version 4 for the TNC 640 converts a wide range of customer requirements into workshop-oriented solutions.