cnc training in chennai

Some limitations of CNC controlled machinesr
Depending on their age and sophistication, CNC machines can be limited to the capabilities of their control and drive systems. Most CNC controllers only understand straight line movements and circular arcs. In many machines, the arcs are restricted to the principal XYZ planes as well. Rotary axis movements can be considered like linear movements, just degrees instead of distance. To create arc movements or linear movements that are at an angle cnc training in chennai to the principal axes, two or more axes must interpolate (move precisely in a synchronized manner) together. Linear and rotary axes can also interpolate simultaneously. In the case of five axis machines, all five must be perfectly synchronized – no easy task.

The speed at which the machine controller can receive and process the incoming data, transmit commands to the drive system, and monitor the machine’s speed and position is critical. Older and less expensive machines are obviously less capable in this, much in the same way that an older computer will work less well and more slowly (if at all) on demanding tasks than a newer one.

Interpret your 3D and spline data firstr
A typical problem is how to set up your files and do your CAM programming so that the machine executing your parts will work smoothly and efficiently with the data. Since most CNC controls only understand arcs and lines, any form that is not describable with these entities needs to be converted into cnc training in chennai something usable. Typical things that need converting are splines, i.e. general NURBS curves that are not arcs or lines, and 3D surfaces. Some desktop machine systems are not able to understand circular arcs either, so everything must be converted into polylines.

Splines can be broken up into a series of line segments, a series of tangent arcs, or a combination of both. You can imagine the first option as a series of chords on your spline, touching the spline on each end and having a certain deviation in the middle. Another way is to convert your spline into a polyline. The fewer segments you use, the coarser the approximation will be, and the more faceted the result. Going finer increases the smoothness of cnc training in chennai the approximation, but also dramatically increases the number of segments. You can imagine that a series of arcs might be able to approximate your spline within tolerance with fewer, longer pieces. This is the main reason for preferring arc conversion over simple polyline conversion, especially if you are working with older machines. With newer ones, there is less of a problem.

Imagine surfaces as the same kind of spline approximation, just multiplied many times in the across direction with a space between (usually called the stepover). In general, surfaces are done using all line segments, but there are situations where arcs or a combination of lines and arcs can also be used.

The size and number of segments are determined by the accuracy required and the method chosen, and will directly influence the execution. Too many short segments will choke some older machines, and too few will make a faceted part. The CAM system is usually where this approximation is done. With a skilled operator who knows what the user needs and the machine can handle, it is usually no problem. But some CAM systems may not handle splines or certain cnc training in chennai types of surfaces, so you might need to convert the entities in the CAD software first (Rhino) before going into CAM. The translation process from CAD to CAM (via a neutral format such as IGES, DXF, etc.) may also occasionally cause problems, depending on the quality of the import/export functions of the programs.

Common conventions used in describing CNC proceduresr
Your project can be:

2 Axis if all the cutting takes place in the same plane. In this case, the cutter does not have any capability of movement in the Z (vertical) plane. In general the X and Y axes can interpolate together simultaneously to create angled lines and circular arcs.

2.5 Axis if all the cutting takes place entirely in planes parallel to the principal plane but not necessarily at the same height or depth. In this case, the cutter can move in the Z (vertical) plane to change levels, but not simultaneously with the X,Y movements. An exception might be that the cutter can interpolate helically, that is, do a circle in X,Y while moving simultaneously in Z to form a helix (for example in thread milling).

A subset of the above is that the machine can interpolate any 2 axes together simultaneously, but not 3. This does make a limited number of 3D objects possible, by cutting in the XZ or YZ planes, for example, but is much more limited than full 3 axis interpolation.
3 Axis if your cutting requires simultaneous controlled movement of the X,Y,Z axes, which most free-form surfaces require.

4 axis if it includes the above plus 1 rotary axis movement. There are two possibilities: 4 axis simultaneous interpolation (also known as true 4th axis). Or just 4th axis positioning, where the 4th axis can reposition the part between 3 axis operations, but does not actually move during the machining.

5 axis if it includes the above plus 2 rotary axis movements. Besides true 5 axis machining (5 axes moving simultaneously while machining), you also often have 3 plus 2 or 3 axis machining + 2 separate axes positioning only, as well as in rarer cases 4 plus 1 or continuous 4 axis machining + a single 5th axis positioning only. Complicated, isn't it…

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