Difference between Machining Centres and Turning Centres

Part programming for turning centres is very similar to that of machining centres as discussed earlier. However, there are a number of points to be considered that are specific to turning machines that need to be taken into account while programming for them.

Axes System

Because of the work rotation the 3D geometry of the part gets converted into 2D in the form of X and Z axes without the need for Y-axis. Majority of the turning centres are 2 axes only. However, there are some machines that have additional axes such as C, U, W and Y that require specialized programming.

Cut Planning

As seen earlier, programming of machining centres the tool path is generally offset from the original part contour by an amount equal to the cutter radius or the finishing allowance. That is relatively easy compared to the turning centres where

a large number of tool cuts have to be planned to remove bulk of the material. Some examples are shown later.

More than One Tool Post

 The turning centres generally have one tool turret which is relatively simple to program. However, there are many turning centres that have more than one tool post which has to be taken care while programming. For example in the case of a turning centre with two tool turrets, one turret may have X and Z axes while the other will have U and W axes.

Tool Nose Radius

Where as in machining centre, the programming is done with the centre of spindle and its top end, in turning centres, the programming is to be done with the centre of the tool nose radius, and compensation for the tool nose radius has to be done while programming.

Tool Indexing

Tool change in turning centre by means of turret indexing, though some turning centre have tool magazines in the traditional sense. As a result, the tool change position could be very close to the workpiece surface itself with enough clearance for the longest tool present in the turret.

Diameter Programming

The dimensioning practice used in lathe components requires that programming in X-axis for turning centre should have some kind of variation compared to machining centre programming. The tool in turning approach readily and making a provision for diameter programming helps in directly transferring the dimensions from the drawing directly without any change.