Technology Tips and Tricks

The PNC DECO control instantaneously corrects the offset value when it is called up whilst the programme sequence is being run on the machine. This is one reason why contour faults may occur. The difference between the offset values - in our case T12 and T52 - is immediately taken into account when a new offset is called up.
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Tips and Tricks

Tool offset concept

Compatibility :
DECO 7/10a  |   DECO 13a  |   DECO 13bi  |   DECO 20a/26a
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Machining the part below. Dia. 5 is machined using tool T12 which is associated with offset 12 and, to achieve greater flexibility you wish to use a second offset - e.g. T52 which is associated with offset 52 for an 8 mm diameter.

Figure 1/2
Figure 1 0 Figure 2


Depending on the values entered in the machine for offsets 12 and 52 for X and Z axes, the contour which has been programmed (Fig. 1) is not executed correctly. Errors (Figs. 3 to 6) appear. Why?

Figure 3/4
Figure 3 0 Figure 4


Figure 5/6
Figure 5 0 Figure 6


Explanation
In a conventional CNC, tool offset is directly taken into account when calculating the distance to be covered. However, the TB-DECO concept does not have a tool offset but only the tool geometries. Consequently, a link, which is defined by the operator, is carried out between the tool catalogue containing the geometries of each tool and the corresponding axis tables. The PNC DECO control instantaneously corrects the offset value when it is called up whilst the programme sequence is being run on the machine.

This is one reason why contour faults may occur. The difference between the offset values - in our case T12 and T52 - is immediately taken into account when a new offset is called up.

Solution
The link between tool geometry and locating the offset in the corresponding axis table is selected by default for all axes, but can be individually deactivated axis by axis using the form "Offset selection" of the "Tool edition" menu (see TB-DECO operating aid).

Figure 7
Figure 7 		Offset selection:
T..XYY
12333
523  
53  3


ISO Code:


G1 X1 = 5 Z1 = 0 T12
G1 Z1 = -10 F0.05
G1 X1 = 8 T52
G1 Z1 = -15 F0.07 T53 		When moving to segment 1, all axis offsets are active whilst, on the other hand, when the offset changes to segment 2, then only the offset for axle X is placed. This means that provided there is a difference between offset 12 and 52 on axle Z, there is no risk of a contour fault. If an offset is required for the length, for segment 3, then T53 is added.


Conclusion
If the machining process allows, it would be preferable to quit the part contour, activate the second offset outside the part material and then to re-integrate the part contour. Thus compensation for the difference between the two offsets takes place outside the part contour.

If the machining process requires you to remain in the contour, then the "offset selection" method indicated above can be used, so as to avoid any errors in the contour.

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