Position Behavior When Working With Q379 - HEIDENHAIN TNC 640 User Manual

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Position behavior when working with Q379

Several aspects must be observed when working with very long
drilling tools, e.g. single-lip deep hole drills or extra-long twist drills.
The position at which the spindle is switched on is decisive. With
extra-long drills, tool breakage may occur if the tool is not guided.
For this reason it is recommended to use the parameter STARTING
POINT Q379. This parameter enables you to influence the position
at which the TNC activates the spindle.
Start of drilling
The parameter STARTING POINT Q379 takes into account SURFACE
COORDINATE Q203 and the parameter SET-UP CLEARANCE Q200.
The following example demonstrates the relationship between the
parameters and how the start position is calculated:
STARTING POINT Q379=0
The TNC activates the spindle to SET-UP CLEARANCE Q200 via
SURFACE COORDINATE Q203.
STARTING POINT Q379>0
The start of drilling is at a specific value above the deepened
starting point Q379. This value is calculated as follows:
0.2 x Q379 If the result of this calculation is greater than Q200
the value is always Q200.
Example:
SURFACE COORDINATE Q203 =0
SET-UP CLEARANCE Q200 =2
STARTING POINT Q379 =2
The start of drilling is calculated as follows:
0.2 x Q379=0.2*2=0.4; start of drilling is 0.4 mm/inch above the
deepened starting point. Thus if the deepened starting point is
at -2 the TNC initiates the drilling process at -1.6 mm.
The following table shows various examples for calculating the
start of drilling:
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Fixed Cycles: Drilling | UNIVERSAL PECKING (Cycle 205, DIN/ISO: G205)
HEIDENHAIN | User's manual for cycle programming | 10/2017