Production problems encountered by conventional tapping - such as the use of materials which are very difficult to machine, tapping blind holes with special machining requirements, i.e. flat-bottom holes, or untimely breakage - can now be easily overcome by the thread milling cutting method by interpolating axes Y2 and Z1.
Besides coping with the above, this method also results in a far longer tool life and, in spite of a succession of operations, production times are quicker than with conventional tapping.
The condition required for successful tapping is a lathe capable of interpolating axes X, Y and Z. The TB-DECO fitted to the DECO 2000 is able to interpolate all axes simultaneously and in a way which the user can parameterize fully. Consequently, an operation like the one described below, can be carried out with very simple programming!
Cross M3 tapping executed as follows:
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In order to machine the above part, a thread milling cutter with a 2.1 mm diameter and pitch of 0.5 mm is used.
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Description of the movement seen from above:
Milling takes place in 5 stages:
| Figure 1: |
STARTING POSITION OF THE MILLING CUTTER AT THE CENTRE OF THE HOLE |
| Figure 2: |
APPROACH TO 3mm EXTERNAL THREADCUTTING DIA |
| Figure 3: |
MILLING 1/2 CIRCUMFERENCE OF AXES Z1/Y2 AND MOVING X2 BY 1/2 THREAD |
| Figure 4: |
MILLING 1/2 CIRCUMFERENCE OF AXES Z1/Y2 AND MOVING X2 BY 1/2 THREAD, RETURN TO POINT OF APPROACH |
| Figure 5: |
REMOVAL OF MATERIAL FROM MILLING CUTTER, END OF MILLING |
Technical data:
Milling speed: 3200 rpm
Machined material: 9SMnPb28 steel
| d |
= |
milling cutter dia. 2.10 mm |
| d1 |
= |
drilling dia. 2.50 mm |
| d2 |
= |
external threadcutting dia. 3.00 mm |
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