Machining allowance
| Symbol | q |
|---|---|
| Unit | mm |
| Attribute-ID | allowance |
| Numeric ID | 735 |
| Value Type | PMTechValue |
Specification of a machining allowance q causes the specified tool to be considered as the pre-machining tool, with which the root fillet is produced. The machining allowance q is relative to the upper deviation of tooth thickness Asne or deviation of base tangent length Awe of the finished flank. If no machining allowance is specified, the tool is considered as the finishing tool, with which the flank and the tooth root are produced.
The machining allowance q or a machining allowance with tolerance (q + qT) must be positive, and ideally should be specified if the gear is to be machined by two tools (pre-machining tool and finishing tool).
In the event that values are specified for both the machining allowance q of the gear as well as the machining allowance qWkz of the tool, these two values are added together for the calculation of the geometry.
| 1 | Nominal gearing |
| 2 | Preliminary gearing |
| 3 | Finished gearing |
| q | Machining allowance |
| qT | Machining allowance with tolerance |
| Awe | Upper deviation of base tangent length |
| Awi | Lower deviation of base tangent length |
Preliminary gearing
The machining allowance q is left on the flanks of the gear for the subsequent finishing.
Finished gearing
The flanks of the gear are finished corresponding to the upper tooth thickness.
Nominal gearing
Represents the allowance- and deviation-free gear; i.e. with ideal, precise, backlash-free flanks.
If only one tool is specified and a machining allowance is provided, the geometry is calculated as pre-machining In this case, the reasonableness of the resulting geometry and the plots created should be closely reviewed. Although the plot of the head track of the mating gear can be activated for pre-machining, it is not useful in this case.
The geometry can be completely determined using the following information:
- 1 tool without machining allowance q
- 2 tool with machining allowance q
For further information see STplus Chapter 4.2 (German)