Small alterations to the involute tooth profiles are often made to avoid extreme changing tooth loads which can increase locally, at the mesh. The use of the tiprelief will cause less noise during meshing. Other form changes can absorb alignment errors during mounting and guarantee favorable tooth loads.
1 Tiprelief correction
2 Barreling and end relief
The barreling and the end relief are tooth shape corrections in axial sense. At the barreling the tooth thickness reduces slightly from the middle of the tooth to the sides according to a convex profile.
At alignment errors the load remains roughly in the middle of the tooth and one avoids lateral tooth forces, there where the tooth can capture less load. Barreling also allows greater alignment errors when mounting with a retention of a central tooth load.
The end relief is the replacement of the tooth thickness over a part of the facewidth on both tooth sides. It has a similar effect as the barelling but is easier to process and is therefore only an approximation of the barelling. It is thereby less effective than the barreling.
3 Tooth tip barreling
4 Tipchamfering en deburring
Tipchamfering of the tooth is carried out at the same time as the hobbing. The advantage of this is that the outer diameter is perfectly centrically with the pitch circle. This avoids cylindrical grinding of the tip diameter.
The deburring of the tooth tip is also carried out at the same with tooth milling using the same hob. Above figure on the left shows the hob profile (top) and the milled tooth profile (below). The advantage of this is that there is no chips left at the sides. However, the size of the tipchamfering is limited, because it directly affects the coefficient of contact. The dimensions can be found in the right figure.