| Symbol | νll |
|---|---|
| Unit | - |
| Attribute-ID | adhesion_coefficient_release_force_longitudinal |
| Numeric ID | 200241 |
| Value Type | PMDouble |
The coefficient of adhesion νr is the ratio of the measured sliding force to the calculated normal force in the joint. The coefficients of adhesion ν must be distinguished from the coefficients of friction (adhesive or sliding friction), where the calculated normal force is replaced by the measured normal force. The coefficients of adhesion are different when the release or sliding force acts in the longitudinal or circumferential direction.
The coefficients of adhesion vary depending on whether a transverse interference fit (joining by heating the hub and/or cooling the shaft) or a longitudinal interference fit (hub and shaft are pressed axially together) is involved.
The following table in accordance with DIN 7190-1 Section 5.3 provides safe adhesion coefficients when slipping for transverse interference fits in the longitudinal and circumferential directions.
| Material pairing, lubrication, joining | Coefficients of adhesion νru, νrl |
| Steel-steel combination | |
| Pressure oil fits normally joined with mineral oil | 0.12 |
| Pressure oil fits with degreased pressure surfaces joined with glycerine | 0.18 |
| Normal shrink fit after warming of the outer part up to 300°C in an electric furnace | 0.15 |
| Shrink fit with degreased pressure surfaces after warming of the outer part up to 300°C in an electric furnace | 0.20 |
| Steel-cast iron combination | |
| Pressure oil fits normally joined with mineral oil | 0.10 |
| Pressure oil dressings with degreased pressing surfaces | 0.16 |
| Additional steel combinations: | |
| Stel-MgAL combination, dry | 0.10 to 0.15 |
| Steel-CuZn combination, dry | 0.17 to 0.25 |
The following table according to DIN 7190-1 Section 5.2 gives adhesion coefficients for longitudinal interference fits in the longitudinal and circumferential directions during loosening and slipping.
| Materials | Coefficients of adhesion | |||||
| old | new | dry | lubricated | |||
| Number | νll | νrl | νll | νrl | ||
| St 60-2 | E 335 | 1.0060 | 0.11 | 0.08 | 0.08 | 0.07 |
| GS-60 | GE 300 | 1.0558 | 0.11 | 0.08 | 0.08 | 0.07 |
| RSt37-2 | S 235JRG2 | 1.0038 | 0.10 | 0.09 | 0.07 | 0.06 |
| GG-25 E | EN-GJL-250 | 0.6025 | 0.12 | 0.11 | 0.06 | 0.05 |
| GGG-60 | EN-GJS-600-3 | 0.7060 | 0.10 | 0.09 | 0.06 | 0.05 |
| G-AlSi12(Cu) | EN AB-44000 et. seq. | 0.07 | 0.06 | 0.05 | 0.04 | |
| G-CuPb10Sn (G-CuSn10Pb10) | CB495K | 2.1176.01 | 0.07 | 0.06 | – | – |
| TiAl6V4 | TiAl6V4 | 3.7165.10 | – | – | 0.05 | – |
| – Coefficients of adhesion unknown | ||||||
The values given in the table apply to continuous loading. They have been determined using internal parts made of the material X 210 Cr W12 (acc. DIN EN ISO 4957) and are valid for steel. After joining, the interference fits should settle for approx. 24 h before the first load is applied.