Retaining

HOW TO: RETAINING


Learn how to secure bearings, bushes and cylindrical parts in housings or on shafts.


The aim is to achieve a maximum load transmission capability and uniform stress distribution while eliminating fretting corrosion.

Read more about:

Types of fits

Load transmission

Curing methods with liquid retaining products

Retaining: Additional Knowledge

Learn everything you need to know about the subject of retaining.

The most common positive-drive assembly is the conventional key/keyway system. Other positive drive assemblies involve the use of grub screws, pins and spline shafts.

They transmit torque levels commensurate with the degree of mechanical interlocking achieved.

These assemblies (except the spline shaft) have an uneven distribution of mass, an imbalance that can lead to vibration at high speeds. All positive drive assemblies allow micro-movements. This results in wear and tear (e.g. in the form of fretting corrosion), with the risk of development into macro-movement failures, particularly in dynamically loaded assemblies.

  • High stress concentration due to the "notch effect" that occures in the area of a key. Also permanent relative movements lead to abrasive wear of both parts e.g. key and shaft.
  • Uneven distribution of mass.

Well-known friction dirve assemblies include press fits, taper fits and shrink fits. These assemblies can be very economical; there is no imbalance at high speeds. They are capable of axial and torsional load transmission.

  • Restriction by material properties, surfaces roughness and design as these assemblies rely on friction/interference alone to transmit torque.
  • Very close tolerance needs result in high machining costs
  • Because of surface galling disassembly is often difficult or even impossible
  • High stress in components/operational loads can lead to part failure.

Welded, brazed or soldered assemblies are high in strength but have a relatively small joint area bearing in the entire load.

Retaining of cylindrical parts - Material integration with retaining.

•  Mating materials must be compatible

•  High process temperature can lead to possible distortion of parts

•  Heat can create residual stresses leading to structural degradation in joint area

•  Disassembly largely impossible

Material integration by using liquid retaining products can be achieved by bonding shaft/hub connections.

  • Higher performance with existing design & geometry solutions
  • Equal performance with improved design (smaller, lighter, ...)
  • Plus, LOCTITE anaerobic retaining compounds offer an additional retaining solution, the bonded slip fit.


Strength comparison (schematic)

All situations that can be improved by bonding.

Retaining of cylindrical parts - Liquid retaining strength comparison