Mechanical Joining

The Nature of Mechanical Joining

Mechanical joining: connection through form and force closure

There is currently a growing trend towards the development of mechanical joining processes, which has been created by the increase in intelligent lightweight construction with its tendency to combine different materials. This kind of joining technology is characterized by a forming process that involves the mechanical interlocking of materials. For this purpose, the flow of the materials and the joining element is influenced during the joining process in such a way that form and force closure between the combined materials or the additional joining element are achieved. Mechanical joining is the most economical way to manufacture multi-material products.

App. Clinching: Tool and materials (Source: Eckold)
Clinching: Tool and materials (Source: Eckold)
Clinching: cross section of characteristic mechanical interlocking between the materials (Source: Eckold)
Clinching: cross section of characteristic mechanical interlocking between the materials (Source: Eckold)

Mechanical joining: Typical Industries and Applications

Typical fields of application for mechanical joining are:

  • Automotive industry (car body, seat rail, hood, sliding-roof frames, window regulators)
  • Aerospace industry (outer shell assembly)
  • Ship, yacht and boat building industry (hull assembly)
  • White goods industry (housing construction, drawer rails)
  • Air-conditioning and ventilation sector (segment assembly)
  • Renewable energies (Wind turbines and solar power modules)
  • Medical technology (active wheelchairs, implants, medical equipment)
  • Steel and plant construction (facades, bridges, towers – for example the construction of the Eiffel Tower in Paris used 2.5 million rivets)

Trends and Developments

Where is mechanical joining heading and what will the future bring?

The trend towards intelligent lightweight construction means that every element of a product must be made of the best materials in terms of function, durability, production and cost. As a result, multi-material composition is increasingly common. The assembly of multi-material elements is the biggest challenge in multi-material design is the biggest driver of costs, and therefore provides the most opportunities for innovation.

To exploit the potential of lightweight construction for a more efficient element design, many industries, especially the automotive and aerospace industries, increasingly use fiber-reinforced plastics, aluminum, cast materials, high strength steels, and metal foams. To safely combine these different materials and form so-called multi-material modules, intensive work on the development of new joining methods and the optimization of existing mechanical joining technologies is currently underway.

Typical Challenges

Primary Considerations

App. Typical defects in self-pierce riveting
Typical defects in self-pierce riveting

Process parameters which must be considered to help adjust the joining technology to the materials, their thicknesses, arrangement, and accessibility include:

  • Choice of appropriate joining technique
  • Choice of appropriate process variants
    • Adjustment of joining elements in relation to dies or tools
    • Punch force, blank holder force
  • Systematic consideration of variations in material thickness, material strength, lubrication improves robustness
  • Understanding die loads and die life leads to reductions in down-time
  • Reduced damage (joining elements, material) during joining process (results in reduction in reworking)
  • Resistance of connections to static and dynamic loads
  • Influence of adhesives on the connection formation
  • Influence of material strain-hardening on the connection formation
  • Understand influence of C-frame spring-back and eccentricity
  • Development of new joining technologies

 

Multi Point Considerations

Self-piercing rivets in an automotive application

Multi-point inspections, meaning interdependency between joining points

Sequential arrangement to minimize assembly distortion

  • Minimize joining point distance
  • Span the virtual process chain of car body components: manufacturing of the joining elements – to mechanical joining – to the crash simulation

Our Solution for Mechanical Joining

Mechanical Joining Module in Simufact Forming

The module Mechanical Joining was designed specifically for the simulation of mechanical joining processes. It allows for the numerical computation of technologies primarily based on joining-based forming. Therefore, various riveting procedures, such as punch riveting, self-piercing riveting or blind riveting, can be analyzed. It is also possible to simulate the connection formation in diverse joining by shearing and upsetting or clinching technologies with a fixed or an opening die. Furthermore, special effects such as high joining speed (e.g., when setting bolts) or a high momentum (e.g. flow-drill screws) can be taken into account. An analysis of adhesives in the joining zone is also feasible.

Simufact Forming Mechanical Joining contains a library of CAD descriptions of your joining tools and elements and automatically calculates the specific connection parameters. Furthermore, this module offers a specially adjusted simulation set-up that ensures solution stability.

 

Take advantage of Simufact Forming for your mechanical joining processes

When your joining specialists perform robust and high-performance simulations with experimentally validated results, you are able to:

  • Predict the characteristic of joining parameters (e.g. interlock) with variable joining set-up and behavior under load
  • Evaluate the effect on robustness from deviations in material thickness, material properties, lubrication or press properties
  • Reduce expenses substantially  
    • Fewer experimental tests
    • Fewer cross-section preparations and connection parameter measurements
    • Lower resources (time, staff, presses) for experimental analysis and evaluations
  • Gain significant process expertise
    • Determine the behavior of rivets and materials during joining
    • Increase the stability of the joints and the process
    • Predict failure for tools or rivets

For a functional analysis of Simufact Forming Mechanical Joining, please read our product description.

Simufact Forming Mechanical Joining