Once assembly is complete, the system undergoes functional testing. All systems must be tested, documented, and approved by the customer; only then is an industrial assembly project considered successfully completed. Commissioning is therefore the phase where the quality of the entire assembly work is revealed. A structured approach at this stage prevents technical defects, rework, and delayed production release.

Why commissioning determines project success

In industrial assembly, project success is often measured by assembly performance—that is, whether machines and components are set up on schedule. In reality, however, success is only determined during the commissioning of the systems. A machine that is mechanically perfect but does not produce reliably is worthless to the operator.

Errors that remain undetected during this phase manifest later during ongoing operation: through unplanned downtime, production quality issues, or damage to components. Furthermore, there is an economic impact, as every day between the end of assembly and production release costs money without the system creating value. A structured commissioning process shortens this exact phase.

The five-step commissioning process

Regardless of the industry or type of system, commissioning in industrial assembly follows a proven basic pattern. The individual steps build on one another and should not be skipped:

  • Verify mechanical completion: Before the first power-up, it is verified that all components have been assembled, aligned, and secured according to technical specifications. This also includes piping, cabling, and connection to utility supplies.
  • Cold commissioning: The system is tested without product and without load. Checks include rotation directions, limit switches, sensors, signal paths to the control system, and the functionality of all safety devices such as emergency stops and protective covers.
  • Hot commissioning: The system runs under real conditions for the first time, with utilities, materials, or product. Parameters are adjusted, processes are optimized, and the interaction of all systems is verified.
  • Trial run and performance verification: Over a defined period, the system must demonstrate that it consistently delivers the agreed-upon performance in terms of quantity and quality. This test run forms the basis for final acceptance.
  • Acceptance and handover: Functional tests are conducted and logged together with the customer. With documented acceptance, the system officially transitions into the operator's area of responsibility.

For many industrial assembly projects, on-site commissioning is preceded by factory acceptance tests. During a Factory Acceptance Test (FAT), the system is checked at the manufacturer's site, while a Site Acceptance Test (SAT) is performed after assembly at the final location. Both tests reduce the risk of fundamental defects being discovered too late.

Key inspection steps at a glance

Within these phases, specific inspection steps have become established in industrial assembly that should be part of almost every commissioning process:

  • Visual inspection and completeness check: Comparing the installed system against plans, drawings, and parts lists
  • Electrical installation check: Verifying connections, circuit protection, and signal paths between field devices and the control system
  • Functional testing of safety equipment: Testing emergency stops, interlocks, and protective devices in accordance with applicable standards and safety requirements
  • Mechanical and drive system inspection: Checking alignment, rotation directions, lubrication, and running performance
  • Control system parameterization: Setting and documenting all relevant process parameters
  • Functional testing in automatic mode: Running through all operating states, including fault scenarios and restart procedures

Each of these steps is recorded in writing. Test reports are not just a formality; they are the foundation for production approval and future warranty claims.

Common commissioning errors and how to avoid them

The typical risks involved in commissioning industrial systems have remained the same for years. The following overview shows the most frequent errors, their consequences, and the appropriate countermeasures:

Common Mistake Typical Consequence Prevention
Technical defects from installation remain undetected Malfunctions and damage during ongoing operation Carry out systematic inspections during installation, not only at the end
Incomplete documentation Delayed acceptance, problems with warranty claims and maintenance Maintain inspection reports and parameter lists continuously instead of creating them afterwards
Insufficient time allocated for testing Delayed production release under deadline pressure Plan commissioning as a separate project phase with realistic time reserves
Safety inspections are skipped Liability risks and danger to personnel Make safety tests a mandatory approval requirement before every trial run
Unclear responsibilities between different trades Additional rework and costs Assign one dedicated project manager to coordinate mechanical, electrical and control systems

A pattern emerges: most errors are not caused by a lack of expertise, but by time pressure and a lack of structure at the end of a project. This is exactly where an experienced industrial assembly partner pays off—one that plans commissioning as an integral part of project execution.

Documentation: The underestimated duty

Incomplete documentation is one of the most common reasons for delayed production approval in industrial assembly. It serves several functions simultaneously. Test reports prove to the customer that all systems have been tested. Parameter lists secure the system's optimal settings and make them reproducible after malfunctions or modifications. Acceptance reports create legal certainty for both parties.

Furthermore, commissioning documentation forms the basis for the entire lifecycle. Maintenance intervals, wear limits, and setpoints from the trial run flow directly into subsequent maintenance and repair processes. Working thoroughly here saves effort during every inspection and troubleshooting task for years to come.

Commissioning for international industrial installations

International industrial installations come with additional requirements. Country-specific standards and safety regulations, varying mains voltages and connection conditions, as well as approvals by local authorities or inspection bodies must be incorporated into the planning at an early stage. The greatest risks usually arise not during the installation itself, but during the preparation phase.

Successful international projects are based on detailed planning, reliable logistics, qualified personnel, and compliance with local regulations. Addressing these points early on significantly increases the probability of success and avoids costly delays in production release.

Commissioning of systems with LIEMONT

As a partner for industrial installations, LIEMONT handles the entire project execution, from planning and mechanical and electrical installation to the commissioning of systems, including functional testing. Commissioning is not a downstream step, but an integral part of our industrial installations, with systematic checks during assembly and before handover.

You can rely on this:

  • Mechanical and electrical from a single source: No loss of efficiency due to interface gaps between assembly, installation, and commissioning
  • Certified processes: ISO 9001:2015, ISO 45001:2018, and SCCp as proof of quality management and occupational safety
  • Comprehensive documentation: Test reports, parameter lists, and acceptance documents as standard
  • International experience: Commissioning in Switzerland, Germany, and internationally, familiar with country-specific regulations
  • Support beyond acceptance: From comprehensive industrial service to regular maintenance of the systems

This ensures your system not only goes into operation on schedule but stays that way.

Conclusion

Commissioning is the most critical phase of any industrial installation: it is the moment of truth where the system proves whether it delivers on the promises made during planning and assembly. A clear process—from mechanical completion and cold/hot commissioning to documented final acceptance—prevents technical defects, rework, and delayed production approval. Realistic timeframes, rigorous testing steps, and comprehensive documentation are essential. By entrusting system commissioning to an experienced industrial installation partner, you shorten the time to production readiness and launch operations with a tested, reliable system.