In brief
Retrofit refers to modernising existing machines with new controls, drives or safety technology instead of replacing them entirely.
Contents
What is Retrofit?
In a retrofit, the basic mechanical structure of a plant is retained while outdated or discontinued components are replaced with current technology. Typical triggers are controls and drives that are no longer available, higher demands on performance, energy efficiency or connectivity, and upgrades to safety technology. A retrofit is to be distinguished from an overhaul, which restores the original condition, and from a new purchase.
A retrofit frequently covers replacing the controller and operator panel, inverters and motors, sensors, fieldbus systems and control cabinet components, sometimes also hydraulics or pneumatics. The existing installation, documentation and interfaces are surveyed beforehand. Where changes are extensive, it must be checked whether the machine has undergone a substantial modification, which may entail a new risk assessment and conformity assessment. The applicable legal framework is decisive; in case of doubt, expert advice should be sought.
For spare parts supply, a retrofit is often the answer to obsolescence: instead of permanently searching for scarce legacy parts, the plant is converted to current, readily available components.
In practice: maintenance and procurement
A retrofit should begin with a list of all discontinued and hard-to-source parts, as this shows where the need for action is greatest. Until the conversion, a targeted stock of critical legacy parts helps keep the plant running safely.
Synonyms and abbreviations: machine modernisation
Frequently asked questions
What is the difference between a retrofit and an overhaul?
An overhaul restores a machine to its original condition by replacing wear parts and reconditioning assemblies. A retrofit, by contrast, modernises the machine with new technology, such as a current controller or more efficient drives. In practice, the two are often combined: the mechanics are overhauled while the electrics and controls are renewed.
When is a retrofit worthwhile?
A retrofit is usually worthwhile when the mechanics of a plant are still in good condition but the controls or drives are outdated or can no longer be sourced. The deciding factors are the comparison with a new purchase, the remaining service life, downtime risks due to missing spare parts and possible improvements in performance and energy consumption.
Does a retrofit require new CE marking?
That depends on whether the changes count as a substantial modification. If, for example, function, performance or the safety concept are altered in such a way that new hazards arise, a renewed conformity assessment may be required. The classification is made case by case on the basis of the applicable regulations; this entry does not replace a legal review.
Which components are typically replaced in a retrofit?
Most often, controllers, operator panels, frequency inverters, servo and induction motors, sensors and fieldbus components are replaced. Safety technology such as safety controllers and light curtains, as well as control cabinet components, are often added. Main mechanical assemblies such as the frame, guides and gearboxes are generally retained and overhauled if necessary.