| 1922 | Start-up of the company Brockhaus & Co. GmbH with Fred Cetto as chief engineer Major focus: Manufacturing of immersed welding electrodes, sale of welding machines and repair welding |
| 1923 | Renaming to “Elektrische Schweißbetriebe Cetto und Gärtner” |
| 1936 | Heinrich Dehnhardt took over the company from Fred Cetto and managed the business |
| 1946 | Max Dehnhardt enters the parental business and becomes the sole responsible for the fortune of CETTO for the next 45 years. The product mix was extended by the “Riecetto process” – a process suitable for non-weldable cast material |
| 1961 | Relocation to Ratingen on the Dechenstraße 15 |
| 1981 | Dr. Stefan Dehnhardt starts the activity as engineer/professional welding engineer in the family business of his father and takes over the management of the company in the course of time. |
| 1992 | Setting up of the measuring technology department and marketing of radiation detectors in the steel and recycling industry |
| 2007 | Establishment of the division „Lagerrekonditionierung“ – roll bearing reclamation – in partnership with bearing manufacturer TIMKEN |
| 2012 | Barbara Rübbelke-Dehnhardt starts to manage the business of her deceased husband Dr. Stefan Dehnhardt |
| 2017 | Lukas Rübbelke joins the board. |
| 2023 | Currently about 45 employees are working in the production and administration of CETTO AG |
