The Department of Machine Elements has a 40-year independent history in the development of research activities in almost all areas of the scientific specialty "Mechanical Engineering and Machine Elements". In 1998, the laboratory of "Technology and Techniques of Non-Metallic Materials" joined the department as part of its teaching and research staff and material base. This merger significantly expanded and enriched the scope of scientific research in the new Department of "Machine Elements and Non-Metallic Structures". 
 
 In the merged department, in addition to and together with machine elements, two other scientific directions are developed: "Polymer Materials and Composites" and "Non-Destructive Testing and Diagnostics of Materials, Components and Products".

 How did it all begin?
 In 1947, by decision of the Council of Ministers, departments were established at the Faculty of Mechanical Engineering of the State Polytechnic. Among them was the Department of "General Mechanical Engineering and Lifting Mechanisms" - this is actually the prototype of the current Department of Machine Elements and Non-Metallic Structures (MENK).

 In 1956, the teachers of Machine Drawing joined the newly established Department of "Descriptive Geometry and Machine Drawing". As a result of this change, the main department took the name "Machine Elements and Lifting-Transport Facilities", which clearly outlined its profile.

Six years later, in 1962, a new structural separation was carried out – an independent department of "Lifting-Transport, Construction and Mining Machines" was separated. The main department changed its name to "Machine Elements and Theory of Mechanisms and Machines", reflecting the expansion of its thematic scope.

In 1968, part of the teaching staff moved to the newly opened Department of "Mechanical Instrumentation", which further differentiated the training directions and scientific research.

In 1974, a significant change occurred – the department was divided into two independent units: the Department of "Machine Elements", which remained at the Faculty of Mechanical Engineering, and the Department of "Theory of Mechanisms and Machines", which moved to the Machine-Technological Faculty. This decision allowed for more targeted development of each direction.

In 1997, by decision of the Faculty Council, a new merger took place – the Department of Machine Elements and the Educational Laboratory of Non-metallic Materials and Structures combined their efforts into a new structure called "Machine Elements and Non-metallic Structures".

In previous years, the department was headed by:

* Prof. Eng. Georgi Emanuilov Angelov: 1947-1969

* Assoc. Prof. Eng. Aleksandar Georgiev Vrigazov: 1969-1973

* Assoc. Prof. Eng. Mikhail Spirov Konstantinov: 1973-1974

* Assoc. Prof. Eng. Petko Valev Jordanov: 1974-1989

* Assoc. Prof. Dr. Eng. Georgi Nikolov Dimchev: 1989-1992

* Assoc. Prof. Dr. Eng. Nikola Hristov Atanasov: 1992-2009

* Assoc. Dr. Eng. Dimitar Nikolov Ralev: 2009 - 2014

* Assoc. Dr. Eng. Valentin Kamenov Dikov: 2009 - 2018

* Assoc. Dr. Eng. Georgi Petrov Tonkov: 2018 - present

International Relations

The international cooperation of the Department of Machine Elements has developed in the following areas:

Programs and agreements on bilateral cooperation between individual departments, universities or institutes: