Course detail
Casting Defects and Repairs
FSI-PVD Acad. year: 2020/2021 Summer semester
The students are familiarized with the classification and terminology of casting defects in keeping with Czech and international standards. The basic types of defects occurring in castings are described, and the physical and chemical causes of their appearance during individual stages of the production cycle are analysed with emphasis on prevention. Experimental studies concern temperature fields in the mould/casting system, the appearance of foundry mould condensation zone, and the appearance of stress in the casting. The process of melt reoxidation, penetration into the mould face, and formation of air pockets are analysed via mathematical modelling on PC.
Language of instruction
Czech
Number of ECTS credits
6
Supervisor
Department
Learning outcomes of the course unit
The course will provide students with the knowledge necessary for determining the kind of casting defect, the reasons for its appearance, and taking remedial measures.
Prerequisites
Students must have the knowledge of the thermodynamics of metallurgical processes (properties of real solutions, the criterion of the progress and equilibrium of metallurgical processes, equilibria in the melt/gas and melt/refractory systems), the technology of mould and core production (inclusive of the properties of moulding materials), casting and finishing operations in the production of castings, and the metallurgy of foundry alloys.
Planned learning activities and teaching methods
The course is taught through lectures explaining the basic principles and theory of the discipline. Exercises are focused on practical topics presented in lectures. Teaching is suplemented by practical laboratory work.
Assesment methods and criteria linked to learning outcomes
Condition of awarding the course-unit credit: participation in exercises. Examination: the knowledge of physical-chemical causes of the appearance of basic types of casting defects, remedial measures preventing their appearance, and basic ways of repairing them will be tested.
Aims
The objective is to make students familiar with the basic types of casting defects and the main reasons for their appearance during individual production stages. They will be led to comprehend the complicated physical-chemical interactions between melts and the surrounding environment (atmosphere, foundry mould) and their effect on the quality of castings.
Specification of controlled education, way of implementation and compensation for absences
Attendance in lectures is recommended, attendance in exercises is obligatory.
Attending at the exercises is required, being checked by the leader of practicals. In the case of absence from exercises, the leader assigns a topic for independent written work.
The study programmes with the given course
Programme M2I-P: Mechanical Engineering, Master's
branch M-SLE: Foundry Technology, compulsory
Type of course unit
Lecture
26 hours, optionally
Teacher / Lecturer
Syllabus
1. Defects arising during the production of patterns and foundry moulds, and while handling them.
2. Casting, heat and mass transport between the melt and the surrounding environment.
3. Defects arising during pouring.
4. Thermal and mechanical loading of moulds, condensation zone, scabs.
5. Melt reoxidation, secondary slag, oxide skins, inclusions.
6. Mechanical, thermal and physical-chemical conditions of melt penetration into the mould, surface defects.
7. Endogenous pockets of oxygen, nitrogen, and hydrogen; pinholes.
8. Gas distribution in foundry mould walls, exogenous pockets
9. Melt crystallization, defects in macrostructure and microstructure, segregation.
10. Solidification of castings, contraction cavities.
11. Cooling of castings, appearance of cracks.
12. Basic ways of repairing of castings.
13. Basic ways of repairing of castings.
Laboratory exercise
8 hours, compulsory
Syllabus
1. The temperature field in the mould wall (laboratory measurement).
2. Repairs of defects in castings.
3. Repairs of defects in castings.
4. Application of X-ray microanalysis and X-ray diffraction.
Exercise
4 hours, compulsory
Teacher / Lecturer
Syllabus
1. Definition of the quality of castings, delimitation by means of standards, technical drawings, and technical acceptance terms.
2. Technological aspects of the design of a casting.
Computer-assisted exercise
14 hours, compulsory
Syllabus
1. Modelling the progress of reoxidation processes in the Mathcad program environment.
2. Modelling the blocking of oxygen blowholes appearance in the Mathcad program environment.
3. Modelling the pressure relations accompanying the appearance of nitrogen and hydrogen blowholes in the Mathcad program environment.
4. Modelling the loss of pressure in gating system in the Mathcad program environment
5. Modelling the progress of melt penetration into the casting wall in the Mathcad program environment.
6. Evaluation of the data file of the temperature field in the walls of castings, using the Mathcad program environment.
7. Evaluation of the data file of the temperature field in the mould wall, using the Mathcad program environment.