618-2037/01 – Molding materials (FM)
Gurantor department | Department of Metallurgy and Foundry | Credits | 7 |
Subject guarantor | Ing. Jaroslav Beňo, Ph.D. | Subject version guarantor | Ing. Jaroslav Beňo, Ph.D. |
Study level | undergraduate or graduate | Requirement | Compulsory |
Year | 2 | Semester | winter |
| | Study language | Czech |
Year of introduction | 2014/2015 | Year of cancellation | |
Intended for the faculties | FMT | Intended for study types | Bachelor |
Subject aims expressed by acquired skills and competences
Acquired knowledge:
- student will be able to characterize individual technologies for molding and core mixture manufacture
- student will be able to define basic methods for testing of molds and cores mixtures together with their regulation based on their physical – chemistry and technological properties.
Acquired skills:
- student will be able to predict mutual interactions of sand – binder system
- student will be able to apply their theoretical knowledge in order to quality control of molding mixture in relation to selected technology
- know the procedure and methodology for complex and time-consuming tests evaluation sand and bentonite mixture based on visual methodology
Teaching methods
Lectures
Individual consultations
Tutorials
Other activities
Summary
The subject is focused on theoretical and practical aspects of moulding mixtures manufacture and control. The attention is devoted to mutual interaction of sand – binder system and to individual technologies of moulds and cores manufacture.
General methods of testing and control of moulding mixtures is also presented here.
Compulsory literature:
Recommended literature:
Way of continuous check of knowledge in the course of semester
E-learning
http://www.fmmi.vsb.cz/cs/urceno-pro/studenty/podklady-ke-studiu/studijni-opory
Other requirements
Elaboration of semestral projects and completion of the interim tests
Prerequisities
Subject has no prerequisities.
Co-requisities
Subject has no co-requisities.
Subject syllabus:
1. Classification of materials for molds and cores manufacture. Composition of molding mixtures. Sands - general characterization, classification. Evaluation of quality of natural and artificial sands. Determination of basic sands parameters
2. Silica sands, genesis, physical – chemistry and technological properties, disadvantages of silica sands and their elimination (defects caused by retarded thermal dilatation)
3. Non - silica sands, natural and artificial sands. Classification, general characterization and possibility of their utilization. Structure of molding mixture. Porosity and permeability of molding mixtures
4. Thermo-physical properties of molding mixtures. Coefficient of thermal accumulation, constant of solidification and determination of solidification time (Chvorinov rule). Specific surface area, methods of its determination, Coefficient of angularity and its influence on technological properties of molding mixture
5. Activation of sand grains, methods and significance. Reclamation of sands, methods and evaluation of quality reclaim. Alternative ways of reclamation. Molding mixture strengths, Adhesion - Cohesion strengths of binders. Activation of artificial resins (silanization), methods.
6. Binder systems of the I.-IV. Generation, general characterization. Clay binders of foundry technology, structure and properties. Role of water in clay minerals. Kinds of water, optimal moisture determination. Clay - water interactions. Montmorillonitic clays - Bentonites
7. Properties of bentonite molding mixtures. Activation of bentonites, mechanism, chemism and its influence on binder quality. Changes of bentonite binder after thermal exposition. Control of green sand systems (JBS). Oolitization, advantages and disadvantages.
8. Additives of green sand system. Carriers of Pyrolysis Carbon (PC), . Other additives of green sand systems. Function and utilization. Theory of LC. Optimal Concentration of PC in a mold, casting defects due to abundance and/or absence of PC. Other additives of JBS.
9. Chemicization of mould and core manufacture. Binder system of the II. Generation – alkali silicates, manufacture, general characterization. Structure of colloidal solution, gelation process Methods and principles of alkali silicates curing
10. CT – and ST – mixtures with alkali silicates. CO2 – process. Self-setting mixtures with liquid hardeners. Problems with collapsibility of mixtures with sodium silicates. Renaissance of mixtures based on sodium silicates. CT- a ST – směsi s alkalickými silikáty. Technology of salt cores preparation, manufacture and utilization.
11. Binder systems of the II. Generation based on organic resins. Moulding and cores mixtures based on phenol – formaldehyde resins. Croning method, preparation, manufacture of shells, defects and reclamation.. HOT-BOX method and its versions. Gisag COLD-BOX method (No - bake ). Selection of suitable sands, collapsibility and reclamation. Advantages and disadvantages.
12. Molding and cores mixtures based on furan resins. ST - furan mixtures. Types of acid catalysts. Influence of components temperature on run and velocity of process. Reclamation with utilization of multistage magnetic separation. Quality of chromite reclaims. Resol – CO2 process Selection of suitable sands, collapsibility and reclamation.
13. Chemistry of polyurethane binders. Alkyd-oil polyurethanes. Phenol polyurethanes. Methods of core manufacture PUR COLD-BOX, PEP-SET. Saccharide binders and additives.
14. Binders systems of the III. and IV. Generation, application of physical and biological ways of binding for mold manufacture. Principle, utilization, advantages and disadvantages of individual technologies.
Conditions for subject completion
Occurrence in study plans
Occurrence in special blocks
Assessment of instruction