20.2 Foundry Materials, Casting, Solidification & Defects

PRC Mining Engineer Licensure Examination Philippines

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1 Chapter 1: Surface Mining Methods & Pit Optimization

1.1 Surface Mining Unit Operations & Method Selection 1.2 Bench Geometry, Slope Stability & Geotechnical Pit Design 1.3 Cut-Off Grade Optimization & Lerchs-Grossmann Pit Limits

2 Chapter 2: Underground Mining Methods & Strata Control

2.1 Underground Mining Method Classification & Selection 2.2 Rock Mechanics, Stress Analysis & Strata Control 2.3 Underground Ground Support Systems & Excavation Design

3 Chapter 3: Materials Handling, Equipment & Mine Economics

3.1 Drilling, Blasting & Explosives Engineering 3.2 Mine Loading, Haulage & Materials Handling Systems 3.3 Mine Capital (CAPEX), Operating Costs (OPEX) & Financial Evaluation

4 Chapter 4: Mine Safety, Ventilation & Philippine Mining Laws

4.1 Mine Ventilation Network Analysis & Environmental Quality 4.2 Philippine Mine Safety Rules, Health & Disaster Prevention 4.3 Philippine Mining Act of 1995 (RA 7942), DAO 2010-21 & Mining Ethics

5 Chapter 5: Physical Geology, Mineralogy & Philippine Deposit Types

5.1 Structural Geology, Tectonics & Ore Controls 5.2 Igneous, Metamorphic & Sedimentary Ore Mineralogy 5.3 Major Philippine Ore Deposit Models

6 Chapter 6: Mineral Exploration, Geophysics & Core Logging

6.1 Geochemical & Remote Sensing Exploration Techniques 6.2 Geophysical Exploration Methods in Mining Geology 6.3 Diamond Drilling, Core Logging & QA/QC Protocols

7 Chapter 7: Geostatistics, Resource Estimation & PMRC Code

7.1 Ore Body Block Modeling & Spatial Variography 7.2 Inverse Distance & Ordinary Kriging Grade Estimation 7.3 Philippine Mineral Reporting Code (PMRC 2020) & Resource Classification

8 Chapter 8: Comminution, Sizing & Physical Mineral Separation

8.1 Crushing, Grinding & Bond Work Index Calculations 8.2 Particle Screening, Hydrocyclone Classification & Sizing 8.3 Gravity Concentration & Magnetic/Electrostatic Separation

9 Chapter 9: Froth Flotation & Extractive Hydrometallurgy

9.1 Froth Flotation Chemistry, Reagents & Cell Kinetics 9.2 Leaching Technologies (Heap, Agitation & Tank) 9.3 Precious Metal Recovery: CIP, CIL, Merrill-Crowe & Electrowinning

10 Chapter 10: Process Plant Flowsheets & Environmental Tailings Management

10.1 Metallurgical Plant Flowsheets & Pulp Mass Balances 10.2 Tailings Storage Facility (TSF) Design & Dam Safety 10.3 Acid Mine Drainage (AMD) Mitigation & Environmental Protection (EPEP/FMR/DP)

11 Chapter 11: 2025 PRC Blueprint, Prospecting Tools & Exploration Decisions

11.1 Official 2025 TOS, Three-Paper Structure & Exam Strategy 11.2 Prospecting Instruments, Base Maps & Surface Geological Mapping 11.3 Integrating Direct and Indirect Evidence for Exploration Decisions

12 Chapter 12: Mine Infrastructure, Sustainable Development & Climate

12.1 Power, Water, Drainage & Support-Facility Selection 12.2 Sustainable Development, Progressive Rehabilitation & Community Impact 12.3 Mining, Climate, Reforestation, Coal & Energy-Transition Minerals

13 Chapter 13: Mine Valuation, Financial Analysis & Due Diligence

13.1 Time Value of Money, Future Value & Present Value 13.2 Financial Statements, Mine Economics & External Price Drivers 13.3 Exploration Provenance, Technical Review & Legal Due Diligence

14 Chapter 14: Mine Organization, Communication & Accountable Leadership

14.1 Line and Staff Functions in a Mining Organization 14.2 Communication With Superiors, Peers & Subordinates 14.3 Authority, Responsibility, Delegation & Safety Accountability

15 Chapter 15: Philippine Mining Law, Indigenous Rights & Professional Ethics

15.1 Legal Hierarchy, Mineral Tenure & Compliance Analysis 15.2 Constitutional Participation, IPRA, FPIC & Ancestral Domains 15.3 RA 4274, Professional Scope, Ethics & Document Integrity

16 Chapter 16: Applied Mathematics & Mine Surveying

16.1 Engineering Mathematics for Safe, Efficient Mine Decisions 16.2 Survey Control, Instruments, Traverses & Error Adjustment 16.3 Topographic Maps, Underground Set-Out & Survey Timeliness

17 Chapter 17: Feasibility Studies, Data Quality & Project Decisions

17.1 Scoping, Pre-Feasibility & Final Feasibility Study Maturity 17.2 Data Accuracy, Assumption Control & Go/No-Go Decisions 17.3 Multidisciplinary Integration, Interfaces & Independent Review

18 Chapter 18: Mining Computer Applications, Digital Control & Global Developments

18.1 Computer Functions, Office Applications & Data Governance 18.2 Geological Modeling, Mine Planning, Scheduling & Valuation Software 18.3 Real-Time Control, Critical Minerals & Regional Mining Developments

19 Chapter 19: Earth Systems, Geologic Time & Philippine Hazards

19.1 Solar-System Origin, Earth Interior & Atmospheric Layers 19.2 Rock Cycle, Landforms & the Geologic Time Scale 19.3 Philippine Tectonics, Geologic Hazards & Mitigation

20 Chapter 20: Metallurgy, Foundry Practice & Assaying

20.1 Extractive, Physical & Adaptive Metallurgy Principles 20.2 Foundry Materials, Casting, Solidification & Defects 20.3 Sampling, Fire Assay, Cupellation, Parting & Assay Calculations

21 Chapter 21: Solid–Liquid Separation, Environmental Law & Mine Ecology

21.1 Thickening, Filtration & Solid–Liquid Separation 21.2 Philippine Air, Water, Waste & Hazardous-Substance Controls 21.3 Mine Ecology, Closure, Tailings, Waste & Community Livelihood

20.2 Foundry Materials, Casting, Solidification & Defects

Key Takeaways Explain This Topic AI

Casting pours molten metal into a mold where heat transfer, nucleation, growth, feeding and contraction determine structure and defects.

A pattern creates the mold cavity with allowances for shrinkage, machining and draft; cores form internal passages and the gating system controls metal flow.

Risers feed liquid metal during solidification shrinkage and should remain molten longer than the casting region they serve.

Common defects include shrinkage cavities, gas porosity, inclusions, cold shuts, misruns, hot tears and sand defects, each requiring cause-based correction.

Foundry safety controls moisture, charge condition, furnace integrity, refractory, lifting, temperature, fumes, dust, personal protection and exclusion from molten-metal paths.

Last updated: August 2026

Foundry work produces complex metal shapes by melting an alloy, delivering it into a prepared mold and controlling solidification. Mining applications include crusher components, pump parts, liners, wheels, gears and wear-resistant castings. Process control must deliver geometry, soundness, chemistry and mechanical properties—not simply fill a cavity.

Pattern, Mold and Core

A pattern is the model used to form the mold cavity. It incorporates:

• shrinkage allowance for contraction;
• machining allowance for surfaces finished later;
• draft for pattern withdrawal;
• distortion allowance where shape may warp; and

core prints to locate cores.

A core forms an internal hole or passage. Green-sand molds use sand, binder, water and additives; chemically bonded molds and permanent molds suit other sizes and quality requirements. Mold strength, permeability, collapsibility, refractoriness and moisture must be controlled.

Gating and Feeding

The pouring basin, sprue, runner, gates and filters deliver metal. The design should fill the mold before premature freezing while limiting turbulence, air aspiration, oxide entrainment and mold erosion. A tapered sprue helps prevent aspiration as the stream accelerates.

A riser or feeder supplies liquid metal to compensate for volumetric contraction during solidification. It must solidify after the casting region it feeds. Chills can accelerate local solidification and promote directional freezing toward the riser.

Solidification Time

Chvorinov's rule relates solidification time to volume-to-surface-area ratio: t s = C m ( V A ) n t_s=C_m\left(\frac{V}{A}\right)^n t s ​ = C m ​ ( A V ​ ) n

where C m C_m C m ​ depends on mold and metal and n n n is often near 2. A riser with larger modulus V / A V/A V / A than the casting remains liquid longer. Geometry can create isolated hot spots that form shrinkage even when total riser volume seems adequate.

• Production Sequence
• pattern and core design;
• mold and core preparation;
• charge selection and furnace melting;
• chemistry adjustment, deoxidation or inoculation;
• temperature measurement and slag removal;
• controlled pouring;
• solidification and cooling;
• shakeout and core removal;
• gate/riser removal, cleaning and finishing;
• heat treatment where required; and

dimensional, nondestructive and mechanical inspection.

Charge materials must be identified and dry. Alloy chemistry can drift through oxidation, contamination or wrong scrap. Excess superheat increases energy, oxidation, gas pickup and mold reaction; inadequate temperature causes misrun or cold shut.

Defects and Causes

• Defect Appearance/mechanism Possible controls
• Shrinkage cavity Void at hot spot lacking feed Riser/modulus, chills, directional solidification
• Gas porosity Rounded pores from dissolved or entrained gas Dry charge/mold, degassing, calmer flow
• Inclusion Slag, oxide or sand trapped Clean melt, filters, gating, mold strength
• Misrun Cavity not completely filled Temperature, fluidity, section/gate and fill time
• Cold shut Streams meet but do not fuse Flow path, temperature and gating
• Hot tear Crack during constrained contraction Geometry, mold collapsibility, alloy and cooling
• Metal penetration/burn-on Metal enters sand pores Sand size, coating, temperature and compaction

Do not repair a recurring defect by welding every casting without identifying cause. Use defect maps, process data and metallography.

Structure and Properties

Cooling rate affects grain size and phase distribution. Fast cooling generally refines structure, while thick sections cool slowly. In cast iron, composition, cooling and inoculation influence graphite form and matrix. Heat treatment can relieve stress or modify hardness and toughness. Confirm properties with hardness, tensile or impact testing and appropriate metallography.

Nondestructive testing includes visual, dye penetrant, magnetic particle, ultrasonic and radiographic methods according to material and defect orientation. No single method finds every defect.

Foundry Safety

Molten metal contacting water can cause explosive steam expansion. Keep charge, tools, ladles and floors dry. Inspect furnace lining, lifting gear, ladles and trunnions; control exclusion zones and travel paths. Provide heat and face protection, ventilation for metal and binder fumes, dust control, spill containment, emergency response and trained signals.

Worked Modulus Comparison

If a casting section has modulus V / A = 1.5 V/A=1.5 V / A = 1.5 cm and a riser has 2.0 cm, with common C m C_m C m ​ and n = 2 n=2 n = 2 , the time ratio is ( 2.0 / 1.5 ) 2 = 1.78 (2.0/1.5)^2=1.78 ( 2.0/1.5 ) 2 = 1.78 . The riser should remain molten about 1.78 times longer, though neck design and heat loss still require engineering review.

Casting Yield

Casting yield is sound casting mass divided by total poured metal, including gates and risers. Improving yield reduces remelt energy, but shrinking a riser without solidification analysis can create cavities. Optimize gating and feeding while preserving directional solidification and quality; recycled returns still require energy and can introduce chemistry or inclusion risk.