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Metal Casting by the Numbers
Melting, charge blending, patterns, gating, solidification, risers, gas and grain, heat treatment and inspection for sand castings
How a sand casting is made right: melt energy and cycle, charge blending, pattern allowances, gating, Chvorinov's rule, riser feeding, gas and grain, T6 heat treatment and Brinell checks.
Start readingAbout this book
A casting is decided in the few minutes it takes metal to fill a mould and freeze. Whether it comes out sound, the right size and the right strength depends on decisions made long before: how the metal was melted and alloyed, how big the pattern was made, how the gating brings the metal in, which parts freeze last and whether a riser feeds them, whether the melt carried gas, and how the casting was heat treated. Each of those decisions has a few numbers behind it, and most foundry defects can be traced to one of them being wrong.
This book works through those numbers, stage by stage, for one aluminium sand casting. It starts with the physics of freezing: latent heat, freezing range and the three stages of shrinkage. It then follows the casting from the furnace, through charge blending, patternmaking, gating, solidification and feeding, to the melt-quality problems that feeding cannot cure, heat treatment and final inspection.
It is for foundry engineers and supervisors, patternmakers, manufacturing and quality engineers, and the designers and buyers who specify castings. It assumes school physics and algebra. Each chapter works the running case with real numbers, includes one plausible mistake and how it was found, links the KEVOS® tools that do the chapter’s calculations, and ends with an exercise and its worked answer.
The running case
Every chapter follows one casting. This is an illustration. A jobbing foundry in Ballarat, Victoria, makes GB-12, a gearbox cover for a machinery builder.
- Alloy and temper: an aluminium–silicon–magnesium casting alloy of the Al–7Si–0.35Mg type, heat treated to T6.
- Casting: finished envelope 300 × 200 × 100 mm, 6 mm walls and a heavy bearing boss; 6.68 kg as cast; 12.1 kg poured per mould with two risers and the gating, a yield of 55%.
- Melting: a 100 kW electric crucible furnace melting 150 kg charges of returns and new ingot.
- Production: 60 castings a shift, sand moulded with a resin-bonded core, solution treated, quenched and aged in batches of 40.
- Specification: 75 to 95 HBW after heat treatment, sound bearing boss, pressure-tight walls.
Temperatures, properties, constants, efficiencies, prices, test results and times are the case foundry’s working figures or are calculated from stated assumptions. They do not describe KEVOS® work or any real foundry, customer or alloy supplier’s data.
How to use the book
Read Chapter 1 first: freezing, latent heat and shrinkage underlie every later chapter. Chapters 2 and 3 cover the melt; Chapters 4 to 7 the mould, from pattern to risers, and are best read in order; Chapter 8 covers the defects that come from the melt; Chapters 9 and 10 cover heat treatment and inspection.
Every calculation in the book was checked by running it, and the KEVOS® tools linked from each chapter were checked against the calculations they perform. The methods are the classical ones of foundry practice: Bernoulli for gating, Chvorinov for freezing time, feed-volume and modulus checks for risers. They are sound first estimates and teaching tools; trial castings, sections and simulation decide the real design.
Source limits and professional responsibility
This book is educational. Its methods estimate melt energy, allowances, gating, freezing and feeding for ordinary sand castings, and each chapter says where they stop being reliable. Real castings are proved by trial, sectioning, radiography and testing against the customer’s specification, and alloy data, heat-treatment procedures and inspection rules come from the alloy supplier, the applicable standards and the customer. Molten metal, furnaces, quench tanks and lifting are serious hazards, managed under the model WHS laws by competent people. Decisions about real castings and foundry operations remain with those responsible for them.
Who this book is for
Foundry engineers and supervisors, patternmakers, manufacturing and quality engineers, and designers and buyers of castings who want to understand how a sound casting is planned, made and proved.
What you will learn
- Work out the energy, time and cost of a melt, the furnace's cycle and output per shift, and the energy behind each casting.
- Blend charge materials to a target composition allowing for melt loss, and size a pattern with machining and shrinkage allowances.
- Size a gating system for a pouring time and a safe gate velocity, and predict freezing order with the casting modulus and Chvorinov's rule.
- Design risers that pass both the modulus and feed-volume checks, and tell gas porosity from shrinkage porosity at the furnace and in a section.
- Plan solution, quench and ageing loads, and prove castings with valid Brinell tests, radiography, pressure tests and records.
Inside this book
Chapters
- 01From liquid to solidWhat a foundry has to control when metal freezes in a mould: latent heat, freezing range, the three stages of shrinkage, and why most casting defects are decided by how the metal solidifies.
- 02Melting: energy, time and costHow much energy, time and money each melt takes: the heat balance of a charge, furnace efficiency, the melting cycle with charging and tapping, metal per shift, and energy per casting.
- 03Getting the chemistry rightMaking up a charge that pours to the right composition: blending returns and ingot by alligation, allowing for melt loss, correcting a low melt, and elements that build up with remelting.
- 04Patterns and allowancesSizing a pattern so the casting comes out right: shrinkage and machining allowances, draft and cores, casting mass and metal poured, and a pattern made to the wrong shrinkage rule.
- 05Gating: filling the mouldSizing a gating system so the mould fills in time without turbulence: metal velocity from the head, the choke area for a pouring time, gating ratios, gate velocity, and oxide films from fast metal.
- 06Solidification time and Chvorinov's ruleHow long each part of a casting takes to freeze: the casting modulus, Chvorinov's rule, measuring the mould constant, freezing order, and a riser that froze before the section it fed.
- 07Risers and feedingSizing risers that hold enough metal as well as freezing last: feed volume from shrinkage and efficiency, feeding distance, metal poured, yield, and a riser that piped into the casting.
- 08Defects: gas, oxides and grainRecognising and preventing the defects feeding cannot cure: hydrogen gas porosity and the reduced-pressure test, oxide films, telling gas from shrinkage, and measuring grain refinement.
- 09Heat treating castingsSolution treating, quenching and ageing aluminium castings: what each step does, the furnace energy and cycle time per load, the quench tank's heat balance, and a tank too small for the load.
- 10Inspecting and proving castingsShowing castings meet their specification: Brinell hardness and its validity rules, X-ray and pressure tests, first-article layout, sampling, and a hardness reading taken too near an edge.
Apply This in Practice
Use these KEVOS® tools to try the method from this reading with your own numbers.
Applies this method
Brinell Hardness Test Check (Hardness, Validity Rules, Specification)
Calculates Brinell hardness from two indentation diameters and checks the indentation ratio, thickness, edge distance and spacing rules and the specification.
Used in Inspecting and proving castings
Applies this method
Casting Gating System Choke Area
Sizes the choke for a pouring time from metal velocity under the head, with sprue diameter, runner and gate areas, and checks the velocity at the gates.
Used in Gating: filling the mould
Applies this method
Casting Pattern Plan (Machining Allowance, Shrinkage, Casting and Pour Weight)
Gives casting and pattern dimensions of a block casting from machining and shrinkage allowances, then casting mass, metal to pour for a yield and a ladle check.
Used in Patterns and allowances
Applies this method
Casting Pour Plan (Riser, Feed Volume, Gating and Ladle)
Checks a riser's modulus and its volume against the feed the casting's shrinkage needs, and gives metal poured, casting yield, choke area and a ladle check.
Used in Risers and feeding
Applies this method
Casting Solidification Time and Riser Check
Gives casting and riser moduli and solidification times by Chvorinov's rule and checks the riser-to-casting modulus ratio.
Applies this method
Energy and Time to Melt Metal
Works out the heat to warm, melt and superheat a charge, the latent heat share, the energy drawn at a furnace efficiency, the melting time and the energy cost.
Used in From liquid to solid
Applies this method
Grain Size Acceptance (Field Readings, Average ASTM Grain Size, Spread, Specification)
Averages up to five grain size field readings, converts them to ASTM grain size number G, and checks the average and the spread against a specification.
Used in Defects: gas, oxides and grain
Applies this method
Heat-Treatment Furnace Load Plan (Time, Energy, Cost)
Estimates heat into a furnace load, heat-up time, cycle time, energy and cost per load and per kg of work, including the basket and standing losses.
Used in Heat treating castings
Applies this method
Melt Charge Blend (Two Materials to a Target Content, Batch Masses, Cost)
Blends two charge materials to a target content by alligation, allowing for melt loss, and gives each material's mass and the charge cost per kg.
Used in Getting the chemistry right
Applies this method
Melting Furnace Batch Plan (Energy, Melt Time, Melts per Shift, Cost)
Adds charging and tapping time to the melt heat balance to give the cycle per melt, complete melts and metal per shift against demand, and energy cost per kg.
Used in Melting: energy, time and cost
Applies this method
Pattern Size for Shrinkage and Casting Weight from Pattern
Gives one pattern dimension from the finished size, machining allowance and shrinkage allowance, and estimates casting weight from the pattern's weight.
Used in Patterns and allowances
Applies this method
Quench Tank Temperature Check (Equilibrium Temperature per Load, Loads to the Limit, Cooling Duty)
Finds the quench bath temperature after a hot load, the rise per load, loads before the bath limit and the average heat input against the cooler.
Used in Heat treating castings
References and source notes
The manuscript and worked examples are original KEVOS® writing. References inform particular concepts; their authors do not endorse this book. Web references were consulted on 31 October 2026.
- H. Kleinert, World Scientific, Singapore. Gauge Fields in Condensed Matter, Volume I: Superflow and Vortex Lines (Disorder Fields, Phase Transitions) (1989). In copyright. Used only as a map for the physics behind Chapters 1 and 8: the difference between first-order transitions with latent heat, such as freezing, and the continuous transitions the book treats, and the role of nucleation and order. No text, equations, figures or problems are reproduced, and all cases and calculations are KEVOS® originals.
- N. Chvorinov, Die Giesserei, volume 27. Theorie der Erstarrung von Gußstücken (1940). Named in Chapter 6 as the origin of the rule that solidification time is proportional to the square of the casting modulus.
- J. Campbell, Butterworth-Heinemann. Complete Casting Handbook: Metal Casting Processes, Metallurgy, Techniques and Design (2011). Background for filling, oxide films and the double-film mechanism, gate velocities, feeding and hydrogen porosity in aluminium alloys in Chapters 5, 7 and 8.
- ASM International. ASM Handbook, Volume 15: Casting (2008). Background for melting, patternmaking allowances, gating and risering practice, grain refinement, modification and heat treatment of aluminium castings in Chapters 2 to 9.
- ASTM International. ASTM E155 Standard Reference Radiographs for Inspection of Aluminum and Magnesium Castings (2020). Named by number and scope only in Chapter 10 as an example of reference radiographs used to grade casting radiographs. No image or severity level from it is quoted.
- International Organization for Standardization. ISO 6506-1 Metallic materials — Brinell hardness test — Part 1: Test method (2014). Named by number and scope only in Chapter 10 as the test method standard behind the Brinell validity rules. The rule values in the case are the case foundry's settings in the KEVOS® tool, not quotations from the standard.
- Safe Work Australia. Model Code of Practice: Managing the risks of plant in the workplace (2022). Named in Chapters 2 and 9 for the duty to manage the risks of plant, including furnaces, cranes and quench tanks, under the model WHS laws.