01
PLANNING
Define requirements
Key inputs
Main work
Required output
Critical controls
Student focus
Customer focus
FROM REQUIREMENT TO FINISHED CASTING
Master foundry process flows, drawing and casting methods.
Follow the technical decisions, production stages and quality checks that turn an engineering idea into a reliable metal component.
INTERACTIVE PROCESS MAP
The complete casting route
Select a stage to inspect its purpose, inputs, outputs and critical controls.
STAGE 02 — ENGINEERING DEFINITION
Manual drawing and CAD
A casting starts as controlled geometry. The drawing communicates what the part must become; the pattern and process design determine how the foundry will produce it.
MANUAL DRAFTING
Build the drawing from first principles
- 1Choose sheet and scale
Select a standard sheet size, title block and a scale that keeps all views legible.
- 2Construct orthographic views
Lay out front, top and side views using projection lines; add sections for internal features.
- 3Apply line conventions
Differentiate visible outlines, hidden features, centre lines, cutting planes and dimension lines.
- 4Dimension functionally
Define sizes and locations from usable datums. Avoid duplicate, missing or ambiguous dimensions.
- 5Add casting information
Identify alloy, general tolerances, machining symbols, draft, parting line and inspection notes.
- 6Check and approve
Verify view agreement, scale, units, revision, material and every dimension needed to inspect the part.
CAD WORKFLOW
Turn design intent into controlled data
- 1Model the finished component
Create sketches and parametric features around design datums and functional relationships.
- 2Run casting design review
Check wall thickness, fillets, undercuts, draw direction, core access, feeding zones and machining stock.
- 3Develop casting and tooling models
Separate the finished-part model from the as-cast model, then create pattern, core-box and mould geometry.
- 4Simulate where justified
Use fill and solidification analysis to investigate turbulence, air entrapment, hot spots and riser performance.
- 5Create production drawings
Generate 2D views, sections, dimensions, tolerances, notes, datums and revision-controlled title blocks.
- 6Export controlled formats
Release PDF for reading, DWG/DXF for 2D exchange and STEP/IGES for neutral 3D exchange.
CASTING-SPECIFIC DESIGN DATA
What the drawing must control
Not every allowance belongs on the final component drawing. The foundry usually converts the approved component definition into an as-cast and tooling definition.
Shrinkage allowance
Pattern dimensions are increased to compensate for alloy contraction during cooling.
Machining allowance
Extra material is placed on surfaces that will be cut to final size and finish.
Draft angle
Taper allows a pattern to withdraw from the mould without damaging the cavity.
Fillets & radii
Rounded transitions improve flow, reduce stress concentration and support sound solidification.
Parting line
The mould separation plane affects draw, flash, mismatch, tooling cost and cleaning.
Cores & core prints
Cores form internal passages; core prints locate and support them within the mould.
Datums & tolerances
Inspection needs clear reference features and realistic geometric or dimensional limits.
Gates, runners & risers
These process features belong on foundry layouts and must support controlled filling and feeding.
Manual drawing versus CAD
| Consideration | Manual drawing | CAD | Good practice |
|---|---|---|---|
| Best use | Learning projection, quick concepts, field sketches | Production definition, complex geometry, revision control | Understand manual principles even when CAD is used |
| Editing | Slower; redraw may be necessary | Fast when the model is well constrained | Record every approved revision |
| 3D understanding | Relies heavily on visualisation skill | Model can be rotated, sectioned and measured | Use sections for hidden cavities in either method |
| Tooling link | Dimensions transferred by the patternmaker | Models can drive CNC, 3D printing and simulation | Never machine directly from an uncontrolled customer file |
| Risk | Construction or transcription error | False confidence in an attractive but uncastable model | Complete a formal drawing and castability review |
PROCESS SELECTION
Choose the right casting route
The best method depends on alloy, size, quantity, geometry, tolerance, surface finish, lead time and tooling budget.
GS
Typical sequence
Strong fit
Watch closely
Quick selection matrix
| Method | Typical volume | Tooling cost | Geometry | Finish / accuracy | Common alloys |
|---|---|---|---|---|---|
| Green sand | Low to high | Low–medium | Simple to complex with cores | Moderate | Iron, steel, aluminium, copper alloys |
| No-bake sand | Low to medium | Low–medium | Large and complex | Moderate–good | Iron, steel, non-ferrous alloys |
| Investment | Low to high | Medium–high | Very complex, thin features | High | Steel, superalloys, aluminium, copper alloys |
| Pressure die | High | High | Complex, thin-walled | High | Aluminium, zinc, magnesium |
| Centrifugal | Medium to high | Medium | Axisymmetric / hollow | Good | Iron, steel, copper alloys |
QUALITY BUILT INTO THE FLOW
Control points that prevent defects
Final inspection cannot repair a weak process. Quality is created by controlling design, materials, moulds, metal, pouring and finishing.
Drawing release
Confirm material, revision, datums, tolerances, machining, acceptance criteria and traceability.
- Contract and feasibility review
- Controlled drawing approval
- Castability sign-off
Mould & core
Stabilise sand properties and verify cavity condition before closing the mould.
- Moisture, strength and compactability
- Core dimensions and coating
- Vents, filters and mould assembly
Molten metal
Release only metal with acceptable chemistry, cleanliness and pouring temperature.
- Charge control and spectrometry
- Temperature measurement
- Degassing, inoculation or treatment
Pouring
Control time, stream, ladle practice and mould identification.
- Pouring temperature and duration
- Stable, non-aspirating stream
- Operator and heat traceability
Final verification
Inspect against drawing and purchase requirements, then document release.
- Visual and dimensional inspection
- NDT and mechanical tests as specified
- Certificates and nonconformance control
DEFECT LOGIC
Trace defects back to the process
| Indication | Possible mechanisms | Evidence to check | Control direction |
|---|---|---|---|
| Gas porosity / blowholes | Moisture, dissolved gas, poor venting, turbulence | Shape and location, sand data, melt treatment, fill pattern | Improve gas control, venting, melt cleanliness and filling |
| Shrinkage cavity | Inadequate feeding or unfavourable thermal gradient | Hot-spot location, riser neck, yield, solidification study | Promote directional solidification and effective feeding |
| Cold shut / misrun | Low fluidity, heat loss, slow or divided streams | Temperature, section thickness, flow length, pouring time | Improve thermal and gating conditions |
| Sand inclusion | Erosion, broken mould/core, poor skimming | Inclusion composition, gate velocity, mould strength | Strengthen mould system and reduce damaging flow |
| Hot tear / crack | Restrained contraction, sharp geometry, weak hot strength | Crack path, radii, mould restraint, shakeout timing | Reduce restraint and smooth section transitions |
| Mismatch / dimensional error | Pattern, core or mould displacement; allowance error | Datum inspection, mould assembly, tooling wear, revision | Improve location, clamping and drawing control |
These are investigation directions, not automatic root-cause conclusions. Confirm causes with process records, sectioning, laboratory evidence and controlled trials.
LEARNING TOOLS
Foundry calculation bench
Use these calculators to explore common relationships. Production values must come from validated plant data and approved procedures.
CUSTOMER BRIEFING
Information a foundry needs for a useful quotation
Complete technical information reduces assumptions, quotation changes and late redesign.
01
Part definitionApproved 2D drawing and, where available, a neutral 3D model. State the controlling document and revision.
02
MaterialAlloy grade and applicable specification, including any chemistry, hardness or mechanical-property requirements.
03
DemandPrototype quantity, order size, expected annual volume and target delivery dates.
04
Service conditionsLoad, temperature, wear, corrosion, pressure, safety significance and expected life where relevant.
05
AcceptanceCritical dimensions, surface finish, heat treatment, NDT, pressure testing, certificates and sampling level.
06
Commercial scopeWho owns tooling, whether machining/coating is included, packaging, delivery point and traceability needs.
STUDENT REVISION
Check your understanding
Choose one answer for each question. Your result includes short explanations.
QUICK REFERENCE
Foundry glossary
Allowance
An intentional dimensional change applied to tooling to account for shrinkage, machining, distortion or mould withdrawal.
Core
A shaped insert placed in a mould to form internal cavities, holes or passages in a casting.
Core print
A pattern feature that creates a mould recess used to position and support a core.
Draft
A small taper on surfaces parallel to the draw direction to help remove the pattern cleanly.
Fettling
Removal of gates, risers, flash and adhering mould material, followed by surface finishing.
Gating system
The network that carries molten metal from the pouring basin through sprue and runners into the cavity.
Inoculation
Controlled addition of nucleating material, commonly to cast iron, to influence solidification structure.
Mould
The body containing the shaped cavity into which molten metal is introduced.
Pattern
Tooling used to form the mould cavity, incorporating appropriate casting and process allowances.
Riser / feeder
A reservoir intended to supply liquid metal to a casting as it contracts during solidification.
Shakeout
Separation of a solidified casting from its mould after adequate cooling.
Metal yield
The useful casting mass expressed as a percentage of the total metal poured into the mould.