An equipment needs two very different families of agricultural machinery iron casting: wear parts that survive soil abrasion and structural housings that hold loads, seal oil, and align gears. This guide shows what to use where, with material options, design rules, test plans, and cost levers you can act on today.
Table of contents
- Quick definitions & examples
- Material choices that actually work
- Design rules: wear parts vs structural housings
- Wall thickness & minimums by process
- Tolerances, surface finish, and machining stock
- Quality & testing plans (what to specify)
- Cost & sourcing tips
- FAQs
Quick definitions & examples
Quick definitions & examples
Plowshares, points, cultivator teeth, scraper shoes, chopper knives, wear liners, bimetal inserts.
Structural housings (load-bearing/precision)
Gearbox/transmission housings, axle/differential cases, pump/valve bodies, motor/drive endbells, frames and brackets.
Material choices that actually work
Table A — Typical iron materials for ag castings
| Casting type | Common materials & specs | Typical hardness | Notes |
|---|
| Wear parts | High‑Cr white iron (ASTM A532 Cl II/III), Ni‑Hard; bimetal (white‑iron face + ductile‑iron backing) | HRC 58–64 (≈ 630–720 HV) | Exceptional abrasion resistance; limited machinability; avoid sharp transitions; pre‑heat for welding/brazing only if allowed |
| ADI (Austempered Ductile Iron) per ASTM A897 / EN 1564 | 269–477 HBW (grade‑dependent) | Balance of wear + toughness; can be machined pre‑austemper; watch section size for through‑hardening |
| Structural housings | Ductile iron per ASTM A536 (e.g., 65‑45‑12, 80‑55‑06) / EN 1563 (EN‑GJS grades) | 170–300 HBW (as‑cast/normalized) | Good strength, elongation; excellent machinability; leak‑tightness achievable |
| Gray/grey iron per ASTM A48 (Class 30–40) | 170–230 HBW | Damping & machinability; use where tensile load is moderate |
Tip: For extreme abrasion, consider bimetal wear parts: cast a white‑iron wear face metallurgically bonded to a ductile‑iron base for bolt‑on mounting and shock absorption.
Design rules — wear parts vs structural housings
Wear parts (abrasion‑centric)
- Simple, replaceable geometry with generous radii; avoid thin, fragile tips unless backed.
- Section thickness ≥ 10–12 mm (0.39–0.47 in) for high‑Cr white iron to reduce cracking risk.
- Use draft 1.5–2.5° to ease knock‑out; keep uniform thickness to minimize residual stress after heat treat.
- Mounting strategy: slots/holes in the ductile‑iron backing (for bimetal) to keep the hard face un‑drilled.
- Heat treatment: austempering cycles for ADI per ASTM A897 grade; cool rate matched to section.
Structural housings (precision‑centric)
- Uniform walls with R ≥ 3–5 mm (0.12–0.20 in); ribbing for stiffness instead of mass.
- Datum scheme for single‑setup machining; minimize stock (see table).
- Leak‑tight design for oil circuits; avoid blind hot spots; place bosses near ribs for feed.
- Threaded inserts or cored holes sized for standard taps to reduce machining.
Wall thickness & minimums by process
Table B — Practical minimum wall thickness (indicative)
| Material & process | Green sand | No‑bake | Shell mold |
| Gray iron | 3–5 mm (0.12–0.20 in) | 3.5–6 mm (0.14–0.24 in) | 2.5–4 mm (0.10–0.16 in) |
| Ductile iron | 4–6 mm (0.16–0.24 in) | 5–7 mm (0.20–0.28 in) | 3–5 mm (0.12–0.20 in) |
| ADI (post‑cast) | +1–2 mm vs ductile | +1–2 mm vs ductile | +1 mm vs ductile |
| High‑Cr white iron | ≥10–12 mm (≥0.39–0.47 in) | ≥10–12 mm | ≥8–10 mm |
ADI requires enough sections for austempering to reach target hardness/toughness uniformly.
Tolerances, surface finish & machining stock
Table C — Capability by process (ISO 8062 & Ra)
- Wear parts: usually as‑cast functional surfaces, minimal machining; specify hardness range & microstructure, not tight CT grades.
- Housings: tighter GD&T on datums/bores; specify leak‑test and NDT levels.
| Process | ISO 8062‑3 CT grade | 100 mm linear tol (indicative) | Surface finish Ra | Typical machining stock |
| Green sand | CT9–CT10 | ±1.6–2.4 mm (±0.063–0.094 in) | 6.3–12.5 μm (250–500 μin) | 1.5–3.0 mm (0.06–0.12 in) |
| No‑bake | CT8–CT9 | ±1.2–1.8 mm (±0.047–0.071 in) | 3.2–6.3 μm (125–250 μin) | 1.2–2.5 mm (0.05–0.10 in) |
| Shell mold | CT6–CT7 | ±0.6–1.0 mm (±0.024–0.039 in) | 1.6–3.2 μm (63–125 μin) | 0.8–1.5 mm (0.03–0.06 in) |
Quality & testing plans (what to specify)
Wear parts
- Hardness mapping (HRC or HBW per zone); microstructure checks (carbides in white iron; ausferrite in ADI).
- Abrasion test (optional): report ASTM G65 Procedure A/B volume loss for development.
- Dimensional per ISO 8062 drawing; visual with acceptance samples.
Structural housings
- Material certificates: chemistry (OES), hardness HBW, tensile (ASTM A536 for ductile / A48 for gray).
- Dimensional: CMM on critical features; leak test for fluid circuits (e.g., 0.8–1.5 bar / 11.6–21.8 psi, 30–60 s).
- NDT as needed: RT/UT on hot‑spot regions; DPI/MPI for surface cracks.
- PPAP/FAI package with control plan, PFMEA, MSA where required.
Cost & sourcing tips
- Choose material to duty cycle: ADI often replaces high‑alloy steels at lower cost; white iron saves life in extreme grit but adds brittleness—use bimetal where impact exists.
- Simplify cores to lift yield; add radii to reduce feeders.
- Batch sizes at 50/100/200 pcs unlock setup amortization.
- Source with a Suzhou, China, foundry for green/no‑bake/shell under one roof + machining.
FAQs
Ready to Start Your Iron Casting Project With YBmetal?
YB Metal (Suzhou, China) supplies wear parts and structural housings for agricultural OEMs. We combine solidification simulation, heat‑treat control (ADI), and documented testing to meet field life and assembly precision.