If you’re under pressure to lower total landed cost without risking quality, start by re‑engineering the aluminum sand casting package: geometry, cores, gating/risers and machining. Below is a concise playbook our Poznań team uses to remove waste before it ever reaches the shop floor.
1) Know Your Cost Stack
Tooling/patterns (pattern material, core boxes, durability).
Molding route (green sand vs no‑bake), flask size, man‑hours.
Cores (quantity, complexity, assembly time, yield loss).
Metal (alloy price, returns/scrap/re‑melt).
Yield (gating/risers vs net part weight).
Quality (scrap/rework from casting defects like shrinkage or porosity).
CNC/finishing (time, burr control, tool wear).
Logistics (packaging, handling heavy parts).
2) Quick‑Win DFM Moves
Parting line first: pick the simplest parting to minimize cores and undercuts.
Draft everywhere: generous, consistent draft avoids torn surfaces and rework.
Uniform sections: ribs/gussets over pads; remove isolated mass that breeds hot spots.
Radii & blends: eliminate knife edges and stress risers.
Self‑locating features: boss/pad strategy that simplifies fixturing and reduces CNC time.
3) Core Economics (Spend Less by Designing for Fewer/Smarter Cores)
Challenge every core: can a local machining op replace it?
Combine multiple small cores into one stable core with better prints and venting.
Add core prints sized for rigidity; design clearance for assembly and shakeout.
Use casting simulation to validate venting and predict gas paths.
4) Raise Yield with Simulation‑Led Gating & Risers
Model fill + solidification to place gates, filters, risers and chills.
Optimize runner size and overflow positions to reduce turbulence and keep oxides out of the casting.
Target a balanced yield—don’t chase extreme yield at the expense of defect risk.
5) Alloy & Melt Discipline (Cheap Insurance Against Scrap)
Select aluminum (Al‑Si/Al‑Mg), bronze or brass based on strength/corrosion vs machinability and finish.
Control melt chemistry/temperature; skim effectively; maintain sand moisture/binder ratios (for green/no‑bake).
For seal‑critical components, plan for impregnation as an interim safety net while the process centers.
6) Tolerances, GD&T & Machining Allowances (Spend Where It Matters)
Set realistic ISO 8062 casting tolerances and layer GD&T for castings on datums/bores/lands.
Machine only the functional faces; machining allowances should be minimal but safe.
Align datum structure with the way the part will be fixtured—this shortens cycle time and prevents scrap from stack‑ups.
7) When Another Process Is Cheaper (Be Process‑Agnostic)
Gravity die casting (permanent mold casting): better as‑cast finish/stability at moderate sizes/volumes.
HPDC / aluminum die casting: high volumes, thin walls, small features—per‑piece price can beat sand after tooling amortization.
LPDC: laminar fill for structural integrity; consider for load‑bearing geometries.
Investment casting (lost‑wax): small, intricate shapes where cores would explode cost.
8) Case‑Style Example (Representative)
Part: Aluminum machinery cover, 18 kg, EAU 2,400.
Original issues: 5 cores; late‑fill shrinkage; heavy machining (3.2 mm stock) on two faces.
Actions: Re‑picked parting line; combined cores to 3 pieces; simulation‑driven riser/chill redesign; reduced machining stock to 1.2 mm with clearer datum scheme.
Outcome: Lower pattern cost on rev‑B, ~12–18% metal yield gain, CNC time down ~20%, scrap from shrinkage near 0 after redesign. (Representative of our methodology; figures indicative.)
9) Quality & Control Plan
PFMEA/Control Plan with checkpoints for sand properties, core bake, vent cleaning, pour temp and time.
CMM for FAI/PPAP; optional CT scanning per customer agreement.
Defined reaction plans for porosity/shrinkage excursions.
10) RFQ Handoff Checklist (Fastest Way to Save Money)
3D model with draft + wall consistency; 2D with ISO 8062 class and GD&T on CTQs.
Alloy, EAU, ramp curve; surface/finish expectations; NDT/leak‑test parameters.
Packaging & handling requirements for heavy parts; target palletization.
Request a casting simulation review to lock gates/risers/chills before pattern cut.
Takeaway: The cheapest sand casting is the one engineered to cast cleanly—fewer cores, smarter gating/risers, disciplined alloys/melt, realistic tolerances and targeted machining. Use simulation‑first DFM and a process‑agnostic mindset to reach the lowest sustainable TCO.