Thin-shell Investment Casting (Lost Wax Casting) is highly regarded for its superior precision ($\pm$0.05–0.1 mm), smooth surface finish ($Ra \leq 3.2$ µm), and the ability to cast complex geometries with minimal machining. However, without optimization, production costs can escalate by 20–30% due to high scrap rates, long cycle times, and material waste.
At CDL LOST WAX CASTING JOINT STOCK COMPANY (Dong Nai) – an ISO 9001:2015 certified facility (issued March 13, 2025; valid until March 12, 2028) with a 60-ton/month capacity and a 10,000 $m^2$ plant – we have implemented quality management systems that reduced production costs by 15–25% and boosted productivity by 30% within 18 months.
This article analyzes cost structures, 6 practical optimization solutions (verified by CDL data), and the application of ISO 9001:2015 for continuous improvement.
1. Cost Structure Analysis in Lost Wax Casting
The typical production cost per ton (pre-optimization data at CDL) is allocated as follows:
- Raw Materials (Wax + Slurry + Metal): 45–50%
- Energy (Burnout furnaces, induction furnaces, injection machines): 18–22%
- Labor: 15–18%
- Equipment & Maintenance: 8–10%
- Scrap & Recycling: 5–8%
- Others (Inspection, internal logistics): 4–6%
Key improvements: Before ISO implementation, the average scrap rate was 8–12%, slurry dipping cycles took 48–72 hours, and wax reuse was only 75–80%. Post-optimization: scrap rate <3%, dipping cycle 24–36 hours, and wax reuse 95–98%.
2. 6 Practical Solutions for Cost & Productivity Optimization
- Solution 1: 95–98% Wax Reclamation (Saving 12–15% in material costs)
- Dewaxing using steam autoclaves at 150–180°C and 6–8 bar for 15–18 minutes.
- Reclaimed wax is filtered, purified, and fed back into injection machines.
- Result: Only 20–50 kg of virgin wax replenishment needed per month for every ton used.
- Solution 2: Slurry Dipping Optimization (Reducing time by 40–50%)
- Refining shell layers from 15–18 down to an optimal 12–15 layers (9–11 mm shell thickness).
- Using automated dipping and sanding systems with humidity-controlled drying (50–55% RH).
- Result: Shell building time dropped from 48–72h to 24–36h, increasing productivity by 35%.
- Solution 3: Automated Shot Blasting & Shell Removal (Reducing labor by 50%)
- Deploying vertical and horizontal automated shot blasting (4–6 bar, 0.6–0.8 mm steel grit).
- Replacing manual labor with pneumatic hammers and vibratory de-shelling machines.
- Result: Processing time per unit dropped from 45 mins to 8–12 mins.
- Solution 4: Metal Scrap Recovery & Recycling (Saving 7–9%)
- Crushing and screening ceramic waste; 100% remelting of risers and gates.
- Result: Achieving 92–95% metal recovery rate.
- Solution 5: ISO 9001:2015 Quality Control (Scrap rate <3%)
- 100% wax pattern inspection (3D measurement).
- Spectrometer analysis of chemical composition before every heat/pour.
- Real-time logging of burnout and pouring temperatures ($\pm$5°C).
- Final NDT: CMM, Dye Penetrant, and mechanical property testing.
- Solution 6: Gating System Optimization & Simulation (Saving 10–12% in supplies)
- Using ProCAST/Moldflow to design optimal “wax trees” (reducing riser count and gate size).
- Result: A 500 kg batch now requires only 420–450 kg of raw material instead of 550 kg.
3. Comparative Data (CDL Factory – 1 Ton of Stainless Steel)
| Category | Pre-Optimization | Post-Optimization (2025–2026) | Savings (%) |
| Scrap Rate | 10–12% | <3% | 75% |
| Wax Reuse | 75–80% | 95–98% | 20% |
| Dipping Cycle | 48–72 hours | 24–36 hours | 45% |
| Labor (De-shelling) | 45 mins/unit | 10 mins/unit | 78% |
| Energy Costs | 100% | 82% | 18% |
| Total Cost/Ton | 145–160M VND | 110–125M VND | 22–25% |
4. Business Benefits & Recommendations
- Price Reduction: 15–22% lower costs, boosting export competitiveness.
- Lead Time: Reduced from 21 days to 12–14 days.
- Market Reach: Successfully serving major partners like THACO, Yamaha, Hyundai, and Ford.
Recommendations for Enterprises:
- Conduct a process audit (1–2 weeks).
- Invest in casting simulation and automated dipping/blasting (ROI within 8–12 months).
- Implement ISO 9001:2015 as the control foundation.
Conclusion
Optimizing Investment Casting is not about cutting corners—it is about intelligent control of every millimeter, every degree Celsius, and every gram of material. With ISO 9001:2015 and our proven solutions at Lostwaxcasting CDL, we turn operational costs into a sustainable competitive advantage.
