In steel casting foundries, riser removal is one of the most time-consuming and costly post-casting processes. After molten metal solidifies in the mold, the risers and pads that prevented shrinkage defects must be cut away from the finished casting—a task that directly impacts both productivity and operational costs.
For foundry managers and production engineers facing this daily challenge, one critical question emerges: Which cutting method delivers the fastest, most cost-effective riser removal?
In this comprehensive study for this week's blog, we will compare two widely-used industrial cutting methods—Arc-Air and Thermal Lance—to determine the optimal solution for removing large stainless steel risers.
Testing Method and Evaluation Criteria for Riser Removal
Testing Objectives: Understanding Riser Cutting Practices
This comprehensive study evaluates riser removal methods used across 23 steel foundries in Mexico. The test focused on understanding current riser cutting practices, technology adoption rates for thermal lance and arc-air systems, and the operational challenges foundries face when removing large stainless steel risers from castings.
Performance Evaluation Criteria for Cutting Stainless Steel Risers
We will evaluate both methods across 4 critical performance factors:
- Cutting time (direct productivity impact)
- Required equipment (initial capital investment)
- Consumables (ongoing operational costs)
- Total cost analysis (complete economic comparison)
Stainless Steel Riser Cutting Method 1: Using Arc Air
What Is Arc-Air?
Arc-Air is a cutting process that uses an electric arc between a metal workpiece and a non-consumable carbon electrode to melt the metal, creating a cut or removing material. Simultaneously, a directed stream of compressed air blows away the molten metal produced by the electric arc, effectively removing it from the cutting zone.
Important Note for Stainless Steel: Due to the nature of this process, cutting creates a thin carbon deposit layer on the cut surface. When Arc-Air is used on stainless steel, this residual carbon layer must be removed through grinding or wire brushing. This step is critical to restore the corrosion resistance of stainless steel and ensure proper weld quality if subsequent welding is required.
Arc-Air Applications
Arc-Air cutting is a versatile method that can be used effectively on all types of metals and alloys.
Arc-Air Equipment & Consumables
To apply the Arc-Air cutting method, the following equipment and consumables are required:
Equipment:
- Welding machine
- Air compressor
- Manual torch, cables, and holders
- Safety equipment
Consumables:
- Carbon rods (electrodes) — Available in various diameters
- Electricity - required to operate Arc-Air
Stainless Steel Riser Cutting Method 2: Using Thermal Lance
What Is Thermal Lance?
Thermal lance (also called burning bar or oxygen lance) is an exothermic cutting tool that operates through pure chemical combustion—no electricity required. It consists of a steel tube filled with steel wires that burn in high-pressure oxygen to generate extreme temperatures of 3,600°C, capable of cutting through virtually any material regardless of hardness or alloy composition.
Thermal Lance Applications
Thermal lance is particularly effective for applications that require high temperature to overcome their resistance to cutting and melting point.
Thermal Lance Equipment & Consumables
To apply the thermal lance cutting method, the following equipment and consumables are required:
Equipment
- Lance holder
- Oxygen cylinder or oxygen source
- Oxygen regulator and flowmeter
- High-pressure oxygen hose
- Backfire system — MANDATORY safety device prevents flame backflow into oxygen system
- Oxy-acetylene torch
- Safety equipment (PPE)
Consumables
- Thermal lance pipes — Available in various diameters
- Oxygen — Primary consumable
- Ignition gases (oxy-acetylene) — Minimal consumption, only for initial preheat
Arc-Air vs Thermal Lance: Performance Comparison for Cutting Stainless Steel Risers
We conducted a comparative cutting study in Mexico to evaluate the time and cost required for removing large stainless steel risers from castings. A test casting was produced with a 16" × 16" stainless steel riser specifically for this investigation. Both arc-air and thermal lance methods were employed to remove identical risers, and performance metrics including cutting time and total cost were systematically measured and compared. The image below illustrates the test casting configuration and the 16" × 16" riser used throughout this study.
Equipment and consumable cost calculations are detailed in the table below.
Equipment Requirements
| Equipment | Thermal Lance | Arc-Air |
| Power Source | No electrical power needed | 2× welding machines (series) |
| Compressed Air | Not required | Air compressor required |
| Oxygen System | Oxygen cylinders + regulator | Not required |
| Energy Cost | $0 (no electricity) | High (dual machines + compressor) |
Consumables Pricing
| Cost Item | Thermal Lance | Arc-Air |
| Primary Consumables | Thermal lance (*) | Carbon electrodes (*) |
| Oxygen Supply | $24.91 per full cylinder | Not required |
| Electricity (Welding) | Not required | $0.05 per kWh (2 machines in series) |
| Electricity (Compressor) | Not required | $0.05 per kWh |
| Labor Rate (in Mexico) | $22.23 per hour | $22.23 per hour |
(*) Detailed consumable pricing and complete cost analysis are provided on a per-inquiry basis to ensure accuracy for your specific application. To obtain detailed pricing information, please contact our sales team at sales.dept@daiwalance.com.vn or click the link below.
Based on the unit pricing table provided above, the time consumed and total operating cost to cut one 16" × 16" stainless steel riser using each method is calculated as follows:
| Method | Time Consumed (hours) | Total Operating Cost (USD) |
| Arc-Air | 2.25 | $31.92 |
| Thermal Lance | 0.33 | $43.65 |
Key Performance Comparison
When comparing the two primary performance variables—total cost and cutting time—the results reveal significant differences
| Cutting Time (hours) | Total Operating Cost (USD) | |
| Result |
|
|
| Evaluation |
Thermal lance delivers exceptional cutting speed performance on stainless steel risers, completing cuts in just 20 minutes compared to Arc-Air's 135 minutes. This represents an 85% reduction in cutting time and translates to a 7× increase in daily throughput. |
The total operating cost for thermal lance cutting (including thermal lance consumables, oxygen supply, and labor) is 37% higher than Arc-Air (including carbon electrodes, electrical power for dual welding machines and compressor, and labor). However, in high-wage labor markets, when hourly labor rates are higher, thermal lance can become economically advantageous. |
Conclusion
First and foremost, we would like to express our sincere gratitude to our partners at Mexico for their invaluable support in making this comparative study possible. Their willingness to provide access to production facilities, conduct controlled cutting tests, and share operational data was instrumental in generating the real-world performance metrics that form the foundation of this research.
We hope that the findings presented in this study will serve the foundry community by providing the data-driven decision framework that has been notably absent in the industry—helping foundry managers and production engineers optimize their riser removal operations based on their specific economic contexts rather than assumptions or incomplete information.
By now, we think that you probably have a clearer understanding of the differences in cutting time, costs, and essential equipment requirements for cutting stainless steel risers using two proven industrial methods: Arc-Air and Thermal Lance.
So, which method cuts stainless steel risers better?
The answer is: it depends—because the optimal choice depends on what you prioritize: time savings, labor efficiency, equipment investment, consumables, or total cost.
Most foundries initially focus solely on price. However, time is equally critical in manufacturing operations. Ultimately, production success means optimizing time—producing the maximum number of castings with optimal time, optimal labor, and optimal equipment utilization.
But if you're not sure which method suits your operation most?
Contact our experienced team at Daiwa Lance for personalized sharings and recommendations. Based on your specific technical requirements, existing equipment, and operational priorities, we'll recommend the most cost-effective solution that delivers the performance you need.
Click the link below to connect with Daiwa Lance's engineering team.
