Robot Frame Manufacturing
TL;DR
- Purpose: Structural frames for robots
- Material: Hybrid Fe/Al (steel + aluminum)
- Technology: WAAM 3D printing + abrasive grinding
- Output: ~5 frames/day
Overview
The robot frame is the structural chassis to which all other components attach: batteries, actuators, electronics. The frame must be strong (Fe) and lightweight (Al).
Frame Material Balance
| Robot Type | Frame Mass | Fe | Al | Other* | Ratio |
|---|---|---|---|---|---|
| Mole-M | ~1250 kg | 1040 kg | 210 kg | — | 83% Fe / 17% Al |
| Crab-M | ~800 kg | 280 kg | 360 kg | 160 kg | 35% Fe / 45% Al / 20% |
| Centaur-M | ~320 kg | 70 kg | 200 kg | 50 kg | 22% Fe / 62% Al / 16% |
*Other: fasteners, wiring channels, fiberglass panels.
Distribution Principle: - Mole-M: Heavy work (digging) → more steel - Crab-M: Medium load (transport) → Fe/Al balance - Centaur-M: Precision work (manipulation) → more aluminum (lightweight)
Frame Production: WAAM 3D Printing
Process
| Step | Description |
|---|---|
| 1. 3D Model Development | CAD model of frame (custom for each type) |
| 2. WAAM Printing | Robot manipulator deposits wire layer by layer |
| 3. Grinding | Abrasive processing of mounting surfaces |
| 4. Heat Treatment | Stress relief: annealing 550-650°C, 1-2 hr/25 mm, in vacuum (natural) |
| 5. Quality Control | Ultrasonic testing for cracks, geometry measurement |
Details: [WAAM](../../reference/technology-readiness.qmd#waam-3d-printing) 3D Printing
WAAM Cell for Frames
| Parameter | Value |
|---|---|
| Type | 6-axis robot manipulator |
| Wire | Fe dia. 1.6-2.0 mm + Al dia. 1.6 mm |
| Throughput | 25-35 kg/hr (multi-wire system) |
| Shielding | FCAW-S (self-shielded flux) |
Frame Print Time
| Robot Type | Frame Mass | WAAM Time | Grinding Time | TOTAL |
|---|---|---|---|---|
| Mole-M | 1250 kg | 40 hours | 8 hours | ~48 hours |
| Crab-M | 800 kg | 25 hours | 5 hours | ~30 hours |
| Centaur-M | 320 kg | 10 hours | 2 hours | ~12 hours |
With 3 WAAM cells: Can print 3 frames in parallel → ~5 frames/day (mixed types).
Grinding of Mounting Surfaces
After WAAM printing, the frame has a rough surface. Critical areas are processed by abrasive grinding.
| Operation | Tool | Precision |
|---|---|---|
| Grinding mounting surfaces | Al₂O₃ abrasive wheel | +/-0.1 mm |
| Drilling holes | Drill bit (Centaur-M robot) | +/-0.2 mm |
| Threading | Tap (Centaur-M robot) | M6-M20 |
Advantages of abrasive grinding: - No imported high-speed spindle required - Al₂O₃ (corundum) produced from regolith — unlimited supply - Same Centaur-M robot as for WAAM
Mounting points per frame: - Mole-M: ~50 (actuators, battery, electronics) - Crab-M: ~40 - Centaur-M: ~30
Hybrid Fe/Al Construction
Question: How to combine steel and aluminum in one frame?
Answer: Two approaches:
Option A: Sequential Printing
- Print steel frame (WAAM Fe)
- Print aluminum overlays on steel (WAAM Al)
- Strength provided by mechanical interlocking of layers
Problem: Different thermal expansion coefficients (Fe vs Al) → cracks during thermal cycling.
Option B: Modular Construction (recommended)
- Print steel skeleton (load-bearing elements)
- Print aluminum panels (housing, radiators)
- Assembly with bolts/rivets
Advantages: - No thermal expansion issues - Easy replacement of damaged panels - Clear separation of functions (steel = strength, aluminum = lightweight)
Material Balance
For 5 frames/day (average mix):
| Material | Mass for 5 frames | Source |
|---|---|---|
| Iron (Fe) | ~2.5 t | Regolith Processing |
| Aluminum (Al) | ~1.2 t | Regolith Processing |
Consumption from daily production: - Fe: 2.5 t from 11 t/day = 23% - Al: 1.2 t from 42 t/day = 3%
Quality Control
| Parameter | Method | Standard | Action |
|---|---|---|---|
| Porosity | In-process WAAM monitoring | <2% | Parameter correction |
| Geometry | Touch probe | +/-1 mm | Grinding rework |
| Cracks | Visual (Centaur-M cameras) | No visible defects | Reject |
| Strength | Load test (sampling) | Per specification | — |
Power Consumption
| Component | Power |
|---|---|
| WAAM cells (3 units) | 30 kW |
| Grinding cells (2 units) | 10 kW |
| Heat treatment | 20 kW |
| TOTAL | ~60 kW |
Equipment Maintenance
| Operation | Frequency | Performer |
|---|---|---|
| WAAM torch replacement | 1 month | Centaur-M |
| Abrasive wheel replacement | 1 week | Centaur-M |
| Robot manipulator calibration | 1 month | Automatic |
| Rotary table cleaning | Daily | Crab-M |
Wiring: MI Cable
Internal robot wiring and 10 kV power cables (Mole-M, Centaur-M) use MI cable (Mineral Insulated) — MgO insulation in a metal sheath.
| Parameter | Value |
|---|---|
| Insulation | MgO (magnesium oxide) |
| Sheath | Stainless steel or Al |
| Temperature range | −200°C … +1000°C |
| All materials | Local (Mg, O, Fe/Al) |
Advantages on Mercury: MgO is hygroscopic — on Earth this is a problem (moisture reduces insulation resistance). In Mercury’s vacuum — an advantage: no moisture, insulation resistance is maximized.
MI cable assembly bench: 15 m², 500 kg. Output up to 1500 m/day. Part of the F-R dome Forming zone.
See Also
- WAAM 3D Printing — manufacturing technology
- Rolling Mill — wire production
- Mole-M Assembly — frame installation
- Crab-M Assembly — frame installation
- Centaur-M Assembly — frame installation