Rolling Mill

TL;DR

  • Purpose: Converting billets into sheets, profiles, wire
  • Equipment: 6-stand rolling mill + wire drawing machine
  • Throughput: 41 t Al + 10.7 t Fe-Mn steel → foil, sheets, wire, profiles
  • Output: 50 μm foil, 1-3 mm sheets, Ø1.6-2.0 mm wire

Overview

The rolling mill is key equipment for converting 100×100 mm billets into useful semi-finished products. Metal passes through a series of rolls, gradually decreasing in thickness.

Rolling Complex Diagram

flowchart TD
    subgraph INPUT["INPUT"]
        BILLETS_AL["Al Billets 41 t/day<br/>from CCM-Al"]
        BILLETS_FE["Fe-Mn Billets 10.7 t/day<br/>from CCM-Fe"]
    end

    subgraph HEATING["HEATING"]
        FURNACE_AL["Ind. Furnace Al<br/>400-500°C"]
        FURNACE_FE["Ind. Furnace Fe<br/>1100-1200°C"]
    end

    subgraph ROLLING["ROLLING"]
        MILL["6-Stand Mill<br/>100 mm → Ø20 mm"]
    end

    subgraph AL_FINISH["ALUMINUM"]
        FOIL["Foil Rolling<br/>→ 50 μm"]
        SHEET["Sheet Rolling<br/>→ 1-3 mm"]
        WIRE_AL["Al Wire Drawing<br/>→ Ø1.6 mm"]
    end

    subgraph FE_FINISH["Fe-Mn STEEL"]
        PROFILE["Profiles<br/>Ø20 mm"]
        WIRE_FE["Fe Wire Drawing<br/>→ Ø1.6-2.0 mm"]
    end

    BILLETS_AL --> FURNACE_AL
    BILLETS_FE --> FURNACE_FE
    FURNACE_AL --> MILL
    FURNACE_FE --> MILL
    MILL -->|"Al 60%"| FOIL
    MILL -->|"Al 30%"| SHEET
    MILL -->|"Al 10%"| WIRE_AL
    MILL -->|"Fe 60%"| PROFILE
    MILL -->|"Fe 40%"| WIRE_FE

    style INPUT fill:#f0e68c
    style HEATING fill:#fff3cd
    style ROLLING fill:#d4edda
    style AL_FINISH fill:#b8e0d2
    style FE_FINISH fill:#cce5ff

Heating Furnace

Before rolling, the billet must be heated to a plastic state.

Parameter Aluminum Iron
Temperature 400-500°C 1100-1200°C
Furnace Type Induction Induction
Atmosphere Nitrogen N₂ Nitrogen N₂
Heating Time 10-15 min 30-40 min
Power 200 kW 500 kW

Why induction furnace? - Rapid heating (no waiting for furnace warm-up) - Precise temperature control (±10°C) - No combustion products (clean environment) - ~90% efficiency

Nitrogen atmosphere: Prevents metal oxidation during heating.

Rolling Mill (6 Stands)

A series of rolls, each reducing the thickness of the workpiece.

Parameter Value
Number of Stands 6
Input 100×100 mm billet
Output Ø20 mm profile or 5 mm strip
Rolling Speed 1-3 m/s (increasing toward final stands)
Force per Stand 50-200 tons
Roll Material Hardened steel with Al₂O₃ coating

Stand Sequence

Stand Input Output Reduction
1 100×100 mm 80×80 mm 20%
2 80×80 mm 60×60 mm 25%
3 60×60 mm 40×40 mm 33%
4 40×40 mm Ø30 mm 30%
5 Ø30 mm Ø25 mm 20%
6 Ø25 mm Ø20 mm 20%

Roller table between stands: Metal cools by ~50-100°C between passes.

Finishing: Aluminum

After the 6-stand mill, aluminum splits into three streams.

1. Foil Rolling (60% of Al stream, ~25 t/day)

50 μm aluminum foil for mirrors.

Parameter Value
Input 5 mm strip
Output 50 μm foil
Number of Passes 8-10
Rolling Speed 10-20 m/min
Lubricant Mineral oil + graphite

Process: - 5 mm strip passes through a series of rolls with decreasing gap - Each pass reduces thickness by 30-40% - Final thickness: 50 μm (0.05 mm)

Quality Control: - Thickness: laser profilometer (±2 μm) - Flatness: IR camera (deviation <0.1 mm/m) - Cleanliness: optical inspection (no scratches)

Note: 50 μm is an intermediate semi-finished product. Swarm mirrors require 4 μm foil (see Mirrors). Finish rolling from 50 → 4 μm is performed on a dedicated foil mill (~8-10 additional passes at 30-40% reduction each). Industrial reference: Novelis/UACJ produce 4.5 μm foil commercially.

Application: Swarm Mirrors

2. Sheet Rolling (30% of Al stream, ~13 t/day)

1-3 mm aluminum sheets for robot housings.

Parameter Value
Input 5 mm strip or Ø20 mm profile
Output 1-3 mm sheets
Sheet Width 500-1000 mm
Rolling Speed 5-10 m/min

Sheet Cutting: - Gas cutting: 1×2 m sheets - Plasma cutting: complex contours (by templates)

Application: Robot Assembly, housings, radiators

3. Al Wire Drawing (10% of Al stream, ~4 t/day)

Ø1.6-2.0 mm wire for WAAM 3D printing.

Parameter Value
Input Ø20 mm profile
Output Ø1.6-2.0 mm wire
Number of Passes 11-15
Drawing Speed 5-10 m/s
Dies W (Bootstrap import) → Si₃N₄ (standard local, 3× lifespan)

Process: - Ø20 mm profile is pushed through dies with decreasing diameter - Each die reduces diameter by 15-20% - At 15-20% reduction per pass: Ø20 → Ø1.6 mm requires 11-15 dies - Final wire: Ø1.6-2.0 mm

Lubricant: MoS₂ (molybdenum disulfide) — works in vacuum

Winding: Wire is wound onto spools of 50-100 kg

Application: WAAM 3D Printing

Finishing: Fe-Mn Steel

After the 6-stand mill, Fe-Mn steel splits into two streams.

4. Profiles (60% of Fe stream, ~6.4 t/day)

Steel profiles Ø20 mm for frames and structures.

Parameter Value
Input Ø20 mm profile (after 6-stand mill)
Output 20×20 mm square / Ø20 mm round
Cut lengths 3-6 m
Cutting Gas / plasma

Process: - Profile from 6-stand mill already has final cross-section Ø20 mm - Straightening on roller straightener - Cutting to 3-6 m lengths - Marking and storage

Application: Robot frames, equipment structures, load-bearing elements

5. Fe Wire Drawing (40% of Fe stream, ~4.3 t/day)

Ø1.6-2.0 mm wire for WAAM 3D printing of steel parts.

Parameter Value
Input Ø20 mm profile
Output Ø1.6-2.0 mm wire
Number of Passes 11-15
Drawing Speed 3-5 m/s
Dies W (Bootstrap import) → Si₃N₄ (standard local, 3× lifespan)

Process: - Similar to aluminum wire drawing - Higher drawing force (steel is harder than Al) - Intermediate annealing after 4-5 passes (strain relief)

Lubricant: MoS₂ (molybdenum disulfide)

Winding: Spools of 50-100 kg

Application: WAAM 3D Printing of steel parts

Material Balance

Aluminum stream distribution (41 t/day):

Product Mass % Application
50 μm foil ~25 t 60% Mirrors
1-3 mm sheets ~13 t 30% Robots, housings
Ø1.6 mm wire ~4 t 10% WAAM

Fe-Mn steel stream distribution (10.7 t/day):

Product Mass % Application
Profile (square/round) ~6.4 t 60% Frames, structures
Ø1.6-2.0 mm wire ~4.3 t 40% WAAM

Power Consumption

Component Power Purpose
Induction Furnace (Al) 200 kW Heating Al to 500°C
Induction Furnace (Fe) 500 kW Heating Fe to 1200°C
6-Stand Mill 300 kW Rolling
Foil Rolling 100 kW Final foil rolling
Sheet Rolling 50 kW Sheet cutting
Wire Drawing Machine 150 kW Wire drawing
Roller Tables 30 kW Transport
Automation 10 kW Sensors, control
TOTAL ~1340 kW

Maintenance

Operation Frequency Executor
Roll Replacement 2-3 weeks Centaur-M (4 robots)
Die Replacement 1 month Centaur-M
Roller Table Cleaning Daily Crab-M
Sensor Calibration Weekly Automation
Equipment Lubrication Daily Automation (drip lubrication)

Roll replacement time: 4-6 hours (including cooling and disassembly).

See Also