UNDERSTANDING THE PROBLEM
Phase 0 — What does a solar cable factory actually do?
Before writing a single line of code, 7 months were spent understanding the domain. This document describes what a solar cable factory does — the machines, the materials, the flow, and the hundreds of design variations that make cable manufacturing far more complex than it appears. Every decision in the ERP system traces back to something in this document.
TABLE OF CONTENTS
1. THE COMPANY
Solen Kablo manufactures solar cables — primarily the H1Z2Z2-K standard used in photovoltaic installations worldwide. The cables are TUV Rheinland certified, use electron beam (E-beam) cross-linked insulation, and range from 1.5mm² to 240mm² cross-section.
What makes cable manufacturing deceptively complex is that every cable design has a unique production recipe. A 6mm² solar cable and a 35mm² solar cable may look similar, but they require completely different machine configurations, material quantities, intermediate products, and process parameters at every step.
Key insight: An ERP system for a cable factory cannot be generic. Each production step transforms materials in ways that depend on the specific cable design being produced. The number of input baskets, wire diameter, strand count, insulation thickness, radiation dose — everything varies by design.
2. THE PRODUCTION FLOW — OVERVIEW
From raw copper to shipped cable, the production passes through 8 distinct steps. Each step has its own machine, its own operators, its own constraints, and its own quality requirements.
Kabatel Çekme
Kalaylama
İncetel Çekme
Buncher
Ekstrüder
optional
Aktarma
SHIPMENT
Critical transition at Step 3: Steps 1–2 are simple — 1 basket in, 1 basket out. Starting from Step 3 (Fine Drawing), the input/output relationship becomes many-to-one and highly design-dependent. This is where the complexity explodes and where a manual tracking system breaks down.
3. THE PRODUCTION STEPS — IN DETAIL
The following uses a 6mm² solar cable as a running example to show concrete numbers. Every number changes for different cable designs.
Kabatel Çekme
Raw copper arrives as filmaşin — 8mm diameter copper rod, the universal starting material for wire manufacturing. The wire drawing machine pulls this rod through a series of progressively smaller dies, reducing the diameter.
Ø 8mm rod
Ø ~2.0mm or 1.8mm
Baskets: 800–1,100 kg each
The output diameter does not vary significantly between cable designs. The machine reduces 8mm down to roughly 2mm regardless of what the copper will eventually become.
Kalaylama
Bare copper wire is passed through a molten tin bath, depositing approximately 4μm of tin coating. Tinning provides corrosion resistance — critical for solar cables that are exposed to outdoor conditions for 25+ years.
Baskets: 800–1,100 kg
~4μm tin coating
Baskets: 800–1,100 kg
Like wire drawing, this is a relatively straightforward 1-basket-in → 1-basket-out process. The tin thickness is generally constant (~4μm) regardless of cable design.
İncetel Çekme
This is where everything changes. The tinned copper must be drawn down to the exact wire diameter specified by the cable design. And the output is no longer a single wire — the machine takes multiple input baskets and produces a single reel of multiple parallel wires.
Complexity explosion: Before this step, every process was 1-in → 1-out. From here on, the input/output relationship is many-to-one and entirely dependent on the cable design being produced.
Example: 6mm² Cable
A 6mm² cable requires a conductor made of 73 individual wires, each Ø 0.30mm. This cannot be produced in a single step. Two parallel fine drawing operations are needed:
MACHINE A — First Run
- Input:
- 10 baskets of tinned copper
- Output:
- 1 reel — 10 × Ø0.30mm
- Wire count:
- 10 parallel wires
MACHINE B — Second Run (parallel)
- Input:
- 11 baskets of tinned copper
- Output:
- 1 reel — 11 × Ø0.30mm
- Wire count:
- 11 parallel wires
The factory has 2 fine drawing machines, so these operations can run in parallel. The machine can accept 1–16 baskets as input and produce 1 reel with wire diameter ranging from 0.15mm to 0.65mm.
(design-dependent)
(N) × Ø(0.15–0.65mm)
N = number of input baskets
For 6mm²: after this step we have 2 reels — one with 10×0.30mm and one with 11×0.30mm. Together they hold all 21 baskets worth of tinned copper needed for the final conductor.
Buncher
The reels from fine drawing are combined. The buncher takes multiple reels, twists the wires together, and produces a single reel of stranded conductor (bükülü bakır).
Example: 6mm² Cable
The buncher needs all the fine-drawn wires to create the 73-wire conductor:
- 3 reels of 11 × Ø0.30mm = 33 wires
- 4 reels of 10 × Ø0.30mm = 40 wires
- Total: 7 input reels → 73 × Ø0.30mm = bükülü bakır
(design-dependent)
Bükülü bakır
(e.g. 73 × Ø0.30mm for 6mm²)
Multiple passes for large cables: The buncher can handle a maximum of 7 input reels. For larger cables (e.g. 120mm², 240mm²), the output of the first buncher pass becomes the input for a second pass. The machine limit is a hard physical constraint that shapes the entire production planning logic.
Ekstrüder
This is where wire becomes cable. The extruder applies plastic insulation (and optionally sheath) around the stranded conductor. The conductor passes through a crosshead die while molten plastic compound is pressed around it.
The extrusion step has the highest number of variables of any step in the factory:
- Insulation material: different compounds for E-beam vs. standard cables
- Sheath material: may be applied simultaneously or in a separate pass
- Dye/colorant: some E-beam plastics arrive pre-dyed, others need coloring
- Catalyst: E-beam cables do not require catalyst in the plastic compound
- Thickness: varies by cable design and standard requirements
- Dual extrusion: insulation and sheath can be applied in a single pass or separately
+ plastic compound(s)
+ optional dye, catalyst
(insulated wire / finished cable)
From this point forward, the product is on production reels (large, heavy reels used on the factory floor) rather than baskets.
E-Beam Işınlama
For E-beam cable designs, the extruded cable is passed under an electron beam accelerator. The radiation cross-links the polymer chains in the insulation, dramatically improving heat resistance, mechanical strength, and chemical resistance.
The radiation dosage is determined by the insulation material and thickness:
Not all cables go through E-beam. Standard PVC cables skip this step entirely. The ERP system must handle both flows.
Aktarma
The large production reels from extrusion (or E-beam) contain far more cable than any single customer order. The transfer step rewinds cable from the production reel into customer-specified lengths on smaller reels or coils (kangal).
(thousands of meters)
100m to 5,000m each
(per customer specification)
This is the first step where one input produces multiple outputs. A single production reel might be split across several customer orders with different length requirements.
Paketleme & Sevkiyat
Customer reels and coils are labeled, wrapped, palletized, and prepared for shipping. Documentation is generated — test certificates, conformity declarations, packing lists.
4. RAW MATERIALS
Before production can begin, raw materials must be received, inspected, tracked, and allocated. Every material enters the system with a QR code, a lot number, a measured weight, and delivery documentation.
COPPER (Bakır)
- Input form:
- 8mm filmaşin
- Unit:
- kg (weighed at entry)
- QR prefix:
- CU-
TIN (Kalay)
- Coating:
- ~4μm standard
- Factor:
- 0.7% of copper weight
- QR prefix:
- SN-
PLASTIC COMPOUNDS (Plastik)
- Types:
- PVC, XLPE, PE, HFFR
- Calc:
- volume × density
- Overfill:
- +14% on first layer
ADDITIVES
- Catalyst:
- % of plastic weight
- Dye:
- % of plastic weight
- Antirodent:
- sheath only, % ratio
REELS & PALETTES (Makara & Palet)
- Reel sizes:
- multiple standard sizes
- Kangal:
- reel_id = 0 (no reel)
- Range:
- 100m to 5,000m per unit
Material status lifecycle: Received → Approved → In Use → Consumed (or Rejected). Every status transition is tracked. remaining_weight decreases as material is consumed in production. When a copper basket enters a machine, its weight deduction is calculated from the cable design's material requirements.
5. THE HIDDEN MATH
Behind every production order is a material calculator that walks through the entire production flow and computes exact material requirements. These are not approximations — they are derived from laboratory-verified production constants.
Wire Weights (Verified Production Data)
Tinned wire weight in grams per meter, measured for every 0.01mm increment from Ø0.20mm to Ø0.60mm:
| Diameter | g/m | Diameter | g/m | Diameter | g/m |
|---|---|---|---|---|---|
| Ø0.20mm | 0.2818 | Ø0.30mm | 0.634 | Ø0.40mm | 1.1271 |
| Ø0.21mm | 0.3107 | Ø0.31mm | 0.677 | Ø0.45mm | 1.4272 |
| Ø0.25mm | 0.4403 | Ø0.35mm | 0.8629 | Ø0.50mm | 1.7635 |
| Ø0.28mm | 0.5523 | Ø0.38mm | 1.0172 | Ø0.60mm | 2.5452 |
Bundle Diameters (Microscope Measurements)
Actual bundle diameters measured from production cross-sections:
| Cable | Wire Count | Wire Ø | Bundle Ø | Structure |
|---|---|---|---|---|
| 4mm² | 50 | 0.30mm | 2.39mm | 5×(10×0.30) |
| 6mm² | 73 | 0.30mm | 2.89mm | 4×(10×0.30) + 3×(11×0.30) |
| 10mm² | 73 | 0.40mm | 3.86mm | 4×(10×0.40) + 3×(11×0.40) |
| 16mm² | 115 | 0.40mm | 4.84mm | 7×(13×0.40) + 2×(12×0.40) |
Production Constants
Buncher twist factor (1.001955): When wires are bunched, they follow a helical path — the actual wire length is ~0.2% longer than the cable length. This compounds: for two bunching stages (e.g. 95mm²), factor = 1.001955² = 1.003914. Ignoring this means ordering too little copper.
First layer overfill (+14%): When plastic is extruded directly onto bunched copper, extra material fills the valleys between outer wires (bumpy surface). Subsequent layers on smooth insulation don't need this. Discovered via microscope cross-section analysis.
6. STANDARDS, TESTING & QUALITY CONTROL
Solar cables must comply with international standards. Quality control is not a final inspection — it is woven into every production step.
Standard Categories
EN 50618, IEC 60228
UL 4703, UL 854
Company-specific tests
Test Categories
| Category | Test (TR) | Test (EN) | Standard | Unit |
|---|---|---|---|---|
| ELECTRICAL | ||||
| Maksimum İletken Direnci | Maximum Conductor Resistance | IEC 60228 | ohm/km | |
| Gerilim Deneyi | Voltage Test | EN 50618 | kV | |
| İzolasyon Direnci | Insulation Resistance | EN 50618 | Ω | |
| Kısmi Boşalma | Partial Discharge | EN 50618 | pC | |
| MECHANICAL | ||||
| Çekme Dayanımı | Tensile Strength | EN 50618 | N/mm² | |
| Kopma Uzaması | Elongation at Break | EN 50618 | % | |
| Sıcak Set Deneyi | Hot Set Test | EN 50618 | % | |
| Soğuk Büküm | Cold Bend | EN 60811-504 | — | |
| Soğukta Darbe | Cold Impact | EN 60811-506 | — | |
| DIMENSIONAL | ||||
| İzolasyon Kalınlığı | Insulation Thickness | EN 50618 | mm | |
| Kılıf Kalınlığı | Sheath Thickness | EN 50618 | mm | |
| İletken Çapı | Conductor Diameter | EN 50618 | mm | |
| Dış Çap | Outer Diameter | EN 50618 | mm | |
| CHEMICAL / ENVIRONMENTAL | ||||
| Yanma Deneyi | Flame Test | — | — | |
| UV Dayanım | UV Resistance | — | — | |
| Termal Yaşlandırma | Thermal Aging | — | — | |
| Duman Yoğunluğu | Smoke Density | — | — | |
Test Frequency
Tests are not run once — they are triggered at specific points during production:
- Üretim başı (Production start) — Lab alerted when machine starts
- Üretim sonu (Production end) — Lab alerted when production completes
- Her ikisi (Both) — Start and end
- Her makara sonu (Each reel end) — For continuous monitoring
Tests are embedded in the cable design itself. When a design is created, the engineer selects which tests apply to each production step and at what frequency. When production starts, the system automatically alerts the laboratory. Test results are linked to specific production sessions and batch codes for full traceability.
7. CABLE MARKING
Every meter of cable is printed with identification markings during extrusion. The marking is a legal requirement — it identifies the manufacturer, standard, cable type, and production batch. A typical marking sequence:
SOLEN BEAM • TUV RHEINLAND • EN 50618 • H1Z2Z2-K • 1×6mm² • 1,5 kV DC • HALOGEN FREE LOW SMOKE • MADE IN TURKEY • <CE> • Dca • {ORDER_NO} • {METER} MT
Dynamic fields like {ORDER_NO} and {METER} are populated in real-time during production. The meter counter increments continuously as cable is extruded.
8. CABLE DESIGN NOTATION
Every cable design is encoded in a structure formula that describes its complete physical composition. This notation drives the entire production flow calculation.
Example: 6mm² E-beam Solar Cable
(4×(10×0.3mm) + 3×(11×0.3mm)) + INS_0.7mm_DYE + SHT_0.8mm_CAT_DYE
- 4×(10×0.3mm) — 4 groups of 10 wires at Ø0.30mm = 40 wires
- 3×(11×0.3mm) — 3 groups of 11 wires at Ø0.30mm = 33 wires
- Total: 73 wires → 73×0.30mm conductor
- INS_0.7mm_DYE — 0.7mm insulation with dye (no catalyst = E-beam cable)
- SHT_0.8mm_CAT_DYE — 0.8mm sheath with catalyst and dye
This notation is not just documentation — it is machine-readable. The ERP system parses it to generate the complete production flow, calculate material requirements, and create work cards for each machine.
Cable Types
| Type | Description | E-beam? | Frequency |
|---|---|---|---|
| Klasik Kablo | Standard cable with catalyst cross-linking | No | Common |
| E-beam Kablo | Electron beam cross-linked, no catalyst needed | Yes | Primary |
| Twin Cable | Dual conductor, special extruder head | Varies | ~1% of production |
Cable Colors
Siyah (Black) • Kırmızı (Red) • Beyaz (White) • Yeşil-Sarı (Green-Yellow) • Pembe (Pink) • Mavi (Blue)
9. HALF-PRODUCT TRACKING
Between raw material and finished cable, the factory floor is covered with half products (yarı mamul) — intermediate goods at various stages of completion. Each half product has a system-generated code that encodes its exact state.
Half Product Code System
| Code | Machine | Product | Example |
|---|---|---|---|
| A | Kabatel Çekme | Çıplak bakır (bare copper) | A-001 |
| X | Kabatel output → Kalaylama input | Drawn wire ready for tinning | X-001 |
| Y | Kalaylama | Kalaylı bakır (tinned copper) | Y-001 |
| Z, T, U | İncetel Çekme | Fine-drawn wire reels | Z-001 |
| T, Z | Buncher | Bükülü bakır (stranded conductor) | T-002 |
Same code, different designs: A half product with the same physical properties (e.g. 10×0.30mm fine-drawn reel) gets the same system code regardless of which cable design it was originally produced for. This enables stock sharing — if a half product from one order matches the spec of another order, it can be reused. The system uses a SHA256 hash of the specifications to ensure deterministic code assignment.
10. WHY THIS IS AN ERP PROBLEM
A cable factory looks simple from the outside: copper goes in, cable comes out. But the production flow has several properties that make manual tracking impossible at scale:
- Fan-in / fan-out: Steps 3–4 take many inputs to produce one output. Step 7 takes one input and produces many outputs. Tracking material flow requires understanding these relationships per design.
- Design-dependent everything: The number of input baskets, wire diameter, strand count, number of buncher passes, insulation material, radiation dose — all vary by cable design. There is no single "recipe."
- Intermediate products: The factory floor simultaneously contains raw copper, bare copper, tinned copper, fine-drawn reels, stranded conductors, insulated cables, and finished products. Each has its own identity and location.
- Parallel processing: Multiple machines can run simultaneously on different parts of the same order. Two fine drawing machines can work in parallel; different designs can share machine time.
- Quality at every step: Each intermediate product can be tested. Lab results must be linked to specific production batches for traceability and certification.
The real problem is not software — it's domain knowledge. Any developer can build CRUD screens. But knowing that a 6mm² cable needs exactly 73 wires at 0.30mm, distributed as 3×11 + 4×10 across two fine drawing machines, feeding into a single buncher — that knowledge took 7 months of being on the factory floor, watching machines, talking to operators, and making mistakes.
This document is an extremely condensed summary. Every step, every decision, every action has unseen, tiny, extremely important details that cannot be captured in a single page. This is the map — not the territory.