Short answer: A complete purlin production line needs seven equipment groups in one sequence: hydraulic decoiler → leveler → hydraulic pre-punch → roll forming main unit → cut system → PLC control cabinet + HMI → run-out table. A mid-size CZ line typically processes 1–3.2 mm galvanized coil into C/Z purlins with webs of 80–300 mm, at 12–32 m/min depending on configuration, with ±1–2 mm length accuracy under PLC control. Budget in four parts: forming main unit, coil handling, punching/cutting hydraulics, and controls/auxiliaries — and always check what each quote includes before comparing.
This guide lists every module, explains capacity planning, gives a factory layout sketch, and compares starter vs automated budget tiers.
The 7 equipment groups, in line order
- Hydraulic decoiler — holds the coil and feeds strip under control. Sizes range from a single 3–5 t unit (coil ID φ508/φ610 mm) up to dual-head 6 t/head (12 t) units that allow the next coil to be loaded while the line runs. Coil width capacity (e.g. ≤600 mm) must match your strip.
- Leveler (guiding/leveling unit) — flattens the strip and removes coil set ahead of punching and forming. Multi-roll plated shafts (e.g. 3-up/4-down) are typical.
- Hydraulic pre-punch station — punches web holes (and slots) before forming, while the web is flat, so hole positions stay accurate. Common builds use 2–3 stations; patterns follow the profile drawing (e.g. 14.3 × 25.4 mm ellipses).
- Roll forming main unit — the heart of the line: 16–22 forming stations (auto-change lines often 20 stands) progressively bend flat strip into the C, Z or U profile. Key materials: rollers Cr12/GCr15 (HRC 58–60), shafts 40Cr (Φ75–100 mm) or 45# steel heat-treated, chain or gearbox drive.
- Cut system — hydraulic stop-cut (line pauses) or servo tracking cut (cut-on-the-fly, line keeps running). Post-cut with punch assist is common; length accuracy roughly ±1–2 mm under PLC.
- PLC control cabinet + touchscreen HMI — sets length, batch quantity, speed and (on auto-change lines) the C↔Z recipe. Remote assistance / network control optional.
- Run-out table — receives finished purlins for bundling; lengths commonly 6 m and up, sometimes with inkjet marking before the table.
Optional but valuable: inkjet marking (prints size/batch per piece) and automatic stackers/strappers at the high-volume end.
What real CZ purlin line specs look like
Published process data (ZTRFM) for a CZ auto-changeover line:
| Module | Example specification |
|---|---|
| Decoiler | Dual-head hydraulic, 6 t/head (12 t), width ≤600 mm, ID 450–550 mm, OD 1730 mm, brake, electric rotation |
| Forming | 20 stands; rollers Cr12 HRC 58–60; shafts 40Cr Φ90/75; chain drive; optional emboss rolls |
| Punch/cut | Hydraulic pre-punch, 3 stations; cut + punch power 15 kW; oil tank 300 L |
| Drive | Servo host 42 kW; high ~32 m/min, normal 12–18 m/min; 380 V / 50 Hz / 3-phase |
| Gauge | 1–3.2 mm Q235/Q355 (HR or GI); inkjet marking; 6 m run-out table; Xinje PLC; ZH/EN UI |
| Changeover | Auto C↔Z recipe in HMI, ~90–120 s |
Capacity planning: from 500 m to 5,000 m per shift
Estimate output with this sequence:
- Effective speed — use the normal forming speed for mixed work (e.g. 12–18 m/min) rather than the high-speed figure; punching cadence and cut system lower real throughput.
- Line utilization — assume 70–80% of shift time for coil changes, set-up and QC on real production.
- Meters per shift — a line doing 15 m/min average for 6 productive hours ≈ 5,400 m/shift theoretical, realistically ~3,800–4,300 m.
- Tonnage — multiply meters by kg/m for your section (gauge × developed width × steel density) to check whether coil handling and decoiler capacity match.
Choose decoiler class (3–5 t vs 6 t/head dual) by your largest coil and how often you tolerate changeover stops.
Factory layout essentials
Minimum line footprint and surroundings to plan:
- Line length: forming + cut + run-out typically needs ~20–30 m in one straight bay (e.g. a 15–20 m machine plus a 6 m run-out table and decoiler space).
- Coil storage: a bay beside the decoiler for current + next coils (forklift or coil car access).
- Finished-goods area: run-out table exit with space for bundling, strapping and forklift pickup.
- Power: check voltage (e.g. 380 V / 50 Hz / 3-phase or 220 V / 60 Hz per order), total connected load (motor + hydraulic, e.g. ~20–55 kW class) and air/oil cooling.
- Safety: full chain guards, machine guards closed during forming, and clear walkways.
Ask the supplier for the exact floor plan (footprint × power × weight) before civil work.
Budget tiers: starter line vs automated line
| Tier | What you get | Typical position |
|---|---|---|
| Starter single-profile | C-only or fixed-size line, manual change, stop-cut, basic decoiler | Lowest capital; fixed product |
| CZ convertible | Manual C/Z changeover, pre-punch, hydraulic cut, standard PLC | Balanced for mixed markets |
| Auto-changeover CZ | Recipe C↔Z (~90–120 s), servo host, dual-head decoiler, marking | High-mix shops; higher capital |
| CUZ / fully automated | C+U+Z auto width, stacker/strapper, remote support | Maximum flexibility and throughput |
Price moves most with: changeover type (manual → auto), cut system (stop-cut → servo tracking), punching stations, decoiler capacity, and control/automation level. Always request a spec-sheet quote — the same "purlin machine" name can mean very different line scopes.
Where to see real purlin line specifications
- Fully Automatic CZ Purlin Roll Forming Machine (ZTRFM product page) — complete line description and spec table
- C/Z Purlin Auto-Changeover Forming (ZTRFM Process Library) — module-by-module line spec
- C/U/Z Purlin Auto-Change Forming (ZTRFM Process Library) — CUZ line configuration
- Purlin / Channel / Beam process library
- Production equipment category (ZTRFM)
ZTRFM (zt-rfm.com) is a roll forming sourcing center operated by Zhongtuo Roll Forming (Hebei) Co., Ltd. Purlin standards commonly referenced include AISI S240 / ASTM A1003 (US) and GB/T 6723 (China) for cold-formed open sections.
Frequently Asked Questions (FAQ)
What equipment is needed for a purlin production line?
Seven groups in sequence: hydraulic decoiler, leveler, hydraulic pre-punch station, roll forming main unit, cut system, PLC control cabinet + HMI, and a run-out table. Optional: inkjet marking, stackers and strappers.
How much space does a purlin line need?
Typically a straight bay of roughly 20–30 m including decoiler and a 6 m run-out table, plus coil storage and finished-goods areas; confirm the exact footprint with the supplier.
How fast is a purlin production line?
Typical normal forming speeds 12–18 m/min for CZ lines with high-speed modes around 32 m/min; single-profile lighter lines can run faster, thicker gauge slower.
What is a pre-punch station for?
It punches web holes before forming while the web is flat, keeping hole positions accurate — standard on purlin lines (commonly 2–3 hydraulic stations).
What is the difference between stop-cut and servo tracking cut?
Stop-cut pauses the line to cut; servo tracking cut cuts on the move for higher throughput. Length accuracy is typically ±1–2 mm under PLC control.
How much does a purlin production line cost?
Prices vary widely with changeover type, cut system, decoiler and automation. Compare spec-sheet quotes (gauge, width, stations, power, decoiler, included line scope) rather than machine name or price alone.
