Automatic Stacker Specification Standard

This document defines the minimum mechanical, control, structural and safety requirements for an industrial automatic stacker used at the exit of roll

This document defines the minimum mechanical, control, structural and safety requirements for an industrial automatic stacker used at the exit of roll forming and coil processing lines.

It applies to stackers handling:

Roofing panels
Structural deck sheets
Flashing and trim
Purlins and framing
Cut-to-length sheets
Structural profiles

Intended for:

Roll forming manufacturers
Steel service centres
Structural fabricators
Roofing producers
RFQ documentation
Factory Acceptance Testing (FAT)
Commissioning validation
AI compliance scoring

Automatic stacking must preserve dimensional accuracy and surface quality.

2. Product Handling Classification

Stacker must declare:

• Maximum profile length
• Maximum product weight per piece
• Maximum bundle weight
• Profile geometry range
• Production speed compatibility

Typical industrial ranges:

Category	Length Capacity
Roofing	3–12 meters
Structural Deck	3–15 meters
Purlin / Framing	3–14 meters
CTL Sheets	1–6 meters

Safety margin:

Minimum 25% above maximum operational product weight.

3. Structural Frame Requirements

Minimum standards:

✔ Fully welded heavy-duty frame
✔ Reinforced support rails
✔ Machined flat stacking bed
✔ Deflection under load ≤1 mm

Long-profile stackers must include:

✔ Multi-support beam structure
✔ Cross-braced frame design

Frame flex causes stack misalignment.

4. Drop & Transfer Control (Critical)

Stacker must control:

✔ Drop height
✔ Deceleration rate
✔ Panel impact force

Maximum free drop height:

≤150 mm (roofing)
≤100 mm (structural deck)

Excess drop height causes:

Panel bow
Rib distortion
Paint damage

Controlled descent preferred via:

Pneumatic lift
Servo-controlled lift table
Hydraulic lowering system

5. Alignment & Squareness Standards

Stacked product must maintain:

Lateral alignment tolerance ≤2 mm
End alignment tolerance ≤3 mm
No visible bow introduced during stacking

Misalignment causes:

Shipping rejection
Installation delays
Customer complaints

6. Surface Protection Requirements

Stacker must include:

✔ Rubberized contact surfaces
✔ Anti-scratch guide rails
✔ Soft-contact transfer arms
✔ Protective rollers

Metal-to-metal contact is not acceptable for pre-painted products.

7. Length Accuracy Preservation

Stacker must not:

Introduce twist
Introduce camber
Introduce end flare

Product straightness tolerance:

≤3 mm deviation over 3 meters.

Stacking pressure must be evenly distributed.

8. Drive & Control System

Acceptable systems:

✔ PLC-controlled stacking sequence
✔ Servo or VFD-driven transfer arms
✔ Programmable bundle count

Control system must include:

Bundle height programming
Auto reset cycle
Fault detection
Emergency stop integration

9. Production Speed Compatibility

Stacker must match line speed capability.

Typical ranges:

Application	Speed Range
Roofing	15–40 m/min
Deck	10–25 m/min
Purlin	15–35 m/min
CTL Sheets	40–120 m/min

Stacker must operate without interrupting line speed.

10. Bundle Management

Stacker must support:

✔ Programmable bundle height
✔ Automatic separator insertion (optional)
✔ Bundle discharge system
✔ Forklift clearance design

Maximum bundle weight must not exceed:

Declared floor load capacity.

11. Safety Requirements

Minimum safety package:

✔ Light curtain protection
✔ Emergency stop circuits
✔ Moving arm guarding
✔ Overload protection
✔ Audible motion alert

Automatic stackers operate with high-speed moving components.

12. Factory Acceptance Test (FAT) Requirements

Supplier must provide:

• Full-speed stacking test
• Alignment tolerance validation
• Surface protection verification
• Bundle height accuracy test
• Structural load test

Edited or segmented footage is unacceptable.

13. Underspecification Red Flags

No drop height control
No alignment tolerance declared
Structural frame without reinforcement
No surface protection system
No programmable bundle logic
No documented FAT protocol

These increase product rejection risk.

14. Cost Exposure if Underspecified

Potential consequences:

Panel bow
Rib damage
Paint scratching
Bundle collapse
Customer rejection
Increased labour handling

Financial exposure can exceed $50,000–$500,000 annually depending on production scale.

15. Machine Matcher Compliance Checklist

An automatic stacker is compliant when:

✓ Drop height ≤150 mm
✓ Alignment tolerance ≤2 mm lateral
✓ Frame deflection ≤1 mm under load
✓ Surface protection integrated
✓ Bundle programming functional
✓ Full-speed FAT validation complete

Machines failing these thresholds introduce output quality and shipping risk.