Best Practices for Using Stretch Film in Warehouses and Distribution

In the Australian logistics sector, the "last 100 metres" of the supply chain—the movement from the dispatch bay to the truck—is often where the most significant risks lie. While companies invest heavily in automated picking systems and transport fleets, load stability remains a critical vulnerability. A failure in pallet containment during transit across Australia’s vast and often rugged road network results in unsalable goods, rejected deliveries, safety hazards for unloaders, and reputational damage.

Effective pallet stabilisation is not merely about applying plastic around a load; it is a calculated engineering process involving containment force, film memory, and elastic recovery. For Australian warehouse managers, mastering stretch film application is essential for balancing unit load stability with cost-per-pallet metrics. This guide details the technical best practices for optimising stretch film usage, ensuring compliance with Australian safety standards, and minimising operational waste.

Selecting the Right Stretch Film for Your Load

The "one-size-fits-all" approach to procurement is the leading cause of film breakage and load failure. Selecting the correct film requires an analysis of the load profile, the wrapping equipment available, and the environmental conditions the pallet will face.

Cast vs. Blown Stretch Film: Key Differences and Applications

Understanding the manufacturing process of the film is the first step in selection.

• Cast Stretch Film: Produced by extruding molten polymer through a flat die onto a chilled roller.

  • Characteristics: High clarity (excellent for barcode scanning), quiet unwind, and consistent gauge. It relies on "cling" additives on one or both sides.

  • Best Application: Standard, uniform loads (Type A) in high-volume environments where noise reduction is necessary. It is generally more cost-effective per kilogram.

  • Limitation: Less puncture resistance than blown film.

• Blown Stretch Film: Produced by blowing heated resin into a bubble, which is then cooled and collapsed.

  • Characteristics: Superior puncture and tear resistance, high "memory" (elastic recovery), but noisy during unwind and often hazy/opaque.

  • Best Application: Heavy, irregular loads (Type C) with sharp edges (e.g., bricks, timber, machinery parts). Ideally suited for the Australian climate as it generally offers better heat resistance than standard cast films.

Understanding Film Gauge (Microns) and Performance

Film thickness is measured in microns (µm). However, with modern resin technology, a thinner film does not necessarily mean a weaker film.

• 12µm – 17µm (Standard/Light): Suitable for light uniform loads (under 400kg) such as tissue products, empty PET bottles, or snack foods.

• 20µm – 23µm (General Purpose): The industry standard for general warehousing. Suitable for loads between 400kg and 800kg.

• 25µm – 35µm+ (Heavy Duty): Required for heavy industrial loads (over 1000kg), construction materials, or pallets with sharp corners.

Operational Note: High-performance "nano-layer" cast films (often 33-55 layers) can now achieve the containment force of a traditional 23µm film at only 12–15µm, significantly reducing plastic consumption.

Pre-Stretched vs. Traditional Film: Cost and Efficiency Comparison

Pre-stretched film has been stretched near its breaking point during manufacturing (often wound onto the core at half the thickness of standard film).

• Traditional Film: Requires the operator (or machine) to stretch the film to generate tension. If applied manually without sufficient force, the load is merely "bagged," not secured.

• Pre-Stretched Film: Requires minimal physical effort to apply. It constricts immediately upon application.

• The Verdict: For manual wrapping operations, pre-stretched film is superior for ergonomics and consistency. For machine wrapping, traditional power pre-stretch film (which the machine stretches by 200–300%) offers the lowest cost per pallet.

Specialty Films: UV Stabilised, Vented, and Coloured Options

• UV Stabilised: Crucial for Australian supply chains where pallets may sit in open yards or on flatbed trucks exposed to high UV radiation. Standard film degrades and becomes brittle after prolonged sun exposure; UV film maintains integrity for 6–12 months.

• Vented (Breathable): Features die-cut holes to allow airflow. Essential for agricultural produce (preventing ripening acceleration), frozen goods (reducing condensation and freezing time), and hot-fill products.

• Coloured/Opaque:

  • Black/White: Security (concealing high-value goods like electronics) or preventing UV damage to the product itself.

  • Blue/Green/Red: Used for colour-coding inventory (e.g., quarantine stock, cross-dock freight, or specific carriers).

Essential Equipment for Warehouse Wrapping

The consistency of your wrap is determined by the interface between the operator and the equipment.

Manual Dispensers and Hand Wrappers

While low in capital expenditure, manual wrapping is the most expensive method in terms of labour and material consistency.

• Best Practice: Use ergonomic dispensers with a braking system. A "brake" allows the operator to create tension without friction burning their hands.

• The Risk: Operators rarely maintain consistent tension around all four corners of a pallet, and fatigue leads to "skipping" the bottom lock, which is critical for stability.

Semi-Automatic vs. Automatic Stretch Wrappers

• Semi-Automatic: An operator attaches the film to the pallet and presses start; the machine wraps the load and the operator cuts the film.

  • Target Volume: 15 – 50 pallets per day.

  • ROI: Consistent pre-stretch (often 200%+) reduces film usage by 30–50% compared to hand wrapping.

• Automatic: Conveyor-fed systems with automatic film attach, cut, and wipe-down. No operator intervention required.

  • Target Volume: 50+ pallets per hour or high-speed production lines.

Turntable vs. Rotary Arm Machines: Choosing for Space and Load Type

• Turntable: The pallet sits on a disc that spins.

  • Pros: Compact footprint, lower cost.

  • Cons: Unsuitable for extremely heavy loads (strain on motor) or very light/unstable loads (centrifugal force may throw boxes off before they are secured).

• Rotary Arm: The pallet sits stationary on the floor while an arm rotates around it.

  • Pros: Ideal for unstable, light, or extremely heavy loads. High throughput.

  • Cons: Requires a larger safety footprint/cage.

Mastering Containment Force: The Key to Load Stability

There is a fundamental misconception in warehousing that "more layers equals more stability." This is false. The critical metric is Containment Force.

Defining Containment Force vs. Wrap Tension

• Wrap Tension: The force applied to the film as it is pulled off the roll (the "tightness").

• Containment Force: The cumulative force the film exerts on the load to hold it together. It is the sum of the film’s tension, the number of layers applied, and the film’s thickness.

High tension does not guarantee high containment force if the film relaxes significantly after application.

Recommended Containment Force Standards by Load Weight (kg)

While specific requirements vary by load profile, industry guidelines suggest the following minimum containment force values:

How to Measure Containment Force Correctly

You cannot judge containment force by poking the pallet. You must use a Containment Force Tool (often a load cell plate or a specialised spring scale stick).

1. Placement: Insert the measuring tool between the film and the product, facing away from the pallet (typically at the top, middle, and bottom of the load).

2. Measurement: Pull the tool away from the load until the film separates by 10cm (or follows the tool’s specific calibration).

3. Recording: Note the reading in kilograms or pounds.

4. Audit: Perform this check weekly to ensure machine pre-stretch rollers haven't worn down, which would reduce delivered force.

Optimal Wrapping Techniques and Procedures

Whether wrapping by hand or machine, the geometry of application determines success.

The "Locking to Pallet" Technique for Base Security

The single most common cause of load failure is the separation of the goods from the pallet base during cornering or braking.

• The Technique: The film must cover the wooden/plastic bearers of the pallet itself, not just the cartons sitting on top.

• Execution: Ensure at least 7-10cm of film wraps around the pallet base. This creates a mechanical bond between the freight and the transport medium.

The 3-1-3-1 Wrapping Pattern for Maximum Stability

A standard robust pattern for general freight:

1. 3 Bottom Revolutions: Secure the load to the pallet (the lock).

2. Upward Cycle: Spiral up with appropriate overlap.

3. 3 Top Revolutions: Secure the top layer (often the most vulnerable to vibration).

4. Downward Cycle: Spiral down.

5. 1 Final Bottom Revolution: Seal the tail.

Managing Overlap: The 30-50% Rule

As the film spirals up the pallet, each layer should overlap the previous one by 30% to 50%.

• Less than 30%: Creates weak points where products can bulge or shift.

• More than 50%: Excessive material usage (waste).

Dealing with Load Profiles: Type A, B, and C Loads

Machine settings should be adjusted based on the load profile:

• Type A (Uniform): Same size cartons, no protrusion. Standard tension is acceptable.

• Type B (Irregular): Mixed pallet with some variation. Requires moderate tension adjustments.

• Type C (Protruding): Differing sizes with sharp edges or overhangs exceeding 50mm. Requires lower tension to prevent film puncture or product crushing, compensated by higher revolution counts.

Roping and Cabling for Heavy or Irregular Loads

"Roping" involves bunching the full width of the film into a tight "rope."

• Application: This is best used to lock the load to the pallet base (manual or machine-assisted).

• Why: A roped film has incredible tensile strength and acts like a strap, preventing the load from sliding off the pallet. Many modern machines have an automatic "roping" feature for the cycle start.

Safety and Ergonomics in the Packing Area

Warehouse safety is paramount. Manual wrapping is a leading cause of musculoskeletal disorders in Australian warehouses.

Minimising Physical Strain and Injury During Manual Wrapping

Operators manually wrapping pallets often walk backwards in a circle while bent over at the waist to reach the bottom of the pallet. This creates a high risk of dizziness, trip hazards, and lower back strain.

• Correct Posture: Walk forwards where possible. Use a "walking stick" dispenser that allows wrapping the bottom of the pallet without bending.

• Rotation: Rotate staff to prevent repetitive strain injury (RSI).

Operational Safety Protocols for Machine Wrapping (Safe Work Australia Guidelines)

Automatic wrappers are powerful industrial machinery.

• Exclusion Zones: Automated wrappers must be guarded by fencing with interlocked gates. If a gate opens, the machine must emergency stop (E-Stop).

• Forklift Separation: Establish clear traffic management plans separating pedestrians (wrapping operators) from forklifts loading the turntables.

• Safety Edges: Rotary arm wrappers should be equipped with bump-strip safety edges that cut power immediately if the arm impacts an obstruction.

Sustainability and Cost Management

Reducing plastic usage is both an environmental and financial imperative.

Strategies for Down-Gauging and Right-Gauging

"Right-gauging" means finding the thinnest film that still meets the required containment force.

• The Shift: Moving from a 23µm standard film to a 17µm high-performance nano-film can reduce plastic weight by 25% while maintaining stability.

• ROI Calculation: While high-performance rolls cost more per roll, they contain more metres and use less weight per pallet, lowering the landed cost.

Recycling Programs for Used Stretch Film (Soft Plastics & LDPE #4)

Clear LLDPE (Linear Low-Density Polyethylene) stretch wrap is highly recyclable in Australia.

• Segregation: It is vital to keep stretch film separate from strapping (PET/PP) and adhesive tapes. Contamination renders the bale unrecyclable.

• Compaction: Use balers to compress waste film; loose film is expensive to transport (transporting air).

• Vendors: Engage with waste partners who provide certification of recycling to support your ESG reporting.

Proper Storage of Film Rolls to Prevent Degradation

Film is sensitive to temperature.

• Heat: Storing film in a hot shipping container or near skylights can cause layers to block (fuse) together, causing breaks during unwind.

• Humidity: Paper cores absorb moisture. If a core swells or softens, it will not fit the machine mandrel or dispenser, rendering the roll useless.

• Protection: Keep film in its box until the moment of use. Do not drop rolls; a dented edge will cause the film to snap every time it unwinds to that point.

Common Stretch Wrapping Mistakes to Avoid

Under-Wrapping and "Barrelling" Effects

• Barrelling: Occurs when wrap tension is too high in the middle of the load, but not the top or bottom. This squeezes the load into an hourglass shape, damaging cartons and reducing stacking strength.

• Solution: Adjust the carriage speed and tension settings to ensure even force distribution.

Neglecting Equipment Maintenance and Calibration

A wrapping machine with dirty rollers cannot perform pre-stretch.

• The Issue: Tackifier build-up on pre-stretch rollers reduces the friction needed to stretch the film. Instead of getting 250% stretch (1m becomes 3.5m), you might only get 50%, skyrocketing costs.

• Fix: Clean rollers weekly with isopropyl alcohol or approved solvent.

Applying Incorrect Tension for Fragile Loads

Applying 8kg of force to empty PET bottles or tissue boxes will crush the corners.

• Fix: Use a machine with "soft start" and variable tension controls. Reduce tension and increase film overlap layers to achieve stability without crushing.

Conclusion

Optimising stretch film usage is a balancing act between three critical factors: Load Stability, Operational Cost, and Safety.

For Australian warehouse managers, the goal is to achieve the lowest cost per chemically safe load—not the lowest cost per roll of film. By transitioning from manual to machine application where volume permits, auditing containment force regularly, and selecting the correct high-performance films, operations can significantly reduce transit damage and plastic waste.

Remember: The film is the only thing standing between your product and a potential accident on the highway. Treat the wrapping process with the engineering precision it deserves.

Frequently Asked Questions (FAQs)

Q: What is the difference between stretch wrap and shrink wrap? A: Stretch wrap is elastic; it is stretched around a load and the elastic memory holds the load tight. Shrink wrap is applied loosely and then heated (using a heat gun or tunnel), causing it to shrink and conform to the product. Stretch wrap is standard for pallets; shrink wrap is typically used for retail packaging or weatherproofing heavy machinery.

Q: How much film should be used on a standard pallet? A: This varies by load height and film type, but a standard 1.8m high pallet wrapped by a calibrated machine with 250% pre-stretch typically uses between 150g and 250g of film. If you are using over 400g per pallet, you may be using inefficient settings or outdated film technology.

Q: What is "neckdown" in stretch wrapping? A: Neckdown refers to the narrowing of the film's width as it is stretched. For example, a 500mm wide roll might narrow to 400mm when stretched significantly. High-quality films resist neckdown better, maintaining coverage and requiring fewer revolutions to cover the pallet.

Q: Can I recycle stretch film with paper labels attached? A: Ideally, no. While small paper labels are sometimes tolerated by recyclers, large amounts of paper contamination can degrade the quality of the recycled resin. Where possible, apply SSCC labels over the stretch wrap, or remove them before baling the waste plastic.

Q: Why does my film keep snapping during the machine cycle? A: Common causes include:

1. Nicks in the roll edge: Check if the roll was dropped.

2. Dirty rollers: Tack build-up causing slippage.

3. Tension too high: The film is being stretched beyond its yield point.

4. Sharp load edges: The pallet contents are puncturing the film (requires lower tension or heavier gauge film).

Q: What is the optimal pre-stretch percentage for general warehousing? A: For modern semi-automatic machines using high-performance film, 200% to 250% is the industry sweet spot. This means 1 metre of film off the roll becomes 3 to 3.5 metres on the pallet. Going higher (300%+) requires specialised high-end film and perfectly maintained equipment.