Strapping and stretch wrap do different jobs. Strapping holds the load down and resists vertical movement; wrap resists lateral movement and weathering. Heavy export pallets usually use both.
What about recycled or green strap?
Both PET and PP are available in recycled content. Check the weld and tension performance — regrind strap can be inconsistent. Specify a certified recycle content grade if your customers require it.
Summary
Choose PP for light, rigid, short moves; choose PET for heavy, settling, long-freight loads. Match the strap to the machine head, and size width and tension to the pallet weight. If you are specifying an end-of-line cell, send us your product, pallet weight and destination and we will spec the strap and head that hold the load all the way to the customer.
Related reading
- Robotic case packing cell for a Colombian coffee roaster
- Steam vs IR vs hot-air shrink tunnels for sleeve labels
Light bundles use 5–9 mm; medium cartons use 12 mm; heavy pallets use 15–19 mm. The strap width, tension and number of straps per pallet are set by the load test, not by guesswork.
Does PET strap need a stretch wrapper too?
Strapping and stretch wrap do different jobs. Strapping holds the load down and resists vertical movement; wrap resists lateral movement and weathering. Heavy export pallets usually use both.
What about recycled or green strap?
Both PET and PP are available in recycled content. Check the weld and tension performance — regrind strap can be inconsistent. Specify a certified recycle content grade if your customers require it.
Summary
Choose PP for light, rigid, short moves; choose PET for heavy, settling, long-freight loads. Match the strap to the machine head, and size width and tension to the pallet weight. If you are specifying an end-of-line cell, send us your product, pallet weight and destination and we will spec the strap and head that hold the load all the way to the customer.
Related reading
- Robotic case packing cell for a Colombian coffee roaster
- Steam vs IR vs hot-air shrink tunnels for sleeve labels
Only if the strapping head is rated for both. Most heads are sold for one material; switching requires a different weld head and a tension re-set. Confirm before buying.
How wide should the strap be?
Light bundles use 5–9 mm; medium cartons use 12 mm; heavy pallets use 15–19 mm. The strap width, tension and number of straps per pallet are set by the load test, not by guesswork.
Does PET strap need a stretch wrapper too?
Strapping and stretch wrap do different jobs. Strapping holds the load down and resists vertical movement; wrap resists lateral movement and weathering. Heavy export pallets usually use both.
What about recycled or green strap?
Both PET and PP are available in recycled content. Check the weld and tension performance — regrind strap can be inconsistent. Specify a certified recycle content grade if your customers require it.
Summary
Choose PP for light, rigid, short moves; choose PET for heavy, settling, long-freight loads. Match the strap to the machine head, and size width and tension to the pallet weight. If you are specifying an end-of-line cell, send us your product, pallet weight and destination and we will spec the strap and head that hold the load all the way to the customer.
Related reading
- Robotic case packing cell for a Colombian coffee roaster
- Steam vs IR vs hot-air shrink tunnels for sleeve labels
PET vs PP Strapping for Palletizing: When to Choose Polyester vs Polypropylene Strap
Most packaging line buyers pick strapping by price per coil. That is a mistake. PET (polyester) strap and PP (polypropylene) strap look similar on a reel, but they stretch, recover and hold load very differently — and putting the wrong strap on a heavy pallet is how you get a load that arrives at the customer’s door half-loose. This guide lays out the difference, when each earns its place, and where the cheap PP choice quietly costs more.
The core difference: elongation and recovery
Strapping works by stretching the strap around the load and letting it contract. The number that matters is not tensile strength alone — it is elongation at break and elastic recovery. PP strap stretches more (typically 15–25% elongation) but relaxes over time, so a tight load on Monday can be loose by Friday. PET strap stretches less (around 10–15%) but holds tension far better and recovers under load. For a heavy, settling pallet — bags, boxes that compress, loads that travel for weeks — PET keeps its grip. For a light, rigid bundle that never settles, PP is fine.
| PP (polypropylene) strap | PET (polyester) strap | |
|---|---|---|
| Typical width | 5–15 mm | 12–19 mm |
| Elongation | 15–25%, relaxes over time | 10–15%, holds tension |
| Tension retention | Poor over long freight | Excellent, recovers under load |
| Elongation recovery | Low | High |
| Climate sensitivity | Softens in heat | Stable over wide temperature range |
| Relative cost per coil | Lower | Higher |
| Best for | Light bundles, carton units, short moves | Heavy pallets, bags, long freight, outdoor storage |
| Not for | Heavy settling loads, long sea freight | Very light, low-tension bundles (overkill) |
When PP is the right choice
Polypropylene is the economical choice for light to medium loads that do not settle. Think corrugated cases on a pallet that are already rigid, printed bundles, tissue and paper products, and internal factory moves where the pallet goes from line to warehouse in minutes. PP runs on cheaper, smaller strapping heads, it seals by friction or heat, and it is forgiving on low-tension machines. If your product is light, your freight is short, and your pallets are not exposed to temperature swings, PP will save money on every coil.
When PET earns the premium
Polyester strap is the default for heavy loads that settle: bags of grain, sugar, cement, animal feed; stacked cases that compress as they sit; loads that travel by sea for weeks; pallets stored outdoors through seasonal temperature changes. PET’s high tension recovery means that as the load settles, the strap tightens rather than going slack. It also performs across temperature ranges where PP softens in a hot container or a sun-heated warehouse. For export freight and anything that ships on a stretch-hooded or wrapped pallet, PET is the conservative choice. It costs more per coil, but a rejected load or a customer complaint costs far more.
The machine side: strap head matters too
The strap material has to match the strapping head. PP runs on friction-weld or heat-seal heads at lower tension. PET needs a weld head rated for polyester — it requires higher heat and tension, and a machine sold only for PP will not seal PET reliably. If you are choosing a strapping machine as part of an end-of-line cell, tell the supplier the strap you intend to run. SunAura builds strapping heads as part of the palletizing and end-of-line range, and the head, tension setting and conveyor are matched to the strap width and load weight. Buying a cheap strapper and then forcing PET through it is a common mistake that gives weak welds and snapped straps.
The hidden cost of cheap PP on a heavy load
When PP is used on a settling load, the failure mode is not dramatic — the strap just goes slack over a week. The customer opens the container to find a leaning pallet, torn bags, or cases shifted into each other. The freight claim, the re-work, and the damage to the customer’s confidence are far larger than the per-coil saving of PP over PET. A useful rule: if the load weighs more than roughly 300 kg, settles at all, or travels more than a few hundred kilometers, use PET. Under that, PP is fine. SunAura includes a strap recommendation in every quotation based on product, pallet weight and destination, rather than assuming a default.
Steel strap vs plastic: the third option
Worth a mention: steel strap still appears for very sharp, heavy or abrasive loads — coils, lumber, stone. It does not stretch at all, it cuts hands, and it requires a dedicated seal system. For almost all food, beverage, consumer goods and bagged product lines, plastic strap (PET or PP) is the safer, cleaner and faster choice. Steel only makes sense where the product is genuinely too abrasive for plastic or where a regulatory or load-securement standard demands it.
Strap grade, coil length and the real cost per pallet
Buyers compare price per kilogram of strap and miss the coil math. A thinner, cheaper strap that breaks or relaxes means more wraps per pallet and more coil changes. Calculate cost per pallet: strap width times length used times price per metre. PET looks more expensive per kilo, but a narrower PET strap at correct tension often uses fewer metres per pallet than a slack PP wrap. Also check the core size and coil length — a coil that runs out mid-shift costs more in operator time than the strap itself. For high-volume lines, ask for the long-length coils that reduce changeovers, and confirm the core diameter matches your strapping head’s reel holder. A premium strap with consistent welds and tension retention is cheaper than a bargain strap that produces reject pallets.
Tension settings: not as tight as possible
New operators crank tension to maximum and crush corrugated cases or bag loads. The correct tension is the lowest that holds the load through transit. For rigid cases, modest tension; for bagged product that settles, higher tension with a tension-reduction setting so the strap does not saw through the bag. PET’s recovery means you can set a moderate initial tension and let the strap tighten as the load settles; PP will not do that, so over-tightening PP on a settling load just deforms the pallet. Modern strapping heads have tension recipes per product — set one for light cartons, one for bagged bulk, one for drums — and the operator selects at the HMI rather than turning a knob.
Strap pattern: how many straps, which orientation
A pallet strapped with two straps across the width is rarely enough for export. The pattern is part of the load-securement calculation: typically two to three straps lengthwise, plus optional top-over-bottom bands for tall loads. Light, stable cartons may take two; bagged bulk on a slip sheet needs three, often paired with a top frame or stretch wrap. SunAura specifies the pattern at the quotation stage based on pallet weight, height and destination, and the strapping machine runs that pattern automatically after the palletizer. If your freight carrier or customer has a load-securement standard (many retailers audit incoming pallets), hand us that document — the machine can be programmed to match it exactly.
Safety and operator habits
Strapping machines cut strap at high tension, and a stray end can snap back. Safety interlocks on the strap feed, an auto-threading mechanism, and a good blade guard matter more than operators think. SunAura specifies auto-threading heads so operators do not feed strap by hand, and the control panel locks out the weld cycle when the guard is open. Cheap machines without these features cause the avoidable injuries that make maintenance teams hate the end of the line. If you are automating an existing manual strapping station, budget for the guard and interlocks — they are the difference between a machine that runs safely for ten years and one that gets bypassed.
Load-securement standards and retailer audits
If your pallets go to a big-box retailer, a DC, or an ocean carrier, expect an audit. Retailers in particular specify how many straps, the strap material, and whether stretch wrap is required; a pallet that arrives with a single loose PP band can be refused or fee’d. When you are specifying an end-of-line cell, hand us the securement standard your customer requires and we will program the strapping pattern to match — number of straps, orientation, tension setting, and a label or photo record if needed. This is also where PET pays back: a load that has not settled on arrival is a load that passes the audit. Cheap PP on a load that shifts across the ocean is the kind of problem that ends up as a chargeback, and chargebacks dwarf the strap saving.
Sustainability and recycled content
Both PP and PET are recyclable, and both are available with recycled content. The practical point for a buyer is consistency: regrind strap varies in weld quality and tension, so if you specify recycled content, require a certified grade and test a coil before committing. PET is also lighter than steel strap and uses less material per pallet for the same hold, which is part of why it displaced steel on most plastic-wrap applications. For customers asking about packaging footprint, moving from steel to PET strap reduces both weight and disposal cost — and the strapping machine itself uses far less energy than a steel seal station.
Integration with the palletizer
A strapping machine is not a standalone machine on an automated line — it sits between the palletizer and the stretch wrapper, and the sequence matters. The palletizer places the load, the conveyor moves it to the strapping station, the straps fire, and the load moves to the wrapper. If the handshakes are wrong, the pallet arrives before the station is ready or leaves before the weld cools, and you get snapped straps or half-secured loads. SunAura programs the palletizer, strapper and wrapper as one sequence on a shared HMI: the operator selects the product, the palletizer builds the right layer count, the strapper applies the programmed number of straps, and the wrapper applies the chosen film pattern. Buying these three machines from three suppliers and expecting them to talk is where most end-of-line projects stall; one integrated sequence removes that argument.
How to test strap before committing to a supplier
Do not pick strap by a datasheet alone. Ask for a coil of each candidate grade and run your actual pallets for a week: strap the load, let it sit, and check tension after three and seven days. Look for necking on the strap (a sign it is over-stretched and will break), for weld cracks at the seal, and for the strap going slack on a settling load. A cheap strap that passes the initial pull test but relaxes in a week is the expensive option. This same test is the FAT extension for the strapping machine itself — run it on your product, not on a dummy pallet.
FAQ
Can I run both PP and PET on the same machine?
Only if the strapping head is rated for both. Most heads are sold for one material; switching requires a different weld head and a tension re-set. Confirm before buying.
How wide should the strap be?
Light bundles use 5–9 mm; medium cartons use 12 mm; heavy pallets use 15–19 mm. The strap width, tension and number of straps per pallet are set by the load test, not by guesswork.
Does PET strap need a stretch wrapper too?
Strapping and stretch wrap do different jobs. Strapping holds the load down and resists vertical movement; wrap resists lateral movement and weathering. Heavy export pallets usually use both.
What about recycled or green strap?
Both PET and PP are available in recycled content. Check the weld and tension performance — regrind strap can be inconsistent. Specify a certified recycle content grade if your customers require it.
Summary
Choose PP for light, rigid, short moves; choose PET for heavy, settling, long-freight loads. Match the strap to the machine head, and size width and tension to the pallet weight. If you are specifying an end-of-line cell, send us your product, pallet weight and destination and we will spec the strap and head that hold the load all the way to the customer.