SunAura Ships a 14-Head Multihead Weigher with Nitrogen-Flush Flow Wrapper to a Polish Frozen Berry Producer

SunAura Machinery has commissioned a 14-head multihead weigher with a servo-driven, nitrogen-flush pillow flow wrapper for a frozen berry producer in northern Poland. The customer packs frozen strawberries, blueberries and mixed berry blends in 250 g, 500 g and 1 kg pillow bags for retail and foodservice, at a target of 45–60 bags per minute. The project replaced a manual weigh-and-pack station that could not meet export fill-weight tolerances.

Frozen berries are not “snacks that happen to be cold.” They thaw on contact with warm buckets, they bruise when dropped from height, and the bag needs a nitrogen flush because oxygen accelerates off-flavor and freezer burn. A standard dry-goods multihead weigher and a basic flow wrapper would have under-delivered on all three. This line was specified around them.

Why a 14-Head Weigher — and Why Not 10 or 18

Weighers are chosen by product and speed, not by the brochure. A 10-head weigher tops out around 40–50 weighings/min and suits steady, free-flowing product; an 18-head reaches 80+ weighings/min but costs 30–40% more and overspeeds a 60-bpm bag machine. Frozen berries mix loose and lightly clumped fruit, which slows each weigh cycle, so we specified a 14-head unit as the middle: enough heads to hold 60 bpm on a clumpy product, without paying for capacity the downstream wrapper cannot use.

Two details mattered more than head count. First, the weigh buckets are made of food-grade stainless with Teflon-coated discharge gates and anti-stick surfaces — berries that thaw halfway stick to standard buckets and ruin the next weigh. Second, the weigher runs a slow-dump program: the discharge chute opens gently rather than snapping, because a strawberry dropped from 400 mm into a bag bruises and turns mushy on thawing. That is why we also specified short chutes and soft bag support.

Nitrogen Flush on the Pillow Wrapper — and Why Ordinary Film Would Not Do

Frozen berries oxidize in ordinary air. The pillow wrapper we specified injects a controlled nitrogen flush into the bag forming tunnel, displacing oxygen before the longitudinal and end seals close. Paired with an EVOH barrier film rather than plain PE, the bag keeps oxygen below 2% and extends freezer shelf life from roughly 6 months to 12+ months, and reduces off-flavor. A basic flow wrapper without gas flushing would have packed the same fruit but with a shorter shelf life and higher freezer-burn complaint rate.

The wrapper itself is a servo-driven intermittent-motion model suited to barrier laminates — continuous-motion wrappers run hotter and faster, but intermittent sealing holds a tighter, cooler seal on EVOH film at 60 bpm, which is exactly the customer’s speed band.

Who This Line Is For — and What We Would Specify Differently

This configuration targets frozen-fruit and vegetable packers at roughly 30–80 bags/min running 250 g–2 kg pillow bags, where net-weight accuracy and shelf life matter more than absolute speed. Buyers above 120 bags/min should step to an 18-head weigher on a continuous-motion wrapper; buyers below 30 bags/min are better served by a semi-automatic scale and a manual pack station. We did not push the customer to the bigger machine because the bag machine could not use the extra weighings.

The line passed FAT at our Qingdao workshop with the customer’s actual frozen berries (run straight from the freezer), checked net-weight tolerance and seal integrity, then shipped with spare weigh buckets, a film reel sample pack and commissioning support covered under our after-sales service terms. For more on how to size the weigher heads, see the related buying guide on multihead weighers.