By producing 199,000 AD*STAR block bottom sacks in 24 hours on a single conversion line, Crafters Polypropylene Packages (PVT) Ltd. has achieved a production record that has never been reached before for this type of sack.
The woven plastic packaging producer, based in Karachi, Pakistan, installed two ad*starKON HX easy-open block bottom sack conversion lines from Starlinger & Co GmbH end of May 2023. Since the commissioning of the two lines, Crafters has been continuously ramping up production to meet the growing demand for AD*STAR sacks, a type of block bottom valve sack made of woven polypropylene tape fabric that is increasingly used worldwide for packaging dry bulk goods.
“It exceeded even our expectations when we counted the number of 199,000 produced sacks on the AD*STAR conversion line at the end of the day”, says Omair Rehman, Director of Crafters. “Such a high output is only possible due to the excellent production quality of the Starlinger equipment – from tape production to weaving, coating and printing up to sack conversion.
Because of the uniform high quality of the PP fabric, the Starlinger conversion lines operate with high efficiency and minimum downtimes. There is hardly any interruption of production due to jammed fabric or other technical issues except the necessary brief stops such as roll change. In addition, maintenance work as well as sack format change on the conversion line are quick and easy”, he adds with satisfaction. The company currently produces a total of close to 400,000 AD*STAR sacks per day on the two Starlinger conversion lines.
The lightest and strongest sack on the market
Crafters supplies the AD*STAR sacks primarily to the cement industry, one of their main customers being Pakistan’s biggest cement producer Lucky Cement. With a sack weight of 65g for a filling volume of 50 kg, AD*STAR sacks are currently the most lightweight type of sacks on the market for dry bulk goods such as cement. The combination of low packaging weight and high strength is possible due to the woven structure of AD*STAR sacks.
The tapes used for fabric production are made of polypropylene in a special extrusion process that includes stretching and annealing to achieve the special tape characteristics. After the weaving process on circular looms the produced fabric is coated and printed before it is converted to block bottom valve sacks.
“The process is well developed and standardised – you get the strongest sacks with the lowest possible weight”, explains David Grabenweger, AD*STAR Product Manager at Starlinger. “Compared to paper bags, for example, you save significant quantities of raw material. The strong and resistant PP fabric makes AD*STAR sacks tearproof and avoids sack breakage. This is a big advantage for cement filling companies as it helps to reduce cement loss due to broken sacks – a key factor which also contributes to the low overall CO2 footprint of AD*STAR sacks. In addition, they are a mono-material packaging and thus “designed for recycling”.
We also succeeded in using high shares of recycled polypropylene in tape production without compromising the fabric strength and other important characteristics of the sacks. AD*STAR sacks are, in fact, one of the most sustainable types of packaging for dry bulk goods”, Grabenweger adds.
The sacks can be equipped with a variety of different options such as an easy-open closure, which Crafters is using for their AD*STAR sacks. For this, a special easy-open strip is welded onto the sack bottom that can be torn off to pour out the cement. It avoids the use of knives or other cutting devices and allows controlled emptying of the sacks.
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