Webster Griffin Ltd
Brooklands Park
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Crowborough,  TN6 2JD
England (UK)

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> Home > Case Studies > Plastic Pellets, Resin Chips (PET)
Plastic Pellets Resin Chips PET

Full Case Study on Italpet Installation:


Patented 'Semi Suspension' Filling System

  Patented 'Semi Suspension' Filling System


Webster Griffin installed a big bag filling system at Italpet Preforme Pallanza on the shores of Lake Maggiore in Northern Italy for bagging PET chips (Polyethylene Terephthalate) into 800, 1000 and 1200kg four loop big bags.

Italpet Preforme's sister company, Cobarr Plastics Rome,  were the second company, after Crystal Polymers UK, to select a Webster machine for the bagging of PET chips, now over 40 such systems are operating world wide  - the most advanced being at Italpet.

Because PET chips are used for making carbonated soft drinks bottles and clear rigid food packaging strict quality assurance procedures are in place at Italpet Preforme and traceability of all product throughout manufacturing, bagging and despatch is of paramount importance.

Operated by one man, who places an empty bag onto the machine every 90 seconds, the Webster Griffin system runs for 8-16 hours/day but in times of high demand will run for 24 hours/day, 7 days/week.

As this is the only bagging line at Italpet reliability and versatility are essential –bag size and/or weight changeovers often have to be done several times per shift, therefore, such features as self adjustment for different bag sizes, integrated check weighing of filled bag weights, and automatic printing of an identification label for each bag are considered to be essential.

The bagging machine is fed with product from two stainless steel silos above the bagging hall, after filling and tagging bags are conveyed into the adjacent warehouse where they are unloaded by two fork lift trucks working in sequence.     The new Webster Griffin line comprises:-

Semi Suspension Filling Ensures a Neat Square Bag Every Time


"Semi suspension" filling ensures a neat square bag every time

Owing to the high value of PET resin at up to $2,000 per tonne, Italpet Preforme needed to reduce product give away and stipulated an accuracy of +/- 500g – 1000g/bag dependable accuracy is ensured by Webster’s ‘self optimising’ digital weighing controller, via a ‘Querty’ keypad the weighing system can be loaded with 100 different sets of instructions for different bag weights and product bulk densities, these pre-set instructions are re-called by entering an alpha numeric code.

An RS232 output links the weighing system to an barcode and label printer, a printed label is placed in a pocket on each bag and displays a unique bag identification number, as well as the final customers name, product grade, batch number, date, time and the actual net weight of product in the bag.     This label acts as a passport and travels with the bag to its final destination.

The weigh system is also connected to Italpet Preforme's DCS, Plant Computer, which records and monitors the performance of the bagging station.   A database of production  data, which can be interrogated according to customer name, product grade, batch and time will provide a central pool of easily accessed information on the history of every bag which has been filled by the system.

When filling big bags at high speed it is very important that the loose inner PE bag does not rupture as it is filled, to avoid this problem the empty bag is raised up and completely inflated by a motor driven fan before the two stage product feed valve above the IBC-PF3 is opened and chips  are allowed to pour into the bag hanging below.  

For Italpet Preforme it is crucial that filled bags are stable and sit squarely on the pallet.   Whatever the bag height a stable square pack is assured by the Webster machine which suspends the bag during filling and lowers it down onto the pallet at the end of the auto weigh fill cycle.

To further reduce operating costs Italpet Preforme sought to reduce expenditure on packing materials by using bags which are as small as possible – unfilled space is a bag is a waste of money and avoided by Webster’s unique method of clamping the bag neck and holding it in tension throughout the whole filling cycle.

Video available on request

Layout Drawing of System:
Available on request

Webster Griffin PET Packing Reference World-Wide:

  • Asia PET Thailand – 1 system
    Cobarr Plastics – 1 system
  • Crystal Polymers – 1 system
  • Dae-Ha Synthetic Fibres Inc – 2 systems
  • Futura Polymers – 2 systems
  • Gatron Industries Pakistan – 1 system
  • Indopet Thailand – 1 system
  • Indorama Synthetics India – 1 system
  • JG Summit Petrochemicals – 1 system
  • Polysindo (Texmaco) – 1 system
  • PPSC – 1 system
  • PT Indorama Synthetics – 3 systems



  • SABIC – 2 systems
  • SASA – 1 system
  • Tiszai Vegyi Kombinat – 1 system
  • Tong Kook Synthetic Co. – 3 systems
  • Voridian Argentina – 4 systems
  • Voridian Spain – 4 systems
  • Voridian Malaysia – 4 systems
  • Voridian Rotterdam – 1 system
  • Exxon – 1 system





Project Specification

Application: High speed big bag filling system
Client: Italpet Preforme S.p.A, Pallanza Italy
Product Packed: PET Resin/Plastic used to make the bottles for carbonated beverages and mineral water.
Bag Type: Four loop woven polypropylene bags 800-1200kg
Bagging Rate: 200,000 TPA 30-40 big bags/hour (30 ton/h)
System Comprising: IBC-PF3 big bag filling machine
Ticket label printer
Empty pallet magazine
Bag handling conveyors
Operators platform
Why Did Italpet Select Webster Griffin:
  • Italpet Preforme's sister company Cobarr Plastics, Rome, had operated a high speed Webster Griffin bagging system since 1994.
  • Owing to the high value of PET resin, Italpet Preforme stipulated an accuaracy of +/- 500g per 1000g/bag which was ensured by Webster Griffin's 'self optimising' weighing technology.
  • Easy/quick bag size changeover - the IBC-PF3 is 'self adjusting' for different bag sizes.
  • One man operation