BLOOD STOPPING Rubber tube stoppers are molded under a vacuum
In order to exclude air bubbles and vapour generated by high temperature and pressure from blood collection tube stoppers, Italy-based rubber components manufacturer Datwyler Pharma Packaging (DPP) makes use of vacuum pumps manufacturer Busch Vacuum Pumps and Systems’ Cobra dry screw vacuum pumps in its tube stopper manufacturing process.
DPP’s production facility primarily produces syringe plungers and sealing caps used in sterile products. The first production stage is the mixing of rubber with additives and chemicals to form strips of base material, which are then coiled. The composition of this base material is dependent on its later application, and is prepared to customer specifications.
Two production lines of 12 thermoforming machines each cut the base material strips to size automatically. The trimmed sections are then pressed into a mould under vacuum, after which the individual components are stamped, vulcanised, tested, washed and packed.
The moulding process uses 24 moulding machines and takes place under high mechani- cal pressure, at temperatures between 175 °C and 180 °C, and in a vacuum of 1 mbar. Currently, the Busch vacuum system supplies half of the machines, though plans to expand the system have been approved and should be implemented during the course of 2016.
DPP’s moulding machines were originally equipped with oil-lubricated rotary vane vacuum pumps, though after a period of time, the pump oil reacted with the process vapour, causing emulsions and greasy deposits to accumulate in the vacuum pumps.
The deposits reduced the vacuum output, which impacted on the required vacuum level and pumping speed. Costly and inadequate measures to keep the pumps running were attempted, including changing the oil every two weeks. In 2009, DPP signed a maintenance agreement with Busch, in which Busch agreed to carry out third-party servicing of the vacuum equipment.
Following the maintenance agreement, Busch specialists studied the pumps and moulding equipment. In 2011, Busch presented a recommendation to replace the oil-lubricated rotary vane vacuum pumps with dry screw technology to DPP’s Montegaldella maintenance manager, Alessandro Piccoli. He then requested that a test system using the Cobra screw vacuum pump be commissioned.
The test system proved satisfactory, demonstrating that, as the dry screw pumps operate without compression fluids, there is no contact between the extracted vapour and any other medium in the vacuum pump. Moreover, the test system demonstrated that the pumps can run at a working temperature, allowing vapour to pass through the pump without condensing.
Following the successful trial, Piccoli ordered two Cobra vacuum pumps to supply a line of six moulding machines. Both pumps incorporated Busch’s Panda Roots vacuum pumps as boosters. This arrangement permitted the vacuum system to be installed away from the production buildings, with vacuum for the thermoforming machines supplied by a pipework system. An upstream vacuum reservoir ensures that the required vacuum level and pumping speed are constantly available.
In 2012, two additional vacuum units were ordered and installed – also with Panda Roots booster pumps – to supply a complete line of 12 thermoforming machines.
All the vacuum units are equipped with a fully automatic control system, which monitors the vacuum level and activates the minimum number of vacuum pumps required to meet the demand from the 12 thermoforming machines.