Medical moulding

Bespak recently completed the final phase of what has been a £55m investment at its site in King's Lynn, Norfolk. The new £10m 1,400m2 cleanroom has been designed to support the precision manufacture of pressurised metered dose inhaler (pMDI) valves used in the treatment of respiratory illnesses such as asthma and chronic obstructive pulmonary disease (COPD). While it provides a pure manufacturing environment in every sense, the development of Bespak's new facility was not without its challenges. The overall strategy was for the transition to a new manufacturing facility to be completed without affecting customer expectations or compromising the existing high standards of operations. Modestino Graziano, programme manager at Bespak, led the project supported by a cross-functional internal management team. "Although we were given a blank sheet of paper, there were very real constraints which had to be observed," he explains, "not least the fact that production commitments had to be maintained throughout the reconfiguration of the host building." According to Graziano, there were several key components for the strategy: 1. Optimise workflow – single line of operation throughout 2. Terminate half in/half out configuration for pMDI manufacturing to ensure optimum cleanliness and eliminate airflow disruption in the cleanroom 3. Create a cGMP compliant facility with pristine lines and design features to eliminate the normal paraphernalia associated with moulding and assembly operations 4. Consolidate all pMDI operations into a single facility 5. Increase moulding and assembly capacity for new product variants

These aspirations had to be reconciled with a number of constraints faced by the team:

• Transferring existing tooling technology into the new facility
• The Granulation process
• Handling waste from the granulation process
• Performing the granulation process inside the new facility
• Maintaining the historical levels of particulate compliance
• Supplying materials to moulding and assembly equipment
• The host building had constraints on three sides and, of this space, 50% was being occupied by existing production activity that would have to be maintained throughout the reconfiguration of the host building.
• Tooling which had been approved on a hydraulic moulding platform

Bespak introduced a number of key initiatives that would drive innovation:

• Create a large hall with all processes within the boundaries of the facility
• Reconfigure/move ancillary areas to facilitate optimum workflow
• Redesign the granulation process so as not to adversely affect the particulate compliance as measured against the existing granulation process (which was then outside the cleanroom)
• Re-approve all pMDI tooling on a different moulding machine platform
• Use the height of the building to advantage for the provision of service requirements to moulding and assembly equipment

While Bespak worked through all these different challenges this article deals with the granulation issues the project team faced, Tony Fleetwood, Technical Project Manager took responsibility for developing a new granulation process. Fleetwood says the team needed to develop a solution to ensure existing levels of particulates were maintained in the new facility. "This meant having to model the impact of the granulation process before it was introduced into the new facility. Getting this wrong would mean not being able to satisfy the minimum particulate compliance level, which would halt pMDI valve production," he adds. Bespak set out to study particulate levels attributable to the granulation process. Trials were carried out over a 12-month period, prior to construction of the hall, to assess particulate levels around the granulator chute. The work examined particulate levels throughout the manufacturing cycle over several months of operation. The data was then analysed and a number of assessments were made regarding the viability of introducing the existing process into the new facility. Fleetwood continues: "The team knew that if the current granulators were simply moved into the new facility, particulate levels would be adversely affected. We knew we had to radically re-engineer the granulation process." Bespak invited several suppliers to tender proposals for a cleanroom granulator, however none satisfied the company's needs. One supplier, Rapid, did suggest working jointly to develop a bespoke machine. Following full experimentation, a Rapid cleanroom granulator was finally approved. It incorporated a number of innovations:

• Scavenger system A unique airflow system that employs a pump to extract fumes, heat and particulates.
• Co-ordinated buffers Two stainless steel flaps replace the previous single-flap system to create a transgression chamber that confines particulates during operation. The buffers are linked to the plant level controller and recognise a signal from the mould tool which triggers them to open and close in co-ordination with the scavenger system to reduce particulate contamination.
• Stainless steel casing The granulator is fully insulated in a stainless steel surround to ensure any material that escapes from the catchment box is completely contained. It also reduces temperature and noise pollution.
• Alignment guide A locking mechanism that ensures the granulator is always located into the correct position for the top seal to engage to the chute.
• Purge function A purge function to evacuate the granulate catchment box.
• Guarding modifications Design changes to the moulding machine guarding were made in order to provide an excellent seal between the moulding machine and the granulator.