As the pharma industry evolved the need of automated and integrated lines (filling – freeze-dryer) grew worldwide. In the recent years close to 80% of the pharma freeze-dryers are connected through direct conveyor to the automatic loading system and filling line.
After different steps (washing, sterilization etc.) a module fits the filled vials with a rubber stopper as a seal. The stopper is pushed in fully for liquid products but only part of the way for freeze-drying products: a sensor system will check that the stopper is present and that it is inserted to the correct depth. Incorrectly sealed vials will be rejected.
Depending on the format chosen, the vials are either fed into the loading and unloading unit of the freeze-dryer or—in the case of products that are sold in liquid form—transported directly to the capping machine.
If freeze-drying products are processed, the filled vials are arranged into rows in the loading and unloading unit and these rows are pushed into the freeze-dryer in a hexagonal formation so that the freeze-dryer can be loaded with maximum possible use of the cooling surfaces.
After the freeze-drying process the vials are again removed in rows and fed into the capping unit on the line.
Seems quite doable and easy tracking! In reality, there are major challenges in establishing the right connection between the filling line and the freeze dryer. LyophilizationWorld has interviewed several engineers to dig into the most important aspects to consider and below are gathered the 3 most challenging subjects.
Synchronization
Synchronizing vials in a conveyor system into the loading system bridge is an enormous challenge in and of itself.
To add difficulties, the two systems involved are generally designed by two different companies: the loading system from the freeze dryer manufacturer and the filling from the packaging equipment manufacturer. Even, in those cases that the manufacturer is unique the two systems come from different previous companies (prior to acquisition) or teams.
The timing and the flexibility of adjustment is key in matching a continuous machine - the filling line – and a step by step (or better row by row) one.
One possible solution is the use of a star-wheel for vial control, which acts as a counter, stop/start gate and in conjunction with the marshaling conveyor places a row of vials in front of the loading bar.
Flatness
Another important aspect to ensure a long-lasting line is the mechanical adjustment of the loading system plate over the conveyor and the freeze dryer shelf: the 3 surfaces must be perfectly aligned in order to smooth the movement of the vials in and out the freeze dryer (with no falling or tough grazing).
Layout
This point goes along with the difficulties of having more manufacturers involved. In this case it might affect another important area of the production: Containment!
The responsibility of the layout should always fall under the freeze dryer manufacturer ownership. The reason being that the FD is the most complex equipment, the bulkiest and generally the most expensive.
Very important are 3D modelling and for the production the use of dummy plates.