For the freeze-drying process, due to the changes in temperature and pressure during the process, the cladding material (Xilin bottle) will be affected by forces, which makes the crushing of Xilin bottle an unavoidable quality problem. It not only increases production costs and waste, but also causes particle contamination in sterile production.

Based on a freeze-drying process in which the temperature varies from -40 ℃variation to 35℃ and the pressure varies from atmospheric pressure to 1 Torr, this paper compares and analyzes complete (8 Good vials) and damaged (8 Bad vials) 10ml controlled freeze-dried sirloin bottles, and attempts to discuss which differences in packaging material variables can easily lead to bottle breakage in sirloin bottles during the freeze-drying process.

Bottle opening diameter:

Measure the aperture of the bottle mouth of intact and broken Xilin bottles using a pass-stop gauge. Using a pass/stop gauge on broken bottles, I found that none of the broken bottles fit this gauge (as shown in Figure 2 below). Because the average diameter of the mouths of all broken sirloin bottles was Average diameter = 12.45 mm, while the average diameter of the mouths of intact sirloin bottles was Average diameter = 12.54 mm.

Conclusion 1: Cillin vials with a small mean pore size (12.45 mm) ruptured, whereas vials with a large pore size reading (12.54 mm) remained intact, clearly indicating that small changes in pore size may be the cause of vial rupture. When the pore size is less than 12.54, as the steam generated by the steam pressure difference may not be discharged smoothly, the pressure in the bottle is increased.

Bottle bottom thickness

The bottom thickness of the sample bottles in the experiment was measured using a self-made measuring table, and the bottom thickness of intact and damaged bottles was measured. The bottom thickness of intact Xilin bottles ranged from 1.05mm to 1.30mm, while the bottom thickness of damaged bottles ranged from 1.38mm to 1.77mm.

Conclusion 2: Thickness calculations showed that the bottom of the broken Xilin bottle was thicker than that of the intact bottle, and heat transfer from the thicker bottom generated more thermal stress, which may be another potential cause of Xilin bottle rupture.

Bottom contact area of the bottle

The bottom of the Xilin bottle sample was indented and drawn on drawing paper, and constant force pressure was used to ensure uniform marks. The bottom of the bottle was examined with a blue imprint, and the contact area was calculated using the mean diameter method (AVG). As shown in the following figure:

Based on the above calculations, the average area of a good Xilin bottle was found to be 1.8289975 cm2. The average contact area of the damaged Xilin bottle was 0.9557675 cm2. The contact area of a broken Xilin bottle is much smaller than that of a complete Xilin bottle.

Conclusion 3: The smaller the contact area at the bottom of the bottle, the greater the possibility of rupture of the Xilin bottle. Studies have shown that the bottom of the Xilin bottle plays the main heat transfer role in the freeze-drying process. The larger the contact area, the smaller the chance of the bottle body cracking. There is a large temperature difference between the bottom areas of the bottle in the contact and non-contact parts, which may cause uneven shrinkage and generate stress.