Cold-Half Core-Centering Technology for Blood-Collection Tubes

SIPA has spent several years developing new injection mold tooling solutions specifically for medical applications, encompassing wide cell culture containers to deep and narrow blood collection tubes (BCTs). Based on this work, it has developed a cold-half core-centering technology that it developed for BCTs, which it says is already being used successfully at a leading global supplier of the tubes.

SIPA’s patent-pending technology allows molders to adjust the core alignment from the front face of the cold half instead of requiring access the back of the core plate, making adjustments easier and faster to carry out during production.

Production of high-quality BCTs requires the wall thickness around the circumference to maintain very tight tolerances. SIPA notes that the same is true with more common PET products like bottle preforms, but adds that maintaining consistently uniform walls over long-term production is more difficult to ensure with BCTs.

This is due to the fact that BCTs have a much smaller diameter than regular preforms, which also reduces the dimensions of the various components of the mold. In particular, the small diameter of the cores leaves them more susceptible to deflection during injection, especially with the relatively high injection pressures required for BCTs. SIPA’s solution makes it easier to fine-tune the positions of the cores, correcting even small deviations from the set value.