Development project TELC in collaboration between the companies Gerresheimer Bünde GmbH and Braunform GmbH

The closure system for pre-filled syringes - TELC. (© Gerresheimer Bünde GmbH)

Each cavity is individually handled with a process patented by Braunform. (© Braunform GmbH)

The experience of 35 years of mold making at the highest level and a profound understanding of the pharmaceutical market form the basis for customer trust in Braunform GmbH. In close collaboration with Gerresheimer Bünde GmbH, the development project TELC was launched. TELC stands for “Tamper Evident Luer Lock Closure,” a closure system with authenticity assurance for pre-filled syringes. The innovative closure is injection-molded from two components within a single injection molding process and meets the highest requirements in terms of design, material selection, mold making, and production conditions in a cleanroom environment for plastics manufacturing.

An engineering innovation of the series tool is the dust-free, low-particle unscrewing of the Luerlock adapter and the low-particle shearing of the sprue after the injection process. Due to the delicate contour for the authenticity seals, which indicate the first opening of the closure, very thin, free-standing cores are used. A specially developed needle closure hot runner system for the cap, operated via an inclined plane, is also employed. Other technical challenges include the wall thickness of the cap, which must be screwable with a defined torque, and the clean separation of the contours of the two components.

Prior to the 16+16 cavity two-component injection molding tool with a rotary table, a series-like pilot tool was used to minimize risks. The special material pairing of the pharmaceutical primary packaging involves a significant temperature difference within the tool: on one side, the Luerlock adapter is molded from high-temperature resistant and tough polycarbonate (PC) at around 100°C, while on the other side, the screw cap with authenticity seals made of thermoplastic elastomer (TPE) is molded at 40°C.

In addition to temperature and high pressure, the challenge in processing the hard/soft connection is that it must not be chemically bonded and must also be sterilizable. To prevent burns and black spots during processing of polycarbonate, the manufacturer's specifications must be strictly followed.

Due to the critical material selection, the TELC is injection-molded in its own production cell under ISO Class 5 cleanroom conditions, with each cavity individually handled using a patented process. Subsequently, the customer-specific rubber seals are installed during the assembly process.