Injection molder comes clean

by Mark A. DeSorbo

Medical product manufacturer gets cleanroom-specific injection molding systems for controlled environments

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Createchnic AG had been manufacturing injection and injection-blow molding machines for 18 years when it hatched plans to produce container, dosing and application systems under cleanroom conditions for the pharmaceutical and medical industries.

Createchnic operates its injection molding systems in cleanrooms, manufacturing products for the pharmaceutical, chemical and cosmetics industries. The company, however, mainly produces medical technical products, ranging from complex packaging units with dispenser systems and disposal medical products for cardiology and orthopedics to resorbable human implants.
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Like injection molding, manufacturing products such as orthopedic and cardiological human implants requires distinct techniques, including plasma treatment and thermoforming, not to mention gluing, welding, assembly and packaging of plastic parts.

That's when Createchnic turned to Dittel Cleanroom Engineering, a Benediktbeuern, Germany-based firm, to construct an addition and cleanrooms.

Dittel outfitted the manufacturer with cleanroom-specific injection molding systems as well as controlled environments, including ISO Class 8, ISO Class 7 and ISO Class 5 (Class 100,000, Class 10,000 and Class 100), thus expanding the production facility by 2,500 square feet. “Next year, Createchnic wants to build another addition about the same size,” says Gernod Dittel, chief executive of the cleanroom engineering firm.

Project feasibility

According to Dittel, the area had to be integrated in an existing infrastructure, while the cleanroom facility had to comply with ISO 14644 (Fed-Std-209E), GMP standards and have the approval of the U.S. Food and Drug Administration.

Dittel first conducted a project study to determine if required cleanroom engineering would be sufficient and if the existing infrastructure could pose problems. After analyzing the building's condition and existing technology, Dittel determined that a standard solution would not do and back assembling of the existing and installed process facilities would be difficult. The project study also evaluated product specifications to define possible solutions to derive various facility versions to determine the best design.

Altogether, five proposals were presented, each designed for a facility with ISO Class 8, 7, 6 and 5 cleanrooms (Class 100,000, 10,000, 1,000 and 100). The arrangement and assembly of the air conditioning equipment, the air-feed in the cleanroom, granulates drying, technical media equipment and things such as the laying of the tubing system were taken into account. The project study was also used to determine the most favorable combination in terms of architecture, energy and costs, which would also ensure product-related threshold values for air cleanliness with respect to particles as well as bacteria.

Along with the project study, Dittel recommended that a qualification plan be set up at least by the time Createchnic gave the go-ahead to begin site work.

Cleanroom infrastructure

Product-related quality requirements have a considerable influence on the infrastructure of the cleanroom as well as the concept, room classification and the maximum allowed particles or germs.

In addition, the safety and stability of the facility in terms of air exchange rate and pressure levels as well as precautions against electrostatic charging were concerns, Dittel says.

For injection molding manufacturing and in-process control, a single box with process exit air was selected as suitable room concept. Final testing and packaging in primary and secondary packaging (without labels) is carried out in a separated part of the cleanroom facility. The cleanroom class was defined with Class 7. That classification was derived from the sterilization method (gamma radiation from one Cobalt 60 source) and it reflects what is technically workable in injection molding manufacturing.

Production process

In this new facility, polymer materials were custom molded to various products, including bio-resorbable interference screws, inhalators, one-way syringes, blood bags, infusion tubes and parts for dialysis facilities and for artificial hearts.

When processing plastics under cleanroom conditions the main point of emphasis is directed at dust, of which humans are the greatest producers. Dust particles produced by human activities, according to the project study, are in fact, smaller than 0.5 micron however they accumulate in great quantities. Dust particles greater than five microns are not much of a threat, because they can be removed by appropriate cleaning procedures.

The production process was divided into 13 steps starting with entry testing of the raw materials up to the delivery of the finished items. The majority of these steps are carried out in cleanrooms.

Raw materials are first brought into a Class 8 cleanroom for storage or before transportation. Preparation of injection molding tools, actual injection and drying stages are conducted in ISO Class 6 (Class 1,000) cleanrooms. In-process and final tests are completed in Class 5 cleanrooms and products are packaged in ISO Class 6 cleanrooms.

Products that are repackaged under “gray room conditions” undergo bioburden examinations in laboratories and are sterilized with gamma radiation from a Cobalt 60 source. The products are then checked for endotoxins and for overall sterility.

Tooling challenge

Few toolmakers are able to manufacture cleanroom-suitable injection molding tools properly, Dittel points out.

The main difficulty is that lubricants are not supposed to be used. If they are, the lubricants must not get anywhere near the work area—they must be directed inwards with the help of an appropriate differential pressure.

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What is allowed for ejection movements are air cylinders supplied with cleanroom air. The ejection itself, however, should not be done with air support. Stripping devices are available that are either operated mechanically or with air cylinders. The forcibly actuated, mechanical method is better and safer because it ensures a controlled ejection.

Should a preform stay put in the tool and be crushed during the next preforming, the tool must be completely cleaned. Waste should be avoided, using a pinpoint gate.

Hot runner molds are not always appropriate because the nozzles are not always 100-percent leak proof. The consequence is often contamination due to liquefied material or gases. The changing of tools involves great efforts in cleanroom manufacturing, especially in ISO Class 3 (Class 1).

At first the new tool must be completely disassembled and cleaned under cleanroom conditions. Quite suitable for this purpose is a laminar box in which assembling can be done. After that the tool is either welded three-fold in foils or packed in a special transportation box. The outer foil is removed in the pre-chamber of the cleanroom. The second cover is removed in the transfer lock to Class 6; the inner, third cover is first removed at the machine.

Depending on each particular case and the regulations, the preforms may fall out of the machine freely or they must be taken out. A Class 3 cleanroom production requires a handling device for taking out preforms. Despite special clothing and all precaution measures, the operating personnel are always the greatest creators of dust and dirt.

Suitable for collecting the preforms falling out freely are special gas-proof lock-up containers, or gas-proof bags or tubing systems. If bags are being used, Dittel recommends using three bags stacked into one another. Before transporting into areas outside of production, each bag must be welded separately. Tubing systems make sense if the parts are lead directly to the further-processing facilities. These facilities must heed to the same rules and regulations as is required of injection molding machines.

Key facts

Size of the expansion: 2,500 square feet, with an additional 2,500 square feet of manufacturing space planned for next year.
Purpose of facility: To manufacture medical products such as cardiological and orthopedic implants.
General contractor: Dittel Cleanroom Engineering (Benediktbeuern, Germany)


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