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March 8, 1999

3 Min Read
Moulding Under Cleanroom Conditions

Cleanroom production does not necessarily mean dedicated space and high costs. If you need a clean environment, but don't require the level of a dedicated cleanroom that might be needed for medical products, for example, you might be able to transform a regular injection moulding machine into an efficient and effective production cell under cleanroom conditions. Robert Naville, of machine manufacturer Fahr Bucher, Gottmadingen, Germany, explains how to achieve this, step-by-step, for a moulder of packaging.

Plastic packaging and packaging parts are extremely demanding parts to manufacture. First, the parts are usually required in large quantities. The injection moulding cell—the moulding machine, mould, and parts-handling peripherals—must permit reliable large-lot production. Second, packaging parts ordinarily have very thin walls. Third, clean production is important, since it saves on expensive, time-consuming and environmentally polluting cleaning procedures before filling.

Cleanroom Production in Steps

The basic structure of injection moulding machines permits the entire mould area to be kept free of contaminants. Figure 1 shows a concept for the production of low-contamination parts, which can be expanded step-by-step and extends from the basic machine design and a mould area free of contaminants through to cleanroom production.

Because of the projecting clamping unit, all the sources of contamination at each step of expansion are at the right of the platen. Only the ejector actuator is mounted on the movable platen. Even this risk of contamination can be completely eliminated by encapsulating the actuator, whether the ejectors are hydraulically or electrically operated.

In conventional injection moulding production, the hydraulic components, electric motors and material feed are the main sources of contamination. In the simplest solution (view A), where parts are dropped directly into cartons, the mouldings can be contaminated by dirt from production and additionally by cardboard fibers. A simple cover over the mould area, combined with a removal and stacking device (view B) reduces the contamination of the parts considerably.

If, in the next step, the mould area is completely separated from the area of the machine and its supply lines (view C), all important sources of contamination are excluded. Packaging manufactured under such conditions no longer requires any cleaning that might pollute. Where it is used for slightly perishable foods, it may be necessary to sterilize with UV light or irradiation.

In the final step, the clean operating area of the previous step can be developed into an actual cleanroom that meets the required class of purity (view D). Since the cleanroom is relatively small and contains no critical sources of contamination, the total expense is relatively low. The machine can be mounted on rails, or if necessary, on air cushions, in order to remove it from the cleanroom for mould exchange and maintenance work on the mould or the clamping unit. In this case, a shield on the movable platen seals off the cleanroom.

In view of the generally high technological level of the injection moulding process, isolated individual measures provide at best a short-term improvement in economy. Long-term success can only be achieved with a production system in which all components are matched to one another.

Contact Information
Fahr Bucher
Mr. Robert Naville
Gewerbestraße 31
D-78240 Gottmadingen
Phone: (49) 7731 904-0
Fax: (49) 7731 904-160

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