The principle of clean room operation is that factors that reduce cleanliness must be thoroughly eliminated from the clean room.
However, in the case of plastic molding for medical use, production in a clean room is inevitable, so it is necessary to install injection molding machines and its auxiliary equipment in the clean room.
Therefore, it is necessary to take measures against equipment that impairs cleanliness in the clean room.

１．Plastic injection molding machine

Cleanliness is reduced by the gas generated from the hot resin. In plastic injection molding, it is necessary to purge before starting molding to discharge the resin that has accumulated in the cylinder of the molding machine. However, this operation significantly reduces the cleanliness in the clean room. As a countermeasure, it is necessary to install a device at the portion for the purge to discharge generated gas outside the clean room.

２．Maintenance of mold

In plastic injection molding, daily mold maintenance is required to maintain product quality, mold durability and mold life.
However, some of the cleaners, lubricants, rust inhibitors, mold release agents, etc. used for mold maintenance reduce the cleanliness in the clean room.
As a countermeasure, when performing mold maintenance, move the mold outside the clean room and perform mold maintenance. When performing mold maintenance in a clean room, wipe the mold with alcohol instead of spray-type lubricant or cleaner.

３．Exhaust from plastic injection molding machines

Plastic injection molding machines are equipped with a number of fans to remove the heat generated by themselves. If dust or dirt accumulates in the plastic injection molding machine, the fans will blow up the air and spread the dust or dirt in the clean room. It is important to clean the inside of the molding machine every day, especially for fans where dust and dirt easily accumulate.

４．Plastic materials

When bringing plastic raw materials into the clean room and supplying to plastic injection molding machines, the cleanliness reduces. There are the following two factors.

①Bags for plastic raw material and plastic raw material itself
Most bags for plastic raw material are paper bags, and paper causes a reduction in cleanliness. In addition, the plastic raw material itself has fine powder attached, and there is a risk of lowering the cleanliness level at the time of use.
As a countermeasure, the material tank is installed outside the clean room and is supplied to the hopper of the injection molding machine using the material supply device.

②Material supply device
The plastic material is supplied from the material tank to the hopper of the plastic injection molding machine by the material supply device. The exhaust of this material supply device reduces the cleanliness in the clean room. A HEPA filter is used for the filter of the material supply device to prevent a decrease in cleanliness.