How clean is your equipment?
July 1st 2006

Ensuring that your production lines remain clean and free from dirt is essential to reduce waste says John Penman, managing director, Microclean Technologies

Dust and static contamination is not a glamorous subject but is one that industry needs to take more seriously. Dust, static and other contaminates can severely affect any production process by increasing waste and lowering end of line yields. Ultimately this affects profitability.

There are a number of causes which result in surface contamination but three key factors are machines, people and the material being processed. For example, inline slitters create slivers and dust particles, operators contaminate through skin flakes, hairs and clothing fibres, web materials and sheets generate static which attract dust particles as they are unwound or separated.

Surface contamination can affect all kinds of production processes. The bottling and packaging production industries in particular face this hidden problem which was addressed many years ago by the medical and pharmaceutical sector. Medical equipment and drugs are packed under the most sterile conditions but can the same be said of the food and drink sector?

Obviously it is uneconomic for food and drink manufacturers to invest in the type of clean rooms used in medical packaging and the electronics sectors. However, they need to be aware of the dangers of dust and other debris entering the food packaging and bottling production line. There are two key issues to be addressed. The first is dust and other particulates getting on to the packaging materials which can then contaminate the food contents. The second is static which is created whenever materials such as film or paper move over rollers and so forth. This static attracts dust which can not only contaminate the packaging but if particles get trapped in the seal it will not be airtight. This can severely affect yields as such packaging will have to be destroyed.

Furthermore, static and dust can affect the labelling of products. If the surface is not clean when screen printing on a bottle, for example, it can affect the print quality. Likewise static can mean that labels are not positioned properly as the static charge on a plastic bottle can effectively 'push' the label in a different direction resulting in a misplaced label and wastage.

There are also health and safety issues. Products such as shampoo that may have alcohol or other flammable vapours, can ignite if an ESD (electrostatic discharge) generates enough energy in the filling station area. Static cling electromagnetic attraction or repulsion caused by static charge can cause the liquid or product being dispensed into the bottle or container to behave incorrectly so that the tail or last drop of product can be attracted to the mouth of the container causing aesthetic issues or even a seal failure. Also the product can have excessive air bubbles due to static attraction or repulsion to the container itself.

Specific industries such as cosmetics have to take particular care with dust and static problems. In this sector appearance is everything with up to 90% of the production costs being spent on packaging. A human hair or eyelash in a lipstick case or a black spec of dirt in a clear bottle of perfume, if it manages to pass through quality controls, can severely impact on sales.

Another industry which needs to ensure its production environment is scrupulously clean is the electronics (PCB, SMT) coating and converting sector. If SMT boards have traces of dust, loose surface particles or static before screenprinting, this can result in blocked adhesive nozzles, reworking, reduced end of line yields and frequent underside stencil cleaning.

So what solutions are available? To remove static, static neutralisation bars and ionised blowers should be integrated into the production line. This will ensure that not only are materials such as film static free but it can also help eliminate jams by removing the tendency for sheets of film to cling to each other.

Vacuum systems can be used to effectively remove dust from form and fill packaging by removing the particulates before the contents are put into the container. Another method is to blow ionised air using an air nozzle into the container to evacuate the particles and the particles are then captured using a Webvac system and disposed of. A Webvac system will also filter the ambient air to remove particles so there is less risk of recontamination.

Contact cleaning systems can also be used to ensure that dust and other particles are effectively removed from the materials before they enter the production line. Possibly the best overall solution is a two-step contamination removal process. This uses a special elastomer roller to remove contaminants from the product's surface down to one micron in size. The contaminants are then transferred on to a roll of adhesive film for disposal. The second stage involves passing the product through anti-static bars to avoid recontamination. This equipment can easily be installed "in-line" and the replacement of consumables is quick and easy.

The key benefit of having a production process free of static and contaminants is reduced waste, higher yields and ultimately higher productivity and profits.

Microclean Technologies and its US partner Static Clean International specialise in contact cleaning and static neutralisation solutions for a wide range of industries including packaging, bottling, labelling, cosmetics, printing, pharmaceutical/medical and electronics.