No Shocks at Primopost

When a material holds a net electrical charge, either positive or negative, it is said to have a static charge. The term static is relative as in many cases static charges will slowly decrease over time. The length of time this takes is dependent on the resistance of the material. For practical purposes, the two extremes can be taken as plastics and metal. Plastics generally have very high resistivities and this allows them to maintain static charges for long periods of time.

This can cause big problems for companies such as Primopost. A supplier of high quality plain and printed film substrates for the packaging industry, it also provides a contract service for slitting, rewinding, flexo printing, and coating.

Not only does static cause production quality problems such as poorly wound reels (which can be difficult to fit on to customers' machines and may cause feed problems) and dust attraction (leading to contaminated stock), but it also has enormous health and safety implications. This is becoming increasingly significant as companies look to improve safety standards.

While shocks can be painful, the effects are usually quite safe and short-lived. However, in extreme cases, receiving a shock can result in personnel becoming disorientated, bringing with it other hazards such as collisions with both other operators and machinery. There is also an increased danger of sparks that can cause explosions and fires in hazardous areas.

Serious

At Primopost production director Rob Donaldson takes the problem of static very seriously. "We run six slitter rewinder machines, all of which are fitted with anti static systems. We run our films at speeds up to 600m/min and static control is imperative. Our aim is to supply plain and printed packaging materials 'static-free' to our customers and that we are confident they can run these films with no problems. However, as static is induced at the point of separation, we also advise our clients to install static control systems."

Reducing static

Slitting machines have complicated static problems on the winder. The usual solution is to attack the charge with a Pulsed DC bar, such as the Meech Model 976. This is a special product that has been designed to provide highly effective long range ionization up to distances of 600mm and greater. It is both shockless and easily maintained.

This method works on the principle of producing ionized air by using high voltage. The bar comprises a series of emitters connected alternately to the positive and negative outputs of a DC controller; in Primopost's case the Meech Model 977v3. A statically charged object in the vicinity of the bar will attract or repel the ions and when they reach the object, neutralization will take place. This system enables the operators to adjust the ion balance and output frequency manually to give optimum ionizing efficiency.

Seeking to improve on existing methods to give added value to its customers, Primopost was very interested In the Meech development of a new system (the Model 986 Feedback) In which the various controls were adjusted automatically.

The entire system consists of a feedback sensor and controller in conjunction with the Meech 977v3 Pulsed DC controller and 976 ionizing bar. The system controller automatically adjusts the ion output balance by communicating with the sensor and ionizing bar. This ensures that the static control system can operate at optimum performance under a range of conditions, without operator intervention. An illuminated digital display shows the adjustments and provides confirmation that the antistatic is working. Alarm outputs have also been included for remote data logging and records management.

A trial system was retrofitted on one of Primopost's existing slitter rewinders and proved so successful it is now permanently installed. A new Titan SR7 slitter rewinder has also been commissioned by Primopost and is fitted with a full Meech Pulsed DC long range anti static system including the 986 Feedback. It is intended that all new machines will incorporate this system.