Automatically Leveling out Dosing Fluctuations
New Functions for Reducing Material Costs
The fear of falling short of the necessary minimum quantity when dosing additives means that, in practice, the prescribed dose is often exceeded. Instead of 5% color additive, 6 or even 6.5% is therefore used in production - i.e. around 20 or 30% excess. Such a massive overdosage, given a price of EUR 2.80 per kg additive and a material throughput of 50 kg per hour, adds up to about EUR 11,000 per year.
To avoid this and also maintain the product quality, the Gravimax unit have dosing functions that respond immediately to fluctuations in one component and compensate the other components so as to return to the sought-after ratio.
The touch interface of the Gravimax control allows different material grades to be selected in the course of production preparations, and to be saved in the control system. The control system differentiates between three material grades: virgin material, regrind and additive.
Dosage Mode “Reference Additive”
If an exact quantity of additive has to be added, the “reference additive” dosage setting can be chosen. This is also useful for avoiding color fluctuations and high material costs.
If severe vibrations on the machine or sudden shocks then lead to deviating amounts of additive being metered, the dosing unit instantaneously adjusts the amount of virgin material to be dosed to that of the additive. In the event of overdosage of the additive, the dosage of virgin material is increased, so that the percentage ratio of the two material grades meets the specification again.
Dosage Mode “Reference Virgin Material”
An exact dosage operating usually proves particularly difficult when plastics are used that are reinforced with long glass fibers (LGF). On one hand, the correct proportion of LGF-containing material always takes top priority; on the other hand, there is a greater risk of bridging of the material. To counter this effect, Gravimax dosing units are equipped with pulsating metering valves. LGF are thus kept moving during dosage.
And the effects of overdosage - in this case of virgin material - can once again be countered with the “reference virgin material” dosage mode This setting ensures that – depending on the actually metered amount of LGF virgin material – the amounts of further components can be adjusted accordingly.
Wittmann Battenfeld GmbH
Patents encourage innovation: Stay on the ball with the latest innovations in the plastics industry in our patents section.
Would you like to subscribe to our Newsletters on plastics technology and profit from the latest information?
You know the trade name but want to know the material manufacturer, type of polymer and delivery form? Search here!