The TOP 5000 P mixing and dosing equipment introduced by Oftering, Austria-based Elmet Elastomere Produktions- und Dienstleistungs GmbH at the Fakuma fair featured a new touch control panel and a system of labeling each of the two LSR component drums with letters A and B, to help prevent production disruption due to incorrect drum connection.
But the system offers more, as it can handle a large range in amounts of colors and additives with high precision, as LSR World recently learned. It talks of typically 10 percent addition, with 20 percent sometimes used, while customers are known who apply as little as 0.02 percent additive to LSR.
Dosing precision is ensured with externally produced volume meters exactly determining the amount of LSR base material, LSR flow being recorded with 64,000 increments per liter. This is also the rate for recording low amounts of additive flow at fine resolution — just several grams shot weight is typically required for 2 percent color content. Most additives known by Elmet to be applied with its equipment are for coloring, but oils, medicinal agents, or conductive additives are sometimes also involved.
Elmet has addressed agglomeration and contamination risks when mixing additives into external drums, now providing for critical applications a container for additives and colors fitted with a permanently moving agitator and a fine filter and clamped onto the equipment — a claimed better solution than conventional turning or shaking. The agitation system is available on a 20-liter container.
Additives and colors previously needed mixing directly in a conventional drum and this has been known to lead not only to separation and agglomeration of drum constituents over time, but also to risk of contamination during external mixing.
The dispersed additives/colors are fed into the LSR material flow for static mixing, then dispensed via a displacement principle valve for dynamic mixing in the injection molding machine screw. Homogenous well-dispersed additives/color mixtures are needed for precise metering.
Aside from agglomeration and separation issues, TOP 5000 P compensates for material volume reduction due to contamination, so that the set addition percentage is always achieved. An orange light alarm is set off when a deviation threshold has been reached, and a message calls for maintenance if the deviation level continues to increase, followed by system shutdown if a fault limit is exceeded.
Elmet's new additive container system can be retrofitted to Elmet machinery using controllers supplied since 2014. Several additive and color dosing units can be operated simultaneously, one regulated, but parallel application of two regulated dosing lines has been developed meanwhile.
The company prefers pneumatic rather than electric drive, saying, "It is the control system, not the drive, that is crucial for process stability." Elmet states furthermore, "high process stability means less color, but more intensive color" with color producers saying it can save up to 20 percent of annual color costs.
Elmet rules out electric drive use in Elmet mixing and dosing systems, saying low energy cost of, for example, 300 euros ($341) per year when producing 20 metric tons per year "does not justify dispensing with the advantages of the robust technology and the reliable spare parts supply over the entire product lifetime."
At Fakuma 2018, Elmet claimed to be the first LSR mixing and dosing equipment producer to use an Open Platform Communication Unified Architecture (OPC-UA) interface between injection molding machines and LSR dosing systems, enabling TOP 500 P "to communicate and exchange data in real time machine-to-machine [M2M] with injection molding machines."
Elmet developed the LSR processing OPC-UA solution with Schwertberg, Austria based injection molding machine producer Engel Austria GmbH and it is due for introduction on other producers' molding machines too.
It means LSR processors can now save recipes and process parameters directly with injection molding machine data, and set and change dosing parameters via injection molding machine control panels. It also facilitates incorporation of dosing data within a production plant's overall manufacturing execution system (MES).
Also new at Fakuma 2018, Elmet introduced a Shore-Mix version of the TOP 5000 P that enables two "A" and two "B" drums to provide different mixing ratios for a wider Shoe hardness choice.
