Mixing and dosing made easy

Application-focused resin mixing has been made possible with the launch of new mixing, blending and dosing equipment with a wealth of optional features. The Uni tec and MTI Eco plus-line series featured at K 2013 by MTI Mischtechnik (www.mti-mixer.de) presents an innovative portfolio of energy saving, highly efficient systems for demanding mixing tasks in the plastics processing industry. The machines are complemented by a fully redesigned Vent tec aspiration system which removes moisture from dry blends during mixing and is noted for its exceptional operating reliability and uniformly high performance even under most difficult production conditions.

Designed as vertical-type systems, MTI’s Uni tec Universal Mixers are suitable for the preparation of plastics across a very broad application range. This starts with the homogenisation of bulk stock of widely differing characteristics and extends through complex process technology tasks required, e.g. in drying and pelletising specific materials. Thus, a single mixer may often combine multiple process steps in a cost-efficient manner where different equipment set conditions had to be employed before. A wealth of optional features enables MTI to realise application-focused custom configurations which are perfectly matched to their specific operating environment at the company’s own R&D Centre beforehand.

MTI’s Eco plus-line is the result of consistent upgrading of the MTI Eco-line heating/cooling mixer combinations launched at K 2010 which have since gained renown for their dependability and high performance in diverse practical settings thanks to requirement-based configurations and their elevated cost- efficiency. With the portfolio expansion now available, the demand for double-batch machines capable of mixing PVC-U for the volume production of products such as, e.g., pipes or profiles is fully met. Given their unsurpassed mixing characteristics and particularly good efficiency, these systems can deliver throughputs of well over 10 tonnes/h, allowing investment payback times to be minimised.

Mixer adapts to different process phases

Vent tec is a latest-generation mixer aspiration system developed by MTI with a special emphasis on improved performance under constant production conditions. The system adapts automatically to the different process phases which constitute the mixing operation. It can be employed with only minimal adaptations in mixers of almost any design and in virtually all ATEX ambient situations.

The continuous improvement of equipment’s efficiency, achieved by packing multiple functions into one system, makes for increasingly complex process workflows. As a result, the unit can be used to mix, homogenise and disperse raw materials of the most diverse properties, preparing them for a surface treatment and drying step in the same mixing system afterwards. The users will thus save energy and time.

Powerful gravimetric batch dosing system

ProTec Polymer Processing (www.sp-protec.com) introduced SOMOS BB500 dosing and mixing system also at K 2013. The system is suitable both for supplying injection moulding machines and extruders with multi-component mixtures. This batch dosing system is designed for a maximum of four free-flowing components and for throughputs of up to around 500 kg/h (at a bulk weight of 0.6 kg/l).

The system is mounted directly onto the material feeder of the processing machine – or onto a frame near the machine – and can be equipped with SOMOS? suction conveyors for automatic filling of the material tank. Ease of use is ensured by a touchscreen controller equipped with a graphical user interface (MH 45) specially tailored to the range of tasks performed by a batch dosing machine. Up to 50 stored, individual mixture formulae can be called up and used immediately. Another special feature is that the system can be equipped with a second weigh cell to enable it to take over throughput regulation of an extruder. The new SOMOS BB500 batch dosing system offers high dosing precision at an attractive price-performance ratio.

The individual components of a material mixture are dosed in sequence into a weighing hopper according to the recipe and the entire batch is then homogeneously mixed by a four-blade mixer in a mixing hopper below. The weighing hopper has a volume of 10 l, the mixing hopper a volume of 30 l. The respective discharge from the material supply hopper, weighing and mixing hoppers is equipped with pneumatically operated slide gate systems. To regulate the material flow into the weighing hopper, a reduction ring can be fitted to the discharge from the material supply hopper to reduce its diameter.

In addition, the cylinder stroke for opening the slide can be reduced with the aid of set screws. In this way, the SOMOS BB500 batch dosing system enables extremely cost-effective gravimetric dosing of even very small mixing proportions using slide gate systems, achieving precisions of ± 1 % up to ± 0.5 % of the dosing weight of the respective component. Quick releases and spacious access to the material containers and weighing area as well as removable mixer components enable materials to be changed very easily and quickly. The size of the material storage tank is freely selectable at all positions; hoppers for pellets as well as special hoppers for regrind, each with different volumes, are available.

The intuitive and powerful controller with a 6” colour touchscreen is included as standard in this high-quality design. The local memory in the network-enabled controller can also store and provide direct access to recipes and other data. A USB interface fitted as standard allows users to export recipes and data or import additional, externally stored recipes. If the mixing hopper, in addition to the weighing hopper, is also equipped with a weigh cell (optional), the controller of the batch dosing system can simultaneously regulate the throughput of an extruder supplied by it. The ability to control conveyors is also provided as standard: A conveyor for feeding the supply hopper can be allocated to each dosing component. To prevent the system operator from making unauthorized changes, the controller features two operating levels with password-protected access to the administrator level.

Clinically clean dosing and mixing system

Motan-colortronic GmbH (www.motan-colortronic.com) launched its Ultrablend 95 gravimetric batch dosing and mixing unit, which offers clear advantages to manufacturers of thermoplastic medical devices. The model has been developed for consistently precise dosing and mixing of free-flowing raw materials – plastic granulates and additives. It improves process quality and stability and makes its own contribution towards minimising production costs. With the design in electro-polished stainless steel, great emphasis was placed on clear functions, minimum maintenance and easy operation in a hygienically clean production environment. All material hoppers and mixing chambers have been designed without any “dead zones”. All seams are fully welded. As a result, no residual amounts of material can build up and contamination of subsequent batches is therefore eliminated.

The Ultrablend 95 is especially suitable for precise dosing of extremely small amounts of material directly into the injection moulding, extrusion or blow moulding machine. A maximum of four raw material components can be dosed by weight, one after the other, precisely as required by the recipe. They are then mixed together homogeneously in the downstream mixing chamber (4.5 litres volume) and fed into the feed throat of the processing machine. The minimum dosing amount is 3 g per component (900 g lot size). When two components are used a maximum throughput of 260 kg/h can be achieved. This gravimetric batch dosing and mixing unit is ideal for applications with frequent material changes: all parts in contact with the product can be rapidly removed and cleaned. In addition, the dosing slider remains closed during material changeover – not even the smallest amount of residual material can run out or be shaken out. The single load cell principle compensates for any vibration from the processing machine. This ensures the highest weighing precision.