MANN+HUMMEL ProTec: Technoform carries out trials on profile extrusion tools with flexible material handling

Tool expert Technoform Extrusion Tooling imposes a wide range of requirements on material handling for trials on profile extrusion tools: Four extrusion lines are to be fed with varying mixtures of materials to be dried.

MANN+HUMMEL ProTec designed and realised a versatile complete material processing system for Technoform Extrusion Tooling (TET), a company of the world-wide operating Technoform Group at the TET location Kassel-Lohfelden. The system comprises two SOMOS® D400 dry-air dryers and nine drying hoppers with a drying capacity of a total of 3,000 litres, a SOMOS® Gramix Compact 400 gravimetric dosing and mixing system as well as a central conveyor system including octabin and extruder feeding device. The controller software is tailored to the TET requirements and provides great flexibility for feeding the four extruders - parallel with several standard dried material mixtures as well as individual formulae with direct dosing and mixing of up to five dried materials during operation.

Technoform Extrusion Tooling designs and manufactures high-precision tools for the extrusion of plastic profiles exclusively for the companies of the Technoform Group. The international production locations of the Technoform Bautec Kunststoffprodukte GmbH specialising in the production of plastic insulating profiles for the construction industry are the contractors of the Kassel-Lohfelden location (the TET headquarters are located in Fuldabrück near Kassel). Thermal separation with Technoform profiles provides for the high thermal insulating properties required of modern aluminium windows and facades, combining various designs with aluminium profiles or casings.

Normally, a glass-fibre reinforced PA 66 type is used for the manufacture of profiles for reasons of stability, stiffness and thermal resistance, but it is not used as a sole material. Mixtures of up to five materials in different compositions are currently often used to meet the requirements on profiles manufactured with a precision of ± 0.05 mm and a weight of seven to 2,000 g per metre. All material mixtures must be dried before being processed. When carrying out tool trials up to verification of the suitability for series production TET simultaneously defines the extrusion parameters for series production at the international Bautec production locations in Europe (Italy and Spain), the USA and Asia (China and Japan).

Versatility and flexibility have top priority
If a fixed material formula for a profile already exists at the start, the newly constructed tools are commissioned with these so-called standard material mixtures. Three drying hoppers, one with 1,200 l and two with 300 l capacity supplied with dry air via a D400 dryer are available for drying. The SOMOS® Gramix Compact 400 batch dosing system which is part of the overall conveyor system prepares the mixtures directly from the materials provided in the octabins in accordance with the formula specifications. For this, two main components are precisely dosed with slides and up to three auxiliary components with screws. Subsequently, they are homogeneously mixed in a downstream mixing chamber and conveyed to the corresponding drying hoppers.

However, the extruders in the TET labs often process individual mixture ratios deviating from the customary standard formulae. It is not uncommon for a formula to be varied during a running test in order to optimise the mix composition. The aim is to achieve optimum profile properties (mechanical and thermal characteristic values) for the respective applications. The material mixture for this is again produced by the Gramix Compact batch dosing system, this time, however, from components which are already dry. The second drying system comprising a modular hopper system with six drying hoppers, three with 100 l and one with 200, 300 and 400 l capacity, respectively, supplied with air by the second D400 dry-air dryer provides for drying.

The central suction conveyor system is equipped with efficient conveyors from the SOMOS® FG200 series on the individual drying hoppers, the batch dosing material containers and extruder material hoppers. Undried materials are dried with normal ambient air whereas dried material flows are exclusively conveyed with dry air.

The special controller software based on a Siemens S7 displays all processes and functions on a 10” touch screen. This way, the wide range of tasks such as controlling, adjusting and storing mixture formulae for process documentation at the touch of a button occurring in the TET labs when commissioning extrusion tools can be handled comfortably.

More Information: www.mh-protec.com, www.technoform.com