Krallmann AG presented the latest development of the particle foam composite injection molding (PCIM) process in March 2014. Brexeler, Krallmann’s technical managing director, told that Krallmann intended to call the application “K-Fix” (standing for Krallmann-Fix). This was officially confirmed in September when Krallmann announced K-Fix as a new product line.
The K-Fix parts will be shown by injection moulding machine producer Arburg, which will produce them in a cell involving particle foam moulding and injection moulding of the core fittings, with part removal and transfer of foam mouldings and the complete K-Fix parts by a six-axis articulated robot. PCIM process opens up new applications, particularly in lightweight construction and in thermal insulation. Secure assembly of large parts such as car bumpers are conceivable. Krallmann says this latest version of the PCIM process is by no means limited to standard K‑Fix threaded fitting elements, but that it may be used for particle foam parts with clips and snap-fitting elements, and also for various tailor-made customer solutions. All versions feature integrated parts with inherent tight sealing against ingress of dust and liquids.
Brexeler sees potential for insulated door panels made in a single-stage process and applied to electric vehicles, reducing heating and cooling demands on battery capacity. Krallmann’s work in this area is assisted by its membership of NILS, a German network for intelligent lightweight construction systems. As with the first PCIM parts, a defined degree of melting of the particle foam surface ensures tight bonding between the particle foam and the moulded-in plastic part, “making the two components inseparable”. Krallmann says the contrasts with purely mechanical insertion of components in particle foam, which are held less tightly, due to voids between individual ball‑shaped foam particles. PCIM’s tight bonding approach also applies when the integrated foam/fitting part is in turn overmoulded by particle foam in a subsequent process, involving here foam-to-foam bonding.
Source: Krallmann AG
Prior to K-Fix development, Krallmann showed PCIM process involved a model aeroplane wheel developed with particle foam producer Ruch Novaplast in Germany, by moulding a PP wheel rim into a 5.7cm diameter particle foam “tyre”. The development partners subsequently developed the process further, overmoulding the wheel with a third component – a Thermolast K TF 7 ATL grade of thermoplastic elastomer from Kraiburg TPE. This was first demonstrated at Arburg’s March 2013 technology days open house, the complete 13g 3-component wheel rim being moulded into the foam and overmoulded on an Arburg A370 S injection moulding machine with 60s cycle time, as part of a production cell with a single-cavity Krallmann mould and including automatic packing in plastic bags. Engineering consultancy Kiki Ingenieursgesellschaft and packing system specialist AVT Automotisierte Verpackungs Technologie supported the project. LyondellBasell had supplied its Metocene HM 1753 grade of metallocene PP for the PP rim. While the first production cell used an Arburg Multilift handling robot, by the March 2014 Arburg open house, a 6-axis articulated robot was used, with cycle time cut to 40s.
Krallmann has been involved from the outset in the integrated metal-plastics injection moulding (IMPIM) process developed at IKV. The first IMPIM process examples were sport sunglasses with electrical demisting, moulded by IKV on a Ferromatik injection moulding machine. Krallmann developed and supplied a 3-station index plate mould. This is used in moulding the sunglass frame around contact pins, the plastic lenses, as well as low melting point (200°C) tin-zinc alloy metal conductive heating tracks onto the lenses. Other project partners were Kistler for mould sensors, Hasco for mould components, while GWK (Gesellschaft Wärme Kältetechnik) developed the rapid heating and cooling system with ceramic heaters. The automation system used ASS handling equipment and a Kuka multi-axial articulated arm robot. At Fakuma 2012, however, it was KraussMaffei Technologies that demonstrated IMPIM with integrated low melting conductive metal tracks moulded onto a transparent Bayer MaterialScience polycarbonate battery-driven LED table lamp structure. This was then overmoulded to encapsulate the tracks with transparent blue polycarbonate as the third component after LED insertion. KM moulded the lamp with a CX 160 380/55 IR600 machine with 82s cycle time for the 39g part, of which 30g and 7g for PC components and 2g for the metal tracks.
CX 80 hybrid drive machine’s generous space for tooling easily accommodates the Krallmann metal injection unit. Its LRX 50 linear robot removes the finished parts from the mould and is protected by the moulding machine’s standard protective barrier. Aside from PCIM and IMPIM integrated production processes, Krallmann has also been involved with the use of the microcellular physical foam process from Trexel on a Styrolution ASA/PC copolymer washing machine cover.