Innovative Plastics technologies from KraussMaffei
KraussMaffei not only has the know-how to engineer advanced systems for the three major plastics processing technologies - injection moulding, extrusion and reaction moulding. The company also develops innovative processes that open up totally new applications for plastic components.
Plastics are extremely versatile materials and the number of applications in which they are used has been growing steadily for decades. Two factors are driving this development. Firstly, plastics compare very favourably with conventional materials, like metals, because of the greater degrees of freedom for specifying material characteristics. Secondly, plastics offer huge potential for optimizing manufacturing costs. Multi component technology is a striking example. Multi component processes are sometimes very complex, on the other hand, the potential for savings is amazing. Savings come mostly through reducing component count, which in turn reduces manufacturing and assembly costs.
There are different methods of shaping several different types of plastic melt in one mould to an integrated component. These include composite, multicolour, sandwich and assembly moulding.
For Dr. Erwin Bürkle, Director of Pre- Development New Technologies/ Process Engineering in KraussMaffei`s Injection Moulding Machinery division, has this important comment to make. - It takes the right combination of machine, mould and process to provide the necessary framework for cost-competitive production - he says.
The machine itself is by no means the only factor that has to change in order to drive development of advanced plastics technologies. Jochen Mitzler, head of Product and Technology Management in KraussMaffei`s Injection Moulding Machinery division says: - Innovative plastics need smart machine engineering. And here`s where KraussMaffei is a competent development partner.
His statement is backed up by trailblazing technologies that successfully combine different processes. Take SkinForm, for example, where an injection moulded substrate is overmoulded with a PUR cast skin. It`s a one-step process capable of producing diverse, high-value surfaces, for example, automotive cockpit components.
X-Form is one of the newest variants of multicomponent moulding. Combining three technologies - injection moulding, extrusion and reaction processing - X-Form opens up a completely new range of applications for plastics.
It was developed by KraussMaffei in a collaboration with Elastogran GmbH and Mues Products & Moulds GmbH. X-Form has been designed for applications which currently use metal-rubber composites. Possible applications include covers for housings with integrated seals or engine mountings. The process uses a new thermoplastic polyurethane (TPU) called Elastollan, made by Elastogran, that crosslinks to TPU-X during cooling. Crosslinking takes place in an injection moulding compounder where the crosslinking agent is mixed evenly with the TPU melt. The mix is then supplied, via a shot-pot, to the discontinuous injection process.
As a practical illustration of the process, KraussMaffei and its partners designed a roll restrictor, a component used in machine mountings or in the running gear of a car or truck.
At the K2007, the company demonstrated an injection moulding compounder cell producing this multicomponent part. The roll restrictor is made of two materials: the body and collar are made of Ultramid CR, a glassfibre-reinforced plastic from BASF. Between the body and the collar is a damping element made of TPU-X. An elastic seal around the component is also made of TPU-X.
The most strikingly innovative aspect of the production process is the cycle time; a finished part is produced every 60 seconds. This is achieved by producing each part in three work phases that take place simultaneously in the manufacturing cell. The fourth phase is demoulding by a linear robot. The damping element in the roll restrictor has a wall thickness of 15 mm to be capable of absorbing strong vibrations. Material this thick would normally need a longer cooling time and therefore a longer cycle time. Using a turntable mould and a smart process, the cooling time can be kept to a minimum. The body and the collar are first injection moulded from polyamide. The mould turns 90 degrees and TPU-X is injected between collar and body in a star shape.
Another 90-degree turn and the gaps are filled with more TPU-X. Finally, in the fourth phase, the part is removed while the mould is closed. Compared with conventional elastomer processing, cycle time here is reduced by a factor of four to six.
Nonetheless X-Form is in many respects a conventional 2C thermoplastic injection moulding process. The mould need not be designed with the hot and cold zones, normally required when working with rubber/thermoplastic composites. This makes process control far easier.