The merger between Krauss-Maffei Reaction Technology and Elastogran Machinery will only strengthen the continual growth of the polyurethane industry. Each company’s machines will continue to be manufactured, with the merger increasing the annual output and allowing high flexibility for customers.
Plastics Machinery & Equipment will be the sole representative for both Australia and New Zealand, offering sales and service on both Krauss-Maffei and Elastogran machines.
The company says that over the past few years there has been a large resurgence in the polyurethane industry, thanks primarily to the automotive industry. The Ford Barra has returned to using a PU back-filled instrument panel. This enables a vastly improved product, and is manufactured by Venture Industries. Another leader of innovation is
Schefenacker Vision Systems, which is back-filling door mirrors with rigid PU.
Both companies approached Plastics Machinery & Equipment to supply the full turnkey machinery, covering both the metering unit and the mould carriers/carousel. Manufacturing and integration of the wet end to the dry end was done successfully in Adelaide.
Other leading manufacturers in the PU industry are Air International with carpet and seating lines and UP Tooling, which manufactures the complete body kits for GM Holden’s HSV Monaro and Mitsubishi’s VRX Magna.
Other applications for PU are in the building, refrigeration, water heating, leisure, furniture and medical industries.
According to Plastics Machinery & Equipment, polyurethane’s resurgence is due in no small way to recent technology developments in long fibre injection (LFI-PUR) and clear coat moulding (CCM).
Long fibre injection molds of polyurethane (LFI-PUR)
LFI-PUR represents a significant innovation in S-RIM technology. The process, for producing glass fibre reinforced polyurethane parts, brings product performance and manufacturing cost and flexibility benefits, particularly in large area parts.
Advantages derive from the innovative processing unit which delivers a microprocessor controlled mix of chopped glass fibre and polyurethane to an open mould.
The quantity (up to 50 per cent content) and length (12.5-100mm) of glass fibre, and the volume of polyurethane in which they are mixed, are varied as they are poured by the handling robot into the mould in order to meet the precise performance requirements of the part.This provides reinforcement exactly where it is needed and reduces wall thickness and weight.
Manufacturing benefits
Krauss-Maffei sees LFI-PUR eliminating many of the quality and cost drawbacks
associated with more expensive glass mats and preforms used in the S-RIM process.
Discharging a glass fibre and polyurethane mix directly into a mould (most existing S-
RIM moulds can be used for LFI-PUR) means fewer manufacturing steps with no
production, handling and loading of glass mats or preforms, and with the integration of
different functions by using in-mould films, fabrics and coatings.
Other benefits are the avoidance of material wastage (no loss of glass mat and preform
through trimming), higher levels of repeatability through isotropic arrangement and
intensive wetting of glass fibres, and a more environmentally friendly process with
reduced waste and no work associated hygiene problems handling glass fibre roving
compared to glass mat.
Production system
LFI-PUR installations are flexible and can be based on either a linear, equipped with
shuttle-type mould carriers, or rotary geometry (tables with up to 8 stations). Specification
depends on output requirements in terms of both volume and flexibility.
Product performance
In terms of product performance LFI-PUR means meeting large-area part specifications
with thinner wall sections and lighter weight, better dimensional stability and more
accurate fit(reduced shrinkage), and greater part to part consistency.
It has been the medium volume automotive and truck sectors that have taken most
advantage of the technology. Current application examples are the dashboard carrier on
the BMW 5 and 7 series and the Renault Espace, side door panels on the Mercedes
CLK… which integrates LFI-PUR and a fabric trimming, and the roof module of the MCC
Smart car, which integrates a PMMA/ASA film laminate, LFI-PUR and a fabric material for
interior trim.
The technology is beginning to realise external body panel applications, requiring high
quality finishes, and this is a major focus for Krauss-Maffei’s Munich R&D; resource. Class
A finishes can be achieved by post-painting as with many other processes, but in-mould
coating (IMC) is catching up.
With IMC, a single component paint is sprayed into the mould cavity and flashed off
before the glass fibre and polyurethane mixture is discharged onto the coating via an
oscillating unit. In the US, Romeo Rim is using IMC to produce truck sleeping
compartment panels.
The future
According to Jason Nagel of Plastics Machinery & Equipment, the future for LFI-PUR is a
very positive one. With automotive companies continuing to segment the market place,
more and more niche vehicles with production runs suited to the process are being
designed.
In addition, lower volume industrial vehicles ranging from earthmovers to tractors are
increasing the specifications of both interior and exterior components, in terms of both
performance and appearance.
Clear Coat Moulding (CCM)Decorative automotive mouldings for interior and
exterior applications, trays and Petri-dishes for medical applications, as well as furniture
components and design elements, all require non-fading and scratch-resistant surface
sealing.
Coating with crystal-clear or coloured polyurethane offers a high quality, but cost-
effective alternative to conventional methods.
In the conventional way, components in wood, aluminium or carbon fibre receive
elaborate preparative treatment before being coated with unsaturated polyester varnish.
Up to ten coats are applied in order to achieve the specified thickness of varnish at the
respective surface quality.
Each varnishing process is followed by intermediate gelling, which takes up to 20
minutes at room temperature. The completed polyester coat requires a curing-time of
between 48 and 72 hours. The top layer of varnish is then surface-ground.
In order to obtain uniform layer-thickness on radii, a thicker coat is applied to start with,
which must then be planed to a mean radial thickness by grinding. All clear-varnished
surfaces become opaque through grinding and can only be returned to their pristine
state by a labour-intensive polishing process. This laborious treatment takes several
days, under strict emission control, and is very costly.
High value enhancement
CCM, a relatively new process for surface-coating mouldings with polyurethane, has
numerous advantages. Alipathic polyurethane is non-fading, has excellent bonding
qualities with wood, metal and various textiles. It is also available in rigid as well as
flexible formulation.
The effective rationalisation achievable at respective lot-sizes must surely be CCM’s
greatest advantage, because the coating process is performed in just a single operation.
The articles to be coated are inserted in a mould, whose cavity allows for the thickness of
coating to be applied, i.e. when the used mould is closed, there is a gap between article
and mould wall. In one operation, this gap is filled at high pressure with a two-component
polyurethane.
Due to the highly developed Krauss-Maffei mixing and metering technology, as well as
the mixing head repeatability, precision and bubble-free operation, the coating process
is completed after a few minutes’ reaction time, required by the polyurethane coating.
The article can then be removed from the mould. The surface quality represents an
image of the mould wall’s surface, so that the d�cor parts do not require any finishing.
Process benefits
This latest PU application replaces elaborate varnishing processes and is eco-friendly,
because it does not produce varnish waste or release volatiles inside the vehicle. The
varnish thickness is uniform across the whole of the moulding, and the tendency for
component warping is minimal.