LOMOLD™ – Integrating the benefits of traditional processes
Unlike other processes, the Lomold™ Technology has been developed specifically to allow moulders to capture the benefits of injection moulding and compression moulding without having to compromise in any way. Imagine being able to design parts in 3D (like injection moulding) while keeping the material properties of long-fibre composites (like compression moulding) and you have a good idea of what the Lomold™ Technology enables you to do.
Throw in the ease of operation, quick cycle times, ability to mould hygroscopic materials such as nylon in a closed process, reduction of weld lines, low warpage, large shot sizes and the capability to mould against soft skins – all of this in one process step (finished part in the mould) – and you have a comprehensive solution that is revolutionizing the long-fibre industry.
To find out more, please see the technology site here.
The most important feature of the Lomold Technology is its ability to keep fibres long into the final part. The critical glass-fibre length in PP is 10mm – Lomold produces large parts that have been moulded with average fibre lengths in excess of 15mm, after flowing for more than 1.2 metres through a series of rib structures only 2mm wide. Previously, such fibre lengths have only been possible with compression moulding – which limits the design possibilities.
In parallel with the ability to keep fibres long, the Lomold Technology allows parts to be designed and moulded in 3D, exactly like with injection moulding.
The combination of the 3D design and long fibre results in superior parts that have unsurpassed mechanical properties, while complex rib structures and weight reduction in non-critical areas allow lightweighting and subsequent part cost reductions.
Lomold 3-D-LFT machines are simple to operate as they are built on the same platform as traditional injection moulding machines – up to 90% of a Lomold machine is standard equipment. The major difference is in the way Lomold injects material into the mould – and this patented process has been tried and tested in several machines and operating environments. The user interfaces have been customized to allow moulders to set Lomold-specific parameters.
The Lomold Technology is a closed process from start to finish, meaning that material is never exposed to air. This allows materials such as nylon to be moulded with perfect surface finishes while keeping fibres longer than 8mm. Previously, compression moulding such materials would affect material properties and surface finish as a result of the exposure to air and subsequent oxidization, while injection moulding would produce very short fibres in the part.
The patented Lomold Technology replaces a conventional mould’s hot runner injection system with a piston moulding system whereby the piston face becomes part of the bounding wall of the mould, essentially “closing” the mould at the end of its stroke. This system keeps fibre-lengths intact as the material is injected gently with very low shear – while allowing quick cycle times, as there is no sprue that needs to be cooled.
Injection moulded parts’ cycle times are often determined by the size of the sprue, as it can be the thickest section of a part. As Lomold has no sprue, cycle times can be considerably faster. Long glass is able to conduct heat from the molten polymer more efficiently than short glass – this effect is enhanced as glass fibre loadings are increased. Another factor that plays a large part in injection moulding is the filling time – this determines the temperatures at which moulds can be run and influences cycle times with less shear than conventional injection moulding. Lomold’s filling time is up to 60% quicker, allowing lower mould temperatures and subsequent cycle time reductions. While packing of the part takes place, Lomold is able to recharge for the next shot, meaning that there is no lag between ejection and preparation for the next shot.
The much lower peak injection pressures and the shear lead to low stresses built into products, meaning that LOMOLD parts exhibit very little to no warpage over time, even in flat products.
In addition, the cooling profile is similar across the entire product (reduced temperature gradients) as a result of the quick filling times.
The LOMOLD™ Technology allows the final part to be produced in the mould, without the need for added cutting, trimming and stamping steps as commonly found in the compression moulding industry.
In order to fill large moulds, injection moulding uses multiple injection points. Due to LOMOLD’s large injection point, the number of weldlines are greatly reduced – providing significant benefits, especially with long-fibre materials that typically have reduced properties at the weldlines.
LOMOLD’s greatly reduced peak injection pressure, low shear and the entry through a large gate allows the moulding of filled and unfilled polymers against a soft skin, such as foam or a paint skin without tearing it.