Those who have a car with quality interior finishing, in which even humble parts such as the air conditioning control guard or the electric window buttons, are considered in even the finest detail, are probably using products that have been manufactured at the Progind factory in Azeglio (near Turin, Italy). For the past forty years this company has been producing moulds and moulded parts on both a large and small scale, for the automotive industry above all. It is a difficult sector with a growing risk that that its clients decide to shift even the most banal of operations abroad, to countries in which labour costs and tax rates are lower. The only way of preventing this trend is that of taking up products with a high added value, incorporating high-tech solutions both in terms of mould design and construction as well as in terms of the actual moulding process. This is the strategy adopted by Progind, a company that has recently been focusing on IMD (in mould decoration) in particular. IMD is a well-known technique which makes it possible to insert a screen printed film into the mould in order to manufacture plastic items of high aesthetic quality in a highly efficient manner, which would otherwise be difficult to obtain using other moulding techniques. By using a screen printed film it is possible to start from any source with a high degree of colour depth, photograph or drawing, to manufacture an end product that is scratch and solvent resistant, and can also be backlit. This technique offers great potential for increasing the appeal of many products including car “dashboards”. An example being the recently produced control panel of a car air conditioner.
All in the mould
The tab that this Piedmont company has recently completed for a car air conditioner control, consists of a screen printed foil applied to two co-moulded polymers on an injection moulding machine. It is pleasing both to the eye and to the touch, in a shiny black colour, the tab leaves the press ready to use, thanks to a film on which the typical air conditioner icons have been screen printed, overlaid on the transparent insert next to which the back lightsource will be positioned.
Each screen printed icon coincides with mould cavities that are broken down into inserts, so that there is no contamination (light dispersion) between the switching on of one light and another. In this case it is a bi-injection process, although Progind is also equipped for tri-injection processes. The part (height of 70 millimetres and length of 235 millimetres) is injection moulded by means of a Arburg 520S press with rotary table, into the mould of which the dark and clear polymers are injected, covered with an Extraform screen printed foil by MacDarmid in a single cycle, the foil arrives at the Azeglio company already printed and cut. All with a cycle time of a mere 50 seconds, without having to make use of any external infrastructure or departments, which is often the case when quality finishing is required.
The mould that has been designed and made by Progind – and in which the company invested thousands of hours – has two cavities for use with a rotary table. In order to avoid problems such as part distortion or screen print washing, a special device for the intensive conditioning of the mould cavity and the platens has been used. Furthermore the mould movements are dry, thereby not requiring any lubricants. Injection is undertaken by means of a hot runner system with double manifold plate and direct injection points.
Not only automotive
The field of application of this technology is vast: from the control panel of an automatic coffee machine or of an aerosol to the control buttons of a fridge. That is, in all those situations in which the added value of a product is important, with the typical tri-injection features, as for example the possibility of producing a panel with parts moulded using different materials and in different colours or even transparent, with a surface finish that can be screen printed as required, all in a single stage. In this particular case, the screen printing involved the control of an air conditioner, but it could also involve the realistic reproduction of a briarwood finish or any kind of graphic material, from a drawing or a photograph.