During Rosti’s 75-year history, technical innovation and process enhancements have brought about great advances in plastic injection moulding. The first injection-moulded product – a billiard ball made in the USA – replaced ivory, a costly and unethical material. Today, precision-injected moulded parts are used as heart valves and joint replacements in surgical procedures. To ensure continuing innovation and maintain its position as the go-to contract manufacturer, Rosti invests heavily not only in new technologies to assist its customers, but also in internal innovation facilities – developing staff expertise and new equipment to support customers’ cutting-edge products.
The impetus to invest in the industry’s technical megatrend – LSR – was driven by a customer who needed a clearly differentiated product. The right LSR solution was developed with great care, as the product was to touch sensitive parts of the skin.
Due to various physical characteristics, including excellent compression set and elastic properties, wide temperature resistance (from -110 to +300°C) and high clarity, which enables bright colouring, LSR is a rapidly growing material in many markets. Furthermore, LSR is a highly inert material with several medical approvals. All told, this makes LSR highly suitable for both single-use and reusable applications.
Multi-shot moulding is a process in which different materials or colours are delivered into a cavity to produce a part in a single step. When using two materials it is known as 2k, using three materials is 3k, and so on. Multi-shot moulding reduces the need for additional tools and production steps, and results in an optimised, cost-effective manufacturing process. When a soft seal is required on a harder plastic – e.g. a toothbrush with a soft grip and hard body – multi-shot moulding is a very suitable technology.
Overmoulding is a process in which a component is inserted into the cavity of a tool and then moulded onto the component. This is often used in applications requiring metal contacts or studs when forming part of a plastic housing in many technical products. Due to the significant advantage of removing the additional assembly step and thereby reducing costs and improving the repeatability of the product, the overmoulding process is increasingly required by Rosti’s customers for electronic circuit production.
As the technology in electronic circuits improves, the option of manufacturing a product in different shapes, enabled by the flexible electronic circuit structure, allows designers far more flexibility in the design of products.
Different applications are available to add labelling or decoration to a part. In general, requirements differ from industry to industry.
In-mould labelling (IML) is often used in the food industry for products such as yoghurt pots, where the shelf life of a product is often measured in weeks or months rather than years. In this process, a pre-printed thin walled foil is added into a mould tool prior to the injection cycle. The foil attaches to the tool due to electrostatic charge or with a vacuum system, and forms part of the product after the injection process.
In-mould decoration (IMD) follows the same process but utilises a thicker foil and is therefore used in applications that require a product life measured in years. It is a more expensive process than IML, but offers a robust long-life label or decoration. The process is used, for example, in the labelling and branding on power tools.
Compared with painting a product, which involves an additional process, in-mould labelling and in-mould decoration both offer a cost-effective, repeatable process.
Rosti also offers digital printing. This is the real-time process of printing labels or decoration onto parts after they are produced in a moulding machine. The main advantage of the digital printing process is high-speed printing with a quick changeover of the printing design. For example, high-volume parts (often from a high cavity tool) can be printed in batches to suit different markets.
As a contract manufacturer, Rosti’s philosophy is to drive innovation and technology to meet customers’ needs and create value for both parties. With 3,500 employees, over 4,000 customer tools run from more than 400 injection moulding machines across eight locations worldwide, Rosti is big enough to cope when it comes to large, complex projects, yet small enough to care about services that are important for a specific customer. With 75 years of experience, Rosti has developed a highly efficient supply chain and acquired the logistic expertise to ensure that the lowest cost and highest quality are delivered to its customers.
Rosti supports customers in developing brand new products, as well as improving the performance of existing products, so-called value engineering, to provide a result that is as competitive as possible.
There are many reasons why value engineering is implemented for an injection moulded product or part. The product might be obsolete or need improved functionalities. There may be a need to change the material, or bring in new or improved technologies, or optimise or reduce existing components. Rosti’s engineers are always happy to work with customers to identify improvements following a tried and tested process.
Rosti innovation centres key result areas
Simply described, plastic injection moulding is a process of melting plastic pellets and injecting it into a mould or cavity to form a shape. Once the shape is formed, the material is cooled, ejected from the machine and – voilà – a finished, functional, esthetically pleasing injection moulded product or part is ready!