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Visualization and control of the process of sheet moulding compound production at the Dutch company VDL Wientjes Emmen

May 26, 2014 | Bretislav Valek

VDL Wientjes Emmen is part of the VDL Group (VDL Groep). The VDL Group is
an international industrial company focused on the development, production, and sale of semi-finished products, buses, and other finished products, and the assembly of cars. It is a collection of flexible, independent companies, each with its own specialty.


Since its establishment in 1953, this family business has grown into a multinational corporation with 84 companies, spread across 19 countries and with nearly 9,500 employees. Since 2005, VDL Wientjes Emmen has been part of this group.


VDL Wientjes Emmen is a versatile producer of both thermoset and thermoplastic products, no matter whether it is in large or medium series. The company's strength lies in applying the latest developments in the field of raw materials and processing, combining various production techniques and the assembly of products, which allows for creating both simple and highly complex plastic components.


The Reliance 4 SCADA/HMI system is used by VDL Wientjes Emmen in the production of Sheet Moulding Compound (SMC). It is a thermoset, fiberglass-reinforced plastic semi-finished product. VDL Wientjes Emmen produces SMC for use in its own press shop and for third parties. They have a variety of application-specific recipes developed in their laboratory, using many years of expertise. Objects made of SMC include mailboxes and trash cans.


Because of very high chemical resistance, strength, and temperature resistance, SMC is particularly suitable for products with high demands. Its aging characteristics are so good that, even after many years of outdoor use and exposed to high UV radiation, the mechanical characteristics of SMC hardly reduce. SMC products are maintenance-free and resistant to impact, scratch, fade, temperature, and corrosion. With the addition of special additives, a high degree of fire resistance and low flue gas emissions can be achieved.



Control system

The manufacturing of SMC is divided into two separate systems, line 1 and line 2.


Line 1 is the beginning of the process. Polyester resin is pumped into a mixer with a capacity of 5,000 liters. Here, a number of other raw materials are added and mixed. These may be liquids as well as powders. Recipes in Reliance contain the required quantities that are loaded into the Hitachi PLC, which performs the process.


VDL Wientjes has made several dozen recipes in the Reliance system for all their products. Reliance also shows the different stages of the process.


Line 2 is the making of SMC. SMC is a polyester mat made of resins, glass fibers, pigments, fillers, and additives. The process begins with pumping the resin mixture (made in line 1) from
a storage tank. This resin mixture is called slurry. The slurry is pumped through a flow tube and then mixed with a certain percentage of color and magnesium oxide (MgO). The amount of added MgO is trended and displayed on a screen.


The slurry is then spread on foil and the glass fibers are added (they may vary in length and quantity, depending on the desired properties and geometry of the product). After that, a second layer of slurry is added and covered with foil. Lastly, the entire mat is impregnated. Before SMC can be processed, it is ripened under controlled conditions.


The Reliance SCADA system makes it possible to fully visualize all valves, motors, temperatures, density, etc.



Examples of visualization windows



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