Pre-treated Plastic Pins

Plastic Pins with Plasma Pre-Treatment in Gas Built-in Cookers Openair-Plasma enables safe and durable bonding of plastic and glass without the need for primers or other chemicals. In this article, we will explain the details of this technology and its advantages through an example project. Bonding plastic and glass to each other is quite difficult. Nevertheless, if these two materials are to be joined, the surface must definitely be prepared beforehand. The Openair plasma technology offered by Plasmatreat enables efficient, economical in-line processes and provides significant advantages over wet chemical methods. Turkish appliance manufacturer Mamur Teknoloji Sistemleri also began using plasma instead of primer a year ago and is satisfied with the results in every respect. The company, headquartered in Istanbul Silivri, succeeded in increasing the adhesion strength of plastic-glass connections, optimizing its processes and increasing efficiency; and at the same time reduced its costs. Cooking with gas has many advantages: heat becomes ready for use quickly and distributes evenly, reaction times are short and it operates very economically. Professional chefs especially trust gas cookers, but increasingly more amateur cooks are also discovering this proven old technology. Cooking and frying over an open flame is popular. Sufficient distance between the burner and cooking vessel is ensured, with cooktop grates for placing pans and pots. These grates are usually removable, yet still need to be sturdy and balanced.

Surface activation before bonding plastics is indispensable

In the products of Turkish manufacturer Mamur Teknoloji Sistemleri, the cooktop grates are therefore placed on plastic pins fixed to the stove's tempered glass panel. These pins must withstand impact forces of up to 20 kg, as stresses are inevitable during placement of cookware, movement of cooktop grates and cleaning of the stove. The pins are made from polyphenylene sulfide (PPS) semi-crystalline high-performance plastic. This thermoplastic indeed has very high heat resistance and strength and is therefore very suitable for kitchen use; however, due to its non-polar surface, it poses difficulties for adhesive processes. Barış Öz from Mamur Teknoloji states, "Plastics have good mechanical properties, but are difficult to bond due to their low surface energy. Therefore, plastic surfaces must definitely be pre-treated to ensure that the adhesive bond has the best strength and durability. This pre-treatment is one of the most important steps in the adhesive process." When the surface to be wetted has excessively low surface energy, the adhesive cannot spread homogeneously on the bonding surface. Insufficient spreading resulted in inadequate adhesion and, as a consequence, pin fracture under mechanical stress. This is a safety risk that must be prevented.

Atmospheric pressure plasma: An alternative to wet chemical methods

Until a year ago, Mamur Teknoloji used chemical substances called primers for pre-treatment. However, this appliance manufacturer, which exports its products to 46 countries, was not satisfied with this classical method. They believed this method was too costly, not sufficiently flexible and not environmentally friendly. For this reason, Barış Öz and the Mamur team began searching for an alternative. They found what they were looking for at Plasmatreat, experts in atmospheric pressure plasma processing. The company, headquartered in Steinhagen (North Rhine-Westphalia), has been developing innovative solutions for surface modification using its own plasma technology for nearly 25 years. They were immediately convinced: Openair-Plasma was exactly the solution Mamur Teknoloji was looking for. Öz explains, "Pre-treating non-polar polymers with atmospheric pressure plasma greatly increases surface energy. This allows the pin surface to be wetted better and also increases the strength of the bond between the plastic pin, adhesive and tempered glass panel. No deformation occurs and high product quality is ensured." He adds, "The ease of use, cost efficiency, process safety and environmental friendliness also convinced us."

Openair-plasma enables efficient, economical in-line processes

The way Openair-Plasma works is both simple and effective: The static electricity discharge effect of the plasma beam neutralizes dust particles freely resting on the surface and removes them from the workpiece surface. The plasma also activates the plastic surface to be treated by incorporating functional groups containing oxygen and nitrogen that increase the polar portion of surface energy. Thanks to the high energy level of plasma, the structure of organic and other chemical substances on the material surface can be specifically modified. This allows the entire surface in the treated area to be wetted homogeneously with adhesives or paints, thereby creating a durable bond. The appropriately operating plasma beam can follow the workpiece geometry with millimeter precision. It is integrated into the production process in-line, meaning no cell systems are needed. The product remains on the production line and can continue to be processed directly after the plasma treatment. This makes production processes simpler, faster and much more cost-effective.

Adhesion strength and long-term durability increased significantly

At Mamur Teknoloji, the number and position of pins vary depending on the cooker model and size. For this reason, Plasmatreat technology works together with a cooperating robot. This provides maximum flexibility and allows different device models to be produced on the same manufacturing line. The plasma treatment is performed with an effective beam width of 10 mm and a speed of 20 mm per second. Barış Öz expresses his satisfaction, saying, "Thanks to the high processing speed and integration into the production process, surface treatment performed with plasma is handled much faster than with primer. This allowed us to significantly increase our efficiency compared to before." Additional work steps, as with primer use, are no longer necessary. The adhesion quality satisfies us in every respect. The surfaces to be bonded hold together much better. For example, tests showed that the adhesion strength of plastic-glass bonds made with plasma technology is 1.6 times higher than after primer treatment" he says enthusiastically. The long-term strength of the adhesive bond was also improved; this positively affects the service life of gas cookers.

Plasma use proved successful, application areas to be expanded

Mamur Teknoloji has not regretted switching from primer use to plasma for even a moment. On the contrary: Plasma technology proved itself so well that its use in other areas of manufacturing is being planned. For example, it is currently being tested whether it can be implemented for pre-treatment of steel and sheet metal. Öz emphasizes, "Compared to conventional pre-treatment methods, plasma offers many advantages such as high quality surface treatment, easy and fast application, cost-effective production and process safety." "Plasma is clearly ahead in terms of environmental friendliness. Thanks to it, we don't have to use dangerous and environmentally harmful chemicals—it's a clean technology. It also provides benefits in terms of occupational safety." Speaking of safety: Thanks to Openair plasma technology, plastic pins are firmly bonded to the tempered glass surface, offering high resistance to impacts and vibrations even when the cooker is used somewhat roughly. In conclusion, cooking enthusiasts can swing their ladles without any concerns and fully enjoy their passion. Enjoy your meal! Hakan Sağkal General Manager Plasmatreat GmbH Turkey Liaison Office