In previous articles, AT Engineering specialists described how change parts such as augers and dosing pumps work. Today we look at star wheels (turnstile stars).
In food and pharmaceutical production, rotary machines are widely used for filling liquid and viscous products into individual containers and bulk products into bags and tubes, for marking and labelling containers, and for tableting bulk products.
Empty bottles are fed into the process rotor at the filling station, and filled bottles are discharged from it, by slotted transfer rotors. The working elements of these rotors that actually transfer the bottles are discs with shaped pockets around the circumference that follow the cross-section of the bottle. That is why in practice slotted transfer rotors are often called star wheels.
Modern production lines can combine several process rotors, for example rinsing, filling and capping. Depending on how many process rotors are combined, such units are called monoblocks or triblocks.
For example, one monoblock layout (for filling and capping) consists of 2 process rotors and 3 transfer rotors (guide stars), while a triblock layout (for rinsing, filling and capping) consists of 3 process rotors and 5 transfer rotors (star wheels). Many other variants are possible.
Star wheels are made from exceptionally durable materials:
- first of all, AISI 314 and AISI 316 steels, which need no introduction;
- caprolon (polyamide) — an excellent substitute for non-ferrous metals and their alloys; resistant to hydrocarbons, oils, alcohols, ketones, ethers, alkalis, formic and acetic acids; it does not decompose or release harmful substances during machining, which is very important in pharmaceutical production;
- ERTACETAL C — suitable for long-term use at temperatures up to +100 °C; thanks to its high hardness it has good sliding and wear properties; resistant to hydrolysis and chemicals; absorbs little water; machines very well and is dimensionally stable;
- PTFE (fluoroplastic) — an excellent material with a low coefficient of friction, outstanding chemical inertness and water-repellent properties; operating range from −269 °C to +260 °C; physiologically and biologically harmless; melting point about +327 °C; can be turned, drilled, milled and ground.
AT Engineering specialists will select the right material for infeed and outfeed star wheels based on your specific operating conditions and wear-resistance requirements.
