MACHINERY | MIXERS
aspects. “Critical components were specifically optimised for this purpose,” he says. There are already various solutions on the market for automatic cleaning of the container and, since multiple containers can be used with a single mix head, this operation can be done offline without affecting productivity. But if a recipe change is required, Schluckebier says, the parts of the mixer that come into contact with the product have to be thoroughly cleaned. Contamination on the surround- ing periphery must be completely removed too. “In order to ease the cleaning of the mixing tool, the tool should be easy to dismantle and free of sharp edges and shadows. In addition, the pres- sure on the wall and bottom created during mixing should be kept to a minimum so that there are no deposits in the mixer and there is no high increase in the material temperature,” he says. Mixers are often equipped with slow-running
Right: Zeppelin’s new container mixer works with a wing-profile tool mounted on a flat, polished plate
tools that may work in combination with one or more high-speed dispersion tools. “In view of the cleaning aspect, the aim was to combine moving and dispersing in one tool,” says Schluckebier. “With the usual tools, the bottom clearance must be kept very small so that the material circulates evenly in the mixer in the form of a vortex. A large distance means that the material is no longer lifted sufficient- ly, resulting in an uneven distribution. Although a higher peripheral speed counteracts this, the result is a higher rise in tempera- ture and deposits on the tool and mixing head.” The answer to this quandary came with the development of a new tool with a wing-like cross-sec- tion. The mixing arm, which has “winglets” similar to those often used on commercial airplanes to
reduce air resistance, produces a very low mixing resistance. “This reduced energy input limits the temperature rise to less than 2°C/min,” claims Schluckebier. It also allows a higher tool speed (up to 20 m/s), which in turn increases dispersion. The high lift force created by the geometry of the wing allows a very large bottom clearance (up to 70mm), which facilitates cleaning between the tool and mixing head. In addition, the shape and the polished surface of the mixing tool prevent deposits and, on top of this, the mixing tool is light in weight (around 15 kg for a 1,000-litre mixer), so it can be dismantled very quickly for cleaning or replacement by another pre-cleaned tool. A further benefit of the high lift force is in the
seal area. Most mixing heads are trough-shaped, with a seal around the rim where deposits can accumulate. Schluckebier says that the high lifting forces on the CMQ make it possible to use a much easier-to-clean flat plate instead. “This combination achieves at least equivalent results compared to other container mixers equipped with homogenising and dispersing tools,” he says.
PHOTO: ZEPPELIN SYSTEMS
Plant cleanliness Container mixers are usually moved under the mixing head on a guide system in the floor. When the container is moved away at the end of the mixing process, some material almost always falls off the mixing head and mixing tool onto the rails. Schluckebier says the design of the CMQ container holder and clamping rotary holders makes it possible for the container to be centred with no need for rails, making floor cleaning much easier. Combined with the other system features, cleaning times can be cut down to no more than 15 minutes, he says, compared with anywhere from 40 minutes up to two hours.
Hot over cold Cleaning takes much longer
Left: The three-part design of Zeppelin’s new high-speed mixer is said to ensure easy and quick cleaning
60 COMPOUNDING WORLD | November 2019
with hot mixing than with cold mixing because the entire mixing container and the
lid must be cleaned and the multi-component tool set and deflector (where used) must be removed in order to gain access to all corners and edges. Zeppelin has been making changes here, too, resulting in what Schluckebier says are significantly reduced cleaning times. Removing the mixing tool from mixers with a fixed
www.compoundingworld.com
PHOTO: ZEPPELIN SYSTEMS
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86
