When the focus is on conveying and filter systems for chips and cooling lubricants in the metal machining sector, KNOLL Maschinenbau, Bad Saulgau, is an institution. Worldwide, numerous manufacturers of turning, milling, and grinding machines for cooling lubricant cleaning and supply rely on high-performance components from this Swabian company.
Whether in stand-alone or central systems – centrifugal pumps are the heart of cooling lubricant systems. KNOLL has developed and produced these pumps in-house in a variety of models and sizes for many years. Depending on the configuration and size, the pumps achieve delivery rates up to 1600 l/min, pressures up to 6 bar, and they are suitable for particle sizes up to 30 mm.
At EMO 2017 in Hannover, KNOLL (Hall 7, Booth C22) will present a newly-organized line of centrifugal pumps that is divided into three areas: pure media, contaminated media, and shredder pumps. Depending on the chip load, the two latter pump types can be used to transport a mixture of chips and cooling lubricant to filters/separators. After cleaning, pure media pumps supply machines with clean cooling lubricant.
KNOLL offers its centrifugal pumps – with all models as vertical submersible pumps – in five different configurations. The TG pumps are suitable for pure media – the cooling lubricant may still contain some residual contamination. The characteristic feature of these pumps is a closed impeller, which ensures good suction properties. At the EMO trade show booth, KNOLL will exhibit the two sizes TG 25 and TG 50, which have been completely redesigned and optimized in many respects.
Among the essential improvements are the use of standard motors – specified in cooperation with Siemens – that come in various performance classes. Based on the positive experiences that KNOLL has already had with these so-called "world motors" in its high-pressure pumps, the pump specialist has extended the use of these motors to all centrifugal pumps. Because KNOLL's cooling lubricant systems are used around the world, KNOLL places special value on ensuring that each world motor fulfills a wide variety of country requirements – whether IE3 in Europe or NEMA Premium Efficiency (UL/CSA configuration) in the USA. In addition, these drives bear the China Energy Label. Thanks to standardization, they are available with power up to 30 kW.
KNOLL also offers comprehensive support for the centrifugal pumps in order to ensure especially energy-efficient use. They can be equipped with a frequency inverter (0.75 to 7.5 kW), which is recommended with changing requirements for delivery rate and pressure. The frequency inverter is mounted on the motor's terminal box to save space. Advantageous also is that with this special equipment, KNOLL's control expertise is incorporated into the control. This guarantees that performance is optimally adjusted to requirements – which contributes to considerable energy savings. For larger systems, the delivery rate can be divided across several pumps that can be switched individually.
The innovations include constructive details, process improvements, easier mounting, and longer life spans. A few examples: the pressure pipe is configured as a plug-in pipe system and makes screw connections superfluous. The shaft bearings have also been optimized. They now feature ceramic slide bearings (SiC), which provide great stability, quiet running, and low wear. The wear resistance of the pumps has been improved further as well. For heavily-used components, KNOLL uses hardened cast and steel materials. This makes the KNOLL cooling lubricant pumps extremely robust.
This is especially important for the contaminated media pumps, which include the TF (with free-stream impeller for coarse, contaminated cooling lubricant), TS (with helical impeller for contaminated cooling lubricant with air), and TSK (with semi-open radial impeller for contaminated cooling lubricant with short chips) configurations.
The TSC shredder pumps, which KNOLL offers for the conveying of cooling lubricant with long aluminum chips, are subjected to the harshest conditions However, the TSC pumps are not suitable for media with long steel chips. Separate chip reducers are required for these; KNOLL also has these in its product lines.
About five years ago, KNOLL developed the TSC 65 shredder pump, which has a semi-open radial impeller and a cutting device that reduces long aluminum chips to a pump-friendly dimension of approximately 10 to 20 mm. After its successful start, KNOLL has expanded this pump line to the somewhat smaller TSC 50, which will be presented for the first time at EMO 2017.
This way, KNOLL has especially optimized economy with the use of these shredder pumps. Although the TSC 65 can be used starting with delivery rates of 200 l/m, it demonstrates its true strengths starting only at 500 l/min. The optimal use of the TSC 50 is between 300 and 500 l/m, so that many cooling lubricant systems can be operated more economically with it.
Other performance features of the new TSC 50: it manages a delivery rate Q of up to 600 l/m with a maximum delivery head of 20 m. The chips may be up to 0.5 mm thick, and the chip load may be up to 7 g/l. A high air percentage of up to 25 percent is also permissible. KNOLL leaves the selection of the motors to the customer and leaves open various design possibilities with the pump plate.
The modular system that KNOLL prefers is also featured in the TSC 50. As for all centrifugal pumps, the same world motors and frequency inverters are used; as many components as possible, including pipes and bearings, are identical across configurations. Built so that it is nearly identical to the TSC 50 is the new contaminated media pump TSK 50. It is only lacking the shredder; for this, it has an inducer that reduces the risk of cavitation. Thus both pumps can be exchanged 1:1, and even modification is possible.
The concern behind the modular system and ensuring that as many parts as possible are identical is an essential customer benefit: KNOLL keeps all components in stock, which minimizes delivery times. For the TSC 50, delivery times are currently between one and two weeks – this is an almost unbeatable value.