Economically efficient automation is an issue that is also assigned very high priority by many laboratories, universities and institutes. What they are usually looking for is an individual one-off system that matches their budget. For example, maintenance-free and lubrication-free linear robots from igus® that can be tailored to the respective requirements of design engineers enable the performance of filling tasks involving biochemical liquids. The components for this can be selected from the igus® modular system and then put together.
"Our customised systems for the complex handling of fluids and liquids are in use all over the world", says Ulf Niedergesäß, design engineer working for the highly specialised company M2-Automation from Berlin. The company develops and builds its devices for the manufacture of diagnostic systems and sample preparation with a very small dispensing volume. These are intended for use in medical research and environmental analysis - for example for medical micro-dispensing systems for the accurate contact-free ejection of chemical and biological liquids and suspensions in the picolitre and nanolitre range.
When designing a customised filling system, Ulf Niedergesäß, the design engineer responsible, decided to use a lubrication-free and therefore maintenance-free drylin® E room linear robot from igus®. The linear robots from igus® are a combination of several linear axes that together enable multi-dimensional movement. Depending on the task in hand, these robot installations are in the form of flat, line or room linear robots, none of which require any lubrication. The ready-to-connect linear robots include pre-harnessed drylin® linear modules and/or drylin® linear axes with NEMA stepper motors as well as all the components needed for self-construction of the equipment.
Before beginning to design the new system, Ulf Niedergesäß took a close look at the many suppliersof kinematic systems. His selection criteria were that the weight must be as low as possible, that the design must be a compact one and that, nevertheless, a relatively large working area should be covered. Then there was also the issue of economic efficiency. What finally tipped the scales in favour of the room linear robot from igus® room was its price/performance ratio, on the one hand, and, on the other, its flexible adaptability to the stipulated size variables. At the same time, all additional requirements such as positioning accuracy, speed and a long service life were met.
Other advantages were the tribological properties of the high-performance polymers from igus®. The high chemical and hygienic cleanliness requirements placed on installations and equipment in a laboratory environment are usually very strict. "Dirt and dust have no place in the laboratory", says Niedergesäß definitively. The use of polymer bearings in all places with moving parts make the room linear robot lubrication-free and therefore maintenance-free. "The use of lubricants in the room linear robot would have been a criterion for ruling it out. The bottom line for all our systems is that they must be maintenance-free. " For this reason, the use of igus® components and systems is also conceivable in other liquid handling systems if the positioning requirements are not too high.
The customised system for a customer from the area of bioanalytics and medical technology automatically and flexible fills different receptacles with volumes of 0.05 millilitres to 500 millilitres. At the moment, nine different types of bottle are in use, but the selection can be extended indefinitely.
One important decision-making criterion was the ratio of the effectively available floor space to the absolute size of the equipment, the reason being that space in a laboratory is usually very expensive. The external dimensions are 1,600 x 1,900 x 800 millimetres The size of the available work space is 1,105 x 525 millimetres. The compact filling system rests on rollers and can be moved about as required. It is controlled via an intuitive software user-interface that people can use without very much training.
The goal of development was to create a robust system that was easy to operate and could reproducibly dispense different volumes and viscosities at an appropriate speed with as much precision as possible. The system can be fitted out with four trays. The trays are manufactured to match the respective type of bottle. This makes it possible to fill any kind of receptacle and, if necessary, modify the system with minimum effort years later. The positioning accuracy is +/- one millimetre. At the present time, up to 1,400 bottles can be filled in one run through the system. The axis system positions the filling needles precisely in the neck of each bottle. The maximum travel speed is 300 m/s. "Previously, the entire process was carried out manually and tied up an employee", reports Ulf Niedergesäß. "It is not only the cost factor for an employee that counts but, also and above all, the quality. This is now ensured at all times, with the result that filling errors no longer occur. “
The lubrication-free room linear robot has a simple design. Two robust, horizontally aligned toothed belt axes of the type drylin® ZLW-0630 with a motor are used as the x axis. This is the appropriate solution for simple moving and positioning tasks in environments where space is restricted. The installation height is only 31 millimetres. Given a stroke length of 1,100 millimetres, of which the actual travel distance is 1,040 millimetres, the axis is a special design in terms of its length, which is normally a maximum of 1,000 millimetres. "Here, we received a flexible response to our wishes based on reliable calculations regarding the overall solution", confirms Ulf Niedergesäß. For the y direction, two 600 millimetre long, mechanically coupled, side-mounted parallel axes of the size ZLW-0630 are used. A drylin® GRQ toothed rack axis was chosen as the z axis for the dispensing module. The stroke is 240 millimetres, which is made use of over the entire height and, when necessary, can be scaled to meet other requirements at any time. This increases the flexibility of the entire system. "It is a robust, compact and economically efficient solution that performs its positioning tasks fully and precisely", says Ulf Niedergesäß in clarification. Another benefit is the quiet operation of the axes. "This was yet another thing that convinced us", confirmed the design engineer.
The accessories are also important for the filling system. The motors are stepper motors of the sizes NEMA 11, 17 and 23 with optical incremental encoders in the closed-loop control circuit. Precision inductive proximity switches were chosen as the end switches. Further igus® products such as chainflex® motor cables and plastic energy chains of the E2 series were also used in the project. "We offer a cost-effective, ready-to-connect linear robot system that is derived from the modular system and can be ordered immediately via the catalogue", explains the responsible igus® sales consultant, Benjamin Neumann. "Solutions for automation tasks where highly precise movements are not necessarily required can thus be created quickly and effectively. “
Ulf Niedergesäß makes one point clear: "For us, flexibility plays an important role. We are a small company with only ten highly specialised employees and must respond quickly to the enquiries of our customers. It is often only a few months from when we receive the order until we deliver the actual product. It is therefore important that our suppliers respond quickly to our requirements. " With igus®, everything went smoothly from the very beginning. Moreover, within a few days, the drylin® GRQ axis was equipped with a bracket that can be clamped on in different positions and whose purpose is to trigger the integrated initiator. In this way, the exact triggering position can be set and altered quickly. "This accessory, which only came on the market recently, guarantees even better precision during the filling process", confirms Niedergesäß.
Manufacturers of components and equipment entered into a fruitful symbiosis for this newly designed system. With the help of the ready-to-install and ready-to-connect mechatronic system, the filling system was built, the control systems were incorporated, the software was installed and the whole system was commissioned within a very short time. The engineering advantage of the electrically driven drylin® linear axes in the linear robot application is that they can easily be adapted to the respective travel ranges. "This makes is possible to create a one-off customised system that pays off for any end customer in the expensive laboratory environment", clarifies Benjamin Neumann.In conclusion, Ulf Niedergesäß from M2-Automation points out the central advantage of the solution. "We do not have to repeatedly re-invent the wheel but are able to make use of catalogue components. “
drylin® E is an open and modular mechatronic system. It is open because, if they wish, customers can use their own motors to drive igus® lead screws or toothed belt units. The appropriate adapters or motor flange is provided. The modular system comprises 25 different linear axes, twelve gradients or transmission ratios, appropriate cables, motor flange, 20 couplings, end switches and position switches as well as 15 different types of stepper motor from 0.5 to 6 Nm, with or without encoder and brake
Since 2003, M2-Automation from Berlin has specialised in customised laboratory automation solutions, non-contact dispensing of liquids and cell suspensions, hardware for the manufacture and processing of biochips and lab-on-a-chip devices, real-time image processing as well as equipment control and evaluation software. The M2 team includes biologists, chemists, software engineers and design engineers.
Thanks to its extensive support in matters relating to applications and technical issues, M2-Automation has acquired an excellent reputation among its customers and is a competent advisor and developer in the area of micro-dispenser technology for small and very small volumes.
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