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Thread technology for filling systems for reaction vessels

Lubrication-free lead screw and linear technology in filling systems for reaction vessels

In the field of medical and laboratory technology, contamination must be excluded in order to be able to make reliable diagnoses. In this fully automatic filling system for medical products from bionanalytic GmbH, trapezoidal threaded spindles with matching lead screw nuts have been installed at various points. There are also linear guides in miniature design. All machine elements are lubrication-free and have virtually no particle emissions, making them ideal for use in cleanrooms.

Profile

What was needed: linear technology components for feeding the containers and the stroke movement of the gripper
Requirements: cleanroom-compatible, free from external lubrication, maintenance-free, low weight, precision, fast availability
Industry: Medical technology
Success for the customer: The dryspin® threaded spindles and drylin® linear guides used ensure hygienically clean running thanks to the solid lubricants incorporated in the plastic. The elimination of lubricants eliminates contamination and maintenance costs. The components also score points for their low coefficient of friction, light weight and easy installation.

Products used

lead screw nut iglidur® W300

Ttrapezoidal lead screw PTGSG

Miniature guide TS-04

How the filling system works

In 2010, bioanalytic GmbH commissioned Ingenieurbüro Baumann to design and build a fully automated filling system for in-vitro diagnostics (IVD). Its task is to precisely fill so-called reaction vessels with laboratory diagnostic reagents in volumes ranging from a few microlitres to around 1.5 ml under clean room conditions. In the subsequent work step, the reaction vessels are then sealed absolutely tightly and placed in polystyrene stands, which also serve as primary packaging. These produced units are part of laboratory diagnostic test kits for analysing blood cells, joint fluids, spinal fluid and cerebrospinal fluid as well as for analysing sperm. All tests are used in both human and veterinary laboratories.

Reaction vessel filling system from bioanalytic

The reaction vessels are fed loosely and protected via a vibrating conveyor to the fully automatic system and brought neatly in a row to a pick-up position.

Grippers from above remove the thin-walled containers one by one, carefully gripping them with tongs. They then move to a pump unit for filling.

After filling, the containers are sealed. The gripper or tongs then open and the container falls gently into the polystyrene stand box, which has already been fed as a receptacle.

Problem

bioanalytic has set a number of specifications for the special liquid handling system. Firstly, the filling process must be clean, not sterile, but highly pure. Secondly, the volume of the respective reagents to be filled must reliably fulfil the specifications. And finally, automating this task is not easy.

The Baumann engineering office, highly experienced with this type of system, mastered the task with flying colours. It took around nine months from development to commissioning of the IVD filling system under clean room conditions. During development, it was important to find the right linear technology for the stroke movements of the feeders and the gripper. High speeds and high mechanical loads do not play a role here. What is important, however, is precision when feeding the containers and a high degree of cleanliness at the storage points.

Solution

The Baumann engineers, who already had very good experience with igus® products, decided directly to use our dry-running linear technology.Dryspin® lead screw technology is used in the area of the feeds and the lifting movements, which consists of the sliding pairing of a trapezoidal lead screw nut made of iglidur® W300 and a rolled trapezoidal threaded spindle made of the material AISI 304.The self-lubricating plastic nuts made of highly wear-resistant tribo-polymers enable lifelong operation without external lubrication or maintenance. The elimination of oils and greases ensures that the screw drives are suitable for cleanrooms and also score points with their particularly low friction

coefficients. Corrosion-resistant drylin® T miniature guides also prove their efficiency during the stroke movement of the gripper. The lubrication-free sliding elements are also mounted in a form-fit housing. This simple and effective design enables guidance that robust is both and economical.

Christian Baumann also appreciates the service provided by igus®:"Over the years, we have been provided with many sample parts. This is more than helpful for our complex designs, as we can develop a feeling for whether a component is suitable for the respective movement profiles and is likely to withstand the requirements by simply trying out the elements provided in advance of a new development. And if there is ever a problem or a question, all it takes is a phone call to get help quickly."

"Dust is our greatest enemy. Under no circumstances may dirt be allowed during handling that could falsify tests. And that is 100 per cent guaranteed in this case."

Manfred Rüdiger

Engineer for biomedical analysis, bioanalytic GmbH

"We knew right from the start that we would rely on the lubrication-free drylin® linear products due to the requirements on site. They have already proven themselves many times over."

Christian Baumann

Dipl.-Ing. (FH), Baumann Construction

Trapezoidal threaded spindle in reaction vessel filling system from bioanalytic

igus® Products and containers with polystyrene box

dryspin® lead screw technology sample

Your own thread pattern with bundled information

► Lubricant- and maintenance-free
► Higher efficiency
► Longer service life due to asymmetry
Resistant to media
► Quiet, vibration-free running due to rounded tooth geometry
► Service life can be calculated online

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