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

Technical data:

• What was needed: A clean filling, which does not have to be sterile, but has to be very clean, and a low overall weight of the system
• Requirements: Cleanroom suitability, lubrication-free, maintenance-free, lightweight, precision, fast availability
• Material: trapezoidal lead screw nut made of iglidur® W300, trapezoidal lead screw made of material AISI 304, drylin® miniature guides
• Industry: Medical technology

 

• Success for the customer: "There are many manufacturers of trapezoidal lead screw drives," reports Christian Baumann. “With this igus® solution, we particularly like the combination of the stainless steel lead screw with the maintenance-free nut made of a special plastic.” The low coefficient of friction in dry operation and the glide surfaces of the screw drive are convincing in everyday life. Added to this are the lightweight machine elements, which in turn has a positive effect on the overall weight of the system. In contrast, speed does not play a major role in the overall process. "The processes take place within seconds," Albrecht Baumann points out. "They do not place any special requirements on the machine elements. The most important thing is the precision in feeding the vessels."

Technical data:

The operating principle is relatively simple. The reaction vessels are fed loosely and transported securely to the fully automatic system via a vibrating conveyor and cleanly brought in a row to a pick-up position. Grippers from the top remove the thin-walled vessels one by one, carefully gripping them with tongs. They then travel to a pump unit for filling before they are brought for sealing. A polystyrene box has already been provided before as a mounting. After closing, the gripper or the tongs open and the vessel falls gently into the handy upright box. The drylin® lead screw drives are used for feed mechanisms and stroke movements. The customer relies on the glide surfaces of a trapezoidal lead screw nut made of iglidur® W300 and a rolled trapezoidal lead screw made of material AISI 304.

Lead screw drives are machine elements that convert rotary movement into linear motion. The drylin® lead screw drives are always based on self-lubricating plastic nuts made of highly wear-resistant tribopolymers, thus enabling long-lasting operation without external lubrication. The fact that oils and greases can thus be dispensed with ensures the cleanroom suitability of the lead screw drives, which also score points for their particularly low coefficients of friction. Corrosion-free drylin® miniature guides also prove their efficiency during the stroke movement of the gripper or tongs. The sliding elements are installed with positive locking in the housing. This simple and effective design enables guides that are both robust and economical. "These guides in the vicinity of the gripper form another core element of the system," explains Christian Baumann. "They must function absolutely reliably in the long term." The tongs of the gripper hold the vessels, position them perfectly for filling and reliably absorb the force generated during the sealing process. Other mechanical stresses are virtually non-existent, as the polystyrene boxes are extremely light.

Go to filling system:

In 2010, the highly specialised engineering office with its five employees was approached with the request to design and construct a fully automatic IVD filling plant. Their task is to fill so-called reaction vessels accurately under cleanroom conditions with laboratory diagnostic reagents in volumes ranging from a few microlitres to about 1.5 ml. In the following 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 the examination of blood cells, joint fluids, spinal fluid or brain fluid as well as for the examination of sperm. All tests concern both human and veterinary laboratories.

1:0 for drylin® linear products

Especially in medical technology and in the laboratory area, the issue of freedom from lubricants and maintenance plays an important role. Other igus® products, such as pre-loaded linear systems, backlash-free lead screw nuts, FDA-approved materials and particle or abrasion-free materials for cleanrooms, can show their capability in this complex environment. Added to this are the requirements for freedom from corrosion, which can also be fulfilled with these systems. All products described are standard parts from the catalogue. They are usually available at short notice. Special parts are also possible if required.

It took around three quarters of a year from development to commissioning of the IVD filling system that works under cleanroom conditions. "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," concludes Christian Baumann. Manfred Rüdinger adds: "Dust is our greatest enemy. Under no circumstances may dirt be allowed during handling that could falsify tests. And in this case this is 100 percent guaranteed. “

The bionanalytic GmbH

"We have been developing and designing medical devices and system solutions for many years. The focus is on analytical medical technology," explains Dipl.-Ing. (FH) Christian Baumann of the engineering office bearing the same name in Herbolzheim. "Thereby our spectrum ranges from single devices to serial devices of small, medium and large quantities. Precision and reliability are their hallmark. As a matter of principle, we only use fully developed and proven components in order to always achieve the best possible results that prove themselves in the medical environment over the long term. " 2 "We have been developing and designing medical devices and system solutions for many years. The focus is on analytical medical technology," explains Dipl.-Ing. (FH) Christian Baumann of the engineering office bearing the same name in Herbolzheim. "Thereby our spectrum ranges from single devices to serial devices of small, medium and large quantities. Precision and reliability are their hallmark. As a matter of principle, we only use fully developed and proven components in order to always achieve the best possible results that prove themselves in the medical environment over the long term. “
 

The engineering office has been relying on polymer bearings and linear guides from igus® GmbH, Cologne for many years. There are several reasons for this: First, the focus is on freedom from lubricants and second, the reliability of the machine elements. In this context, their ease of maintenance in operation also plays an important role. If, despite everything, problems should occur, it must be possible to replace the relevant components quickly and easily. Nobody can afford long plant or machine downtimes and the resulting costs. "But in this regard, we have had only the best experience. Over the years, we have never experienced any failures in any area," says Christian Baumann.

The engineering office knows the plastic products from the ground up. "Over the years, we have been provided with many sample parts," says Christian Baumann.
 
"This is more than helpful with our complex designs, because in the run-up to a new development, by simply trying out the elements that are available we can already have a feeling of whether a component is suitable for the respective motion profiles and will probably stand up to the requirements. And if there is ever a problem or question, a phone call is enough to get quick assistance. “