Lead screws, guides & plastic nuts for medical lab vessel filling systems

Application Overview:

• 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, dry-running, maintenance-free, lightweight, precision, fast availability
• Material: Trapezoidal lead screw nut made of iglide® L280, Trapezoidal lead screw made of AISI 304 material, drylin® miniature guides
• Industry: Medical technology

In 2010, the highly specialized 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 microliters 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.

Lead screw systems 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 tribo-polymers, 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-resistant 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.

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-resistant 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. “