Screw-driven linear slides let Deena, a robot, quickly prepare samples to be tested for mercury and other metals.
Deena, from Thomas Cain Inc. in Omaha, Neb., is essentially an X-Y-Z robot that uses three different versions of the RGS 10000 slides leadscrews from Kerk Motion Products Inc. Kerk, Hollis, N.H.
Accurate positioning is particularly critical in one of the last steps in preparing samples. Here, samples are filled with a precise volume of deionized water to replace water that evaporates during the preparation process.
Designers felt traditional leadscrews wouldn’t be precise enough. Instead, they went with the Kerk Rapid Guide Screw (RGS) slide. It is compact and has a wear-compensating, antibacklash carriage in an aluminum guide. A precisionrolled, stainlesssteel leadscrew drives the car r iage. And there were no concerns about end-to-end tolerances and fit because the RGS 10000 bolts to the sheet-metal frame.
Deena’s X-axis positions a dispenser head over the sample vials. Its linear slide is 28-in. long with a 1-in. pitch (e.g., 1 in./rev). It is relatively thin, which adds torsional stiffness and stability while the built-in mounting base provides support over its entire length.
The Z axis is actually an elevator that lowers samples into a heater. It uses two 8.5-in.-long slides with a 0.5-in. pitch. The two slides are linked by a chain and operate concurrently. An optional dispensing syringe also uses the 8.5-in. slide.
Deena lets technicians cut the time they spend preparing samples from 4 hr to 30 min.