Designer's Corner

Cam roller guide

Linear bearings like high loads, but not high speed. Beyond five or six m/sec, recirculating carriage balls can pop from the load zone as they round a track's 180-degree bend.

Cam roller guides raise the speed limit. Instead of a profiled rail, the carriage rides on two precision steel shafts. Four cam rollers, each rotating on a sealed radial bearing, preload the carriage for minimal slippage.

Belt driven and lubricated for life, the compact design permits travel speeds up to 10m/sec, and accelerations in excess of 50m/sec².

Mark Simpson, Star Linear Systems, 14001 South Lakes Dr., Charlotte, NC 28273, 704-583-4338.

Fluidized bed

Slurry enters the Lites-Out^TM Classifier via a central feed well and enters a settling chamber. Clean water injected to a plenum under the settling chamber permeates a membrane and flows upward, through the settling chamber, and discharges over an overflow weir, typically to a dewatering screen. The interaction of the rising clean water and settling solids creates a fluidized bed. In turn, the fluidized bed inhibits the settling of light material and allows heavier particles to pass to the bottom of the chamber.

Located near the top of the zone of fluidized solids, a sensor monitors the slurry's specific gravity and opens discharge valves when a set point is reached. Swift discharge of solids produces a downward motion of the fluidized bed, accelerating separation of the solids. When the discharge valves close, the rising current of clean water dilates the fluidized bed, enhancing stratification of materials by specific gravity.

Karen Phillips, Linatex, Inc., 1550 Airport Road, Gallatin, TN 37066, 615-230-2100.

Dispensing valve

For higher yields when spin-coating audio, optical, and video discs, the Model 752V valve provides drip-free dispensing of UV-cure lacquers and other fluids. It provides consistent dosing that ensures uniform coating thickness. Clean fluid cutoff keeps lacquer off stacking rings and other surfaces.

Instead of seals, the valve employs an inert diaphragm that isolates its actuator from the dispensed material. Input air acts on the valve's piston, causing the diaphragm to open and allow pressurized fluid to flow. Valve open time can be as brief as 20 milliseconds. Opening stroke ranges from 5 to 25 mils, which allows fast shutoff. Different tip configurations are available to meet the requirements of a range of applications.

Art Tausek, EFD Inc., 977 Waterman Avenue, East Providence, RI 02914, 800-556-3484.