Lift uses actuating screw to create stable rise
Precise movement is a way of life for satellites, and at a Boeing manufacturing facility just outside Los Angeles International Airport, the precision begins on the very first trip a completed satellite takes. The trip, all of 3 feet, is from the assembly deck to the main floor on the platform of a custom designed vertical lift.
Designed to move very sensitive loadPfls, the lift uses an actuating screw to elevate an 18.5-foot by 20-foot platform without the subtle bounces or deflections that can occur with a hydraulic or mechanical lift. The satellites made at the facility range in size from 10 feet to 20 feet in diameter, with heights up to 60 feet and weights up to 60,000 pounds. They are assembled in a cleanroom environment before the 80,000-pound capacity lift transports satellites and/or component parts from the assembly deck to a testing area and finally to shipping.
The 3-foot trip takes approximately 3 minutes in each direction, with horizontal step displacements of no more than 0.01 inches during vertical movement, and horizontal variations of less than 0.02 inches over any 10 feet of travel.
A variable speed drive is installed on each of the motors, ensuring that each motor starts and stops smoothly and moves at a steady, coordinated speed. The screws are also electronically synchronized to make sure the motors are in the same position on each screw, keeping the platform perfectly level. If the screws become out-of-sync, an audio alarm is triggered.
The screw lift replaced an older hydraulic lift, providing smoother movement, more stability and control, and a reduced likelihood of product contamination by hydraulic oil.
Read more from the 2013 Casebook.