LINK Systems 5100-8 Tonnage & Analog Signal Monitor - Manual (Page 65)

Doc #: L-802-1110 Page 63 Rev. 02
7 CALIBRATION
Calibration of the tonnage monitor consists of achieving a known load on the machine and adjusting the
installed monitor so that the known load is displayed correctly. The known load used during calibration
should be at least 50% of rated machine load and preferably 100% of rated machine load. On straight
side machines with tie rod construction, it is always advisable to use loads of 100% of machine rating in
calibration when strain links are mounted on the uprights (compressed by the tie rods). False load
readings can be generated if a tie rod loses enough tension that the upright is released from compression
before full load is reached. This condition can be detected during calibration if 100% of machine rating
load is used.
Load cell(s) are generally used to provide the known load for calibration. The load cell(s) are placed in
the machine point of operation (normally with tooling absent) and a combination of shimming and shut
height adjustment is used to generate the desired load to be used for calibration. The machine must be
cycled, so that the slide strikes the load cells at the bottom of the stroke to generate the load.
Single or multiple load cells can be used to load the machine to the value used for calibration. When a
single load cell is used for calibration, it should be centrally located under the machine slide. When
multiple load cells are employed for calibration, they should be located in a geometrically symmetrical
pattern with respect to the center of the machine slide. The preferred procedure is to place a single load
cell directly under each connection to the slide from the crankshaft.
WARNING: Do not exceed the point loading of the ram specified by the press
manufacturer! It is recommended that steel plates at least one inch thick
and of at least 2 inches greater lateral dimension than the load cell contact
surfaces be placed both under and over the load cell to help distribute the
load and avoid load cell impressions in the slide or bolster material. All
plates or parallels should be symmetrically placed relative to the
centerline of the load cells, and plates and parallels used for each load cell
stack should be similar in dimension to those used in other stacks.
When multiple load cells are used, each load cell should be of the same physical dimensions and load
rating. The load cells must be shimmed as necessary to provide equal loads on each cell. The
combination of geometrically symmetrical location and equal loading for load cells will produce a total
machine load equal to the sum of the loads on each individual load cell and will simulate a single central
load.
NOTE: Incorrect gib adjustments, and/or severe bearing wear in the slide drive system
can cause the slide to cock and generate significant forces against linear guides
or gibs. These non-symmetrical forces can void the assumption of central
loading and introduce some error in the calibration procedure.