The Importance of Gypsum Board Line Alignment – Part 1, highlights some of the areas within the board line where misalignment can cause serious production issues. In Part 2, we review the steps required to inspect and align a board line and provide a guideline for alignment tolerances.
Step One: Perform Overall Machine/Centerline Survey
The first step in preparing for a gypsum board line alignment is to perform an overall machine/centerline survey. This survey captures the alignment condition of your board line in three dimensions by obtaining centerline data and level and square conditions on select components throughout the line.
The centerlines of the following components are inspected and documented while performing the survey:
♦ Top and bottom paper unwind stations
♦ Upper and lower paper web pull stations (S-Wraps)
♦ Forming plate
♦ Head and tail pulleys of each forming belt section
♦ Infeed and out feed ends of the live roller section
♦ Knife unit
The components that are surveyed for level and square conditions are:
♦ Upper and lower paper paths through forming station
⇒ Top and bottom paper unwind stations with core shafts in operating position
⇒ Upper and lower paper web pull stations (S-Wraps)
⇒ Forming plate support posts
⇒ Forming plate for level and square and profiled for flatness
⇒ Paper guide plate pivots
♦ Forming belt conveyors
⇒ Head and tail pulleys of each forming belt section
⇒ Top belt support roll immediately above each conveyor support leg (this provides a general look at the level/elevation condition of the forming belt section)
♦ Live rollers
⇒ Lead-in and lead-out rollers as well as one immediately above each conveyor support leg for level, square and elevation
♦ Knife unit
⇒ Entire unit for level and square as well as frame side pieces for plumb/parallelism
Step Two: Install Offset Machine/Centerline Baseline
After reviewing the inspection data, the second step of the process is to install an offset machine/centerline reference baseline consisting of Stainless Steel Target Bushing (SSTB) monuments. In most cases, the overall machine baseline is installed at a convenient dimension from the machine centerline and parallel to a line established by the centerline of the forming plate and the centerline of the knife unit. Note: Based on the total length of the board line, the offset baseline may require the installation of 15 or more SSTBs.
Step Three: Realignment of the Board Line
In addition to realignment of the components that were surveyed during Step 1, additional time should be scheduled for a more in-depth inspection and realignment of nearly all rolls, guides, and forming surfaces of the board line including all paper carrying rolls within the upper and lower web paths, the creaser unit, forming station rolls, return idler rollers and forming belt frame work.
General Alignment Tolerances
As a guideline, the following alignment tolerances can be utilized for the realignment effort:
♦ Paper rolls – aligned within +/- 0.015” for level to earth and perpendicularity to the machine centerline
♦ S-Wraps and take-up rolls should be aligned within +/- 0.015” for both attributes
♦ Forming plates should be aligned level to earth and perpendicular to the machine centerline – the plate should be aligned flat within 0.005”
♦ Elevation deltas between the forming plate and the top of the first forming belt at the tail pulley to be set per the plant’s recommendation
♦ Head and tail pulleys should be aligned level to earth and perpendicular to the machine centerline within +/- 0.015”
♦ Elevation deltas at the breaks between forming belt sections and the live roller section should be maintained within +/- 0.015”
♦ Table rolls and live rollers should be aligned to a tolerance of +/- 0.015” for both attributes
♦ Knife units should be aligned within +/- 0.015” for both attributes
If you would like more information on how to increase efficiency, minimize waste and improve product quality through the alignment of your gypsum board line – please contact us to schedule a site visit to your facility.