At the end of this module, you will be able to:
- Describe the corrugating process
- Identify and describe wet end components
- Define preconditioning and preheating
- Describe corrugating and pressure rolls
- Describe how adhesives are applied
- Describe the function of a double facer glue unit
- Describe the function of the double facer hot plate section
- Identify and describe dry end components
- Describe the function of the stacker
- Differentiate between double and triple wall corrugators
The following key questions are answered in this module:
How are the flutes in the corrugating medium created?
The medium is heated and conditioned with steam before it travels through the nip created by two corrugating rolls. The corrugating rolls have alternating ridges and grooves which mesh together like gears to form the flutes.
What is the purpose of the "bridge" which carries the single-face board from the single facer to the double facer?
The bridge provides temporary storage for the single-face board to allow for temporary changes in speed at the single facer or double facer.
Why does the double facer need a hot plate section and the single facer does not?
The double facer cannot apply as high a pressure as the single facer because it must preserve the flutes in the medium. So, to fully cure the double face bonds, the sheet must be exposed to high temperatures for a longer period of time.
What is the difference between downstackers and upstackers?
Downstackers have an elevator deck which automatically lowers as the stack builds to maintain the stack height relative to the last conveyor belt. Upstackers have a stationary deck and the last conveyor belt height automatically raises as the stack builds.
Some corrugators can produce double and triple wall board. What is required for each additional wall?
For each additional wall, the corrugator requires an additional single facer unit, bridge level, and glue unit in the double facer glue unit.
Below is a transcript of the video sample provided for this module:
The medium is fluted and glued to one of the liners at the single facer. The preheated and moistened medium travels first through the corrugating nip between the two corrugating rolls. The corrugating rolls have alternating ridges and grooves, which mesh together like gears as they meet in the nip to form the flutes in the medium. After the corrugating nip, the medium is held against the second corrugating roll either by thin metal plates called fingers, vacuums applied to the inside of a perforated corrugating roll, or a pressurized chamber that presses the medium up against a solid corrugating roll. As the fluted medium approaches the nip with the pressure roll, a glue roll applies adhesive to the outer tips of the flutes. The preheated liner enters from the other side of the single facer. It contacts the fluted medium in the single facing nip between the pressure roll and the second corrugating roll. It is the heat and pressure present in this nip that are responsible for the bond that must hold the medium and liner together until the bond can fully cure. The strength of this initial "green bond" depends on the adhesive formula, adhesive application, and time and temperature in the single facing nip.
Use the additional resources and links below to learn more about this topic: