Buehlmann, Ragsdale, Gfeller

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Buehlmann, Ragsdale, Gfeller

• A spreadsheet-based decision support system for
  wood panel manufacturing
• DSS 29(2000) 207-227

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Outline

• What is the product and why is it important?
• What is the purpose of the DSS?
• Constraints
• Variables

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Medium Density Fibreboard (MDF)

• MDF is a waste-wood product that is made with
  fine wood fibre.

http//www.lowes.com
4
Particleboard

• Particleboard is a waste-wood product that is
  made by mixing sawdust with adhesives. Although
  it will not bow or warp like plywood, it can
  swell and become unstable when exposed to water.

http//www.lowes.com
5
Oriented Strand Board (OSB)

• OSB is an engineered wood product that is made
  with flakes or large chips of wood. The panels
  are formed from layers or plies glued together
  with their strands at ninety-degree angles to one
  another. The cross orientation of the layers adds
  strength to the panels and makes OSB well-suited
  for use as a structure board.

http//www.lowes.com
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Importance

• Increasing population and increasing per capita
  consumption ? possible future gaps in supply.
• Wood panel manufacturers face increased demand
  for their raw material and upward pressure in raw
  material prices.

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Construction

• Small pieces of wood
• Softwood or hardwood
• Logs, chips, shavings, sawdust
• Prices fluctuate
• Substitution possible
• Organic binder

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Purpose of DSS

• Optimise raw material mix with respect to cost
  while maintaining adequate product quality.
• More formally
• Use linear programming to find the minimum cost
  raw material mix while respecting all quality
  related constraints.

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Quality influenced by

• Raw material composition
• Wood species used
• Type of material processed
• Density profile within the thickness of the board
• Moisture content of raw and processed material
• Type and quantity of binder
• Press time
• Surface finishing

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Typical constraints

• Availability of given wooden raw material
• Specific panel quality requirements
• Processing capacities, e.g. capacity for logs and
  capacity for sawdust
• Validity of mixture

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Example problem

• Two products to be produced
• Furniture grade particle board (smooth surface)
• Construction grade particle board (mechanical
  properties)
• Multiple layers per panel
• Six sources of raw materials

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Variables

• Production
• 2 panels (furniture/construction)
• Raw materials available
• 8 raw materials
• Raw materials quantities
• 2 panels production quantity
• 2 panels overall density
• 2 layers density for each panel

• Quality restrictions
• 11 quality restrictions/layer
• Production capacity
• 9 equipment capacities
• Costs
• 8 raw material costs
• 8 processing costs
• .
• (Fig 1 on p209)

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Constraints in the example

• No raw material quantity can be a negative number
  (32)
• Capacity requirements lt 100 (9)
• Quality constraints (11 per layer 44)
• Raw materials quanities (15)

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DSS requirements

• Preliminary data conversions
• Guidance for new users
• Rapid use for experienced users
• Access limited according to job task
• Logs of users, changes, etc.