Research Brief #6

RAM (Rough Mill Analysis Model)>
Louisiana Forest Products Development Center
Louisiana State University
Baton Rouge, LA

Research Objectives

Develop user-friendly simulation software for both crosscut-first and rip-first rough mill production systems.

Synopsis of Results

Rough mill simulation software enables to design new or model existing crosscut-first and rip-first operations and observe influence of input material, cutting order, plant layout, processing and transportation times on parameters such as yield, throughput, processing time and machine utilization.

Program Description :

• The simulation model runs on IBM PC-compatible computers.
• The simulation model can be easily modified to accommodate various rough mill layouts. It is equipped with a user-friendly interface to eliminate the need for user programming and simulation skills.
• The model contains a realistic board entity generator comprised of a database of digitized boards and a program simulating cutup of these boards for both crosscut-first and rip-first rough mill systems.
• Cutting order describes length, width and number of parts information.
• Part quality can be clear two face (C2F), clear one face (C1F), or sound two face (S2F). Cutting order information requires descriptions of part lengths, widths and quantities.
• The user can enter a feed rate for the unstacker; select the number of parallel machines for each operation; enter transportation times, machine processing times, and surge deck capacity for each machine; and enter sorting operation times.
• To provide lumber entities for the RAM simulation, lumber from the database is randomly sampled to produce the user specified grade mix. This grade mix may be comprised of a single grade or any mix of the six grades. It is possible to use randomly sampled lumber from a previous run or to use a new random sample of lumber. This insures that any difference between simulation runs is caused by changes in input parameters and/or dynamic changes in the system rather than by variation in the board entities.

Conclusions

A user-friendly rough mill simulation software package called RAM was developed. Individuals with no knowledge of simulation can use this RAM software to model current or proposed rough mills. A database of digital lumber descriptions allows the generation of realistic entities to flow through the modeled rough mills. Ram was validated in both the crosscut-first and the rip-first rough mills. Validation results show that RAM closely describes yield, processing time, and machine utilization of modeled rough mills.

Researchers

Rado Gazo, Post-Doctoral Researcher
Louisiana Forest Products Development Center
LSU Agricultural Center

Philip H. Steele, Professor
Mississippi Forest Products Laboratory

Target Group

Secondary wood manufacturers.

Methodology

Rough mill yield, throughput, processing time and machine utilization can be determined by simulating the material flow in the rough mill. The RAM (Rough Mill Analysis Model) is a process oriented simulation software. The user describes the rough mill operation, and RAM then simulates the flow of the specified lumber grade mix through the model rough mill in real time. Boards for the simulation are randomly sampled from a digitized database of lumber. A computer program simulates a three-stage rough mill lumber cutup by both the crosscut-first and rip-first systems. For the crosscut-first system, these stages are crosscutting, straight-line ripping, and salvage crosscutting. For the rip-first system, the three stages are an all movable blade gang ripping, crosscutting, and salvage straight-line ripping.