A detailed mathematical programming model for the optimal daily planning of sawmills

Abstract

The daily production planning of sawmills is a critical task in pursuing the optimal exploitation of forest resources. Production planning determines which logs are to be processed, taking into account their characteristics with the aim of satisfying the demand for final products. Logs are turned into lumber when they are cut according to a set of available cutting patterns (CPs). The development of efficient production planning is a key factor in improving the productivity of sawmills, and mathematical modeling is a suitable technique to achieve this objective. In this paper, a mixed integer linear programming (MILP) model for optimal daily production planning in sawmills is proposed. The model involves a set of CPs for each type of log, which is obtained through an exhaustive algorithm, attaining all possible feasible CPs. The proposed approach determines the optimal number of logs of each type to be cut, the selected CPs to be used, material inventory, demand fulfillment, and other industrial and commercial issues with the objective of maximizing the firm’s benefit, in reasonable computational time, considering the size of the problem.

Wood Products Manufacturing Optimization: A Survey

“…More recently, a number of sawmills have invested in innovative production technologies relying on automated sawing systems to increase their productivity. However, they often focus on improving some limited aspects such as economic profits obtained by new sawmilling machinery [4], [10], [9]. However, for a highly efficient operation of the whole production process, various factors need to be considered in order to meet increasingly complicated market demands using limited and variable raw material resources [37].…”

“…Hence, rather than relying on human intervention, the adoption of smart autonomous and computerized systems for the process improvement of sawmills can lead to a more efficient wood product industry, as it can offer sawmills considerable technical advantages such as higher accuracy and reliability of measurements, control, and cutting [11], higher production and energy efficiency during sawing and drying phases [74], [91], [92], faster production processes [37], [4], and higher productivity and compliance [17], [57]. This process improvement usually centers around some critical steps: (a) an efficient selection and design of automated equipment such as robot-assisted sawing systems, scanning devices, automatic positioning systems for the log face, and conveyor belts, (b) monitoring the state of the process steadily, (c) the coordination between different stages of the process, and (d) continuous process quality measurement by analyzing input and output data [2], [11].…”

“…This industry provides a large set of base products for supporting the downstream value chain of different businesses such as pulp and paper, furniture, and construction [2], [3]. Wood products such as lumbers and plywood, and wood by-products and residues such as wood chips and sawdust, are among major products of forest industry accounting for a large portion of total exports of countries around the world, such as Argentina [4], [5], [6], Chile [7], [8], [9], Sweden [10], [11] [12], Canada [13], [14], [15], the United States [16], [17], [18], [19], and New Zealand [20], [21]. Despite an active participation in the value added to the industry of countries, poor or inaccurate decision-making processes over different steps of forestry planning, production and trade may lead to high production and transportation costs, losses, and eco-inefficiency.…”

“…The decision process in sawmills is generally based on the expected market demand, mill capacity, and the availability of raw materials (e.g., logs) and stored products (e.g., stored lumbers) [31]. Indeed, according to the updated order information received from the customer, and the log and lumber inventory databases, the decision-maker can decide about the selection of required log characteristics for sawing, and controlling the sawing strategy over the sawing line [4]. The decision-maker should also decide about drying, trimming, and packaging procedures for the final products (e.g., lumbers, plywood, etc.…”

Economical Assessment of the Benefits of the Supply Chain Management: A Forestry Industry Example

“…By-products and harvest residues are used in the same plant to obtain the energy required by the process. Sawmills (saw): this facility uses medium- to large-size logs for the production of boards of different sizes. For the production, cutting patterns (CPs) are used to determine the number and type of boards and the amount of by-products (bark, chip, and sawdust) that are generated per log (Figure ) (Vanzetti et al). The energy required to dry the boards is obtained in the same plant using boilers fed with by-products and harvest residues. PW facility: different products are obtained using logs of a large diameter.…”