Give a case study of the timber processing at Border Timbers in Zimbabwe. Specify all the products t

Question: Give a case study of the timber processing at Border Timbers in Zimbabwe. Specify all the products they manufacture and their applications.

Introduction

Border Timbers is a forestry and saw milling company in

. The company operates five forest estates and three sawmills.

Border Timbers' forest estates are located in Sheba, Imbeza, Charter, Tilbury and Sawerombe.
Border Timbers' sawmills are located in Sheba, Charter and Tilbury.

Border Timbers Forestry

Of the approximately 28000 hectares of plantable area, 83% is intended for pine saw log production. New and improved pinus species are also being introduced including fast-growing P. tecunumanii and P. maximinoii. The balance of the plantable area is primarily managed for Eucalyptus grandis and E. cloeziana on both a saw log and pole rotations. E. cloeziana is highly desirable for marine applications as it is resistant to wood boring marine animals.

Harvesting Operations

Border Timber’s uses motor-manual harvesting methods with the objective of completely mechanizing harvest operations in the future. Most of Border’s harvesting is now done by energetic and entrepreneurial Zimbabwean contractors and the harvesting operations aim to optimize productivity while minimizing impacts to the environment.

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Fig 1. Felling of trees

This is the initial stage of preparing the timber for commercial use. This is normally carried out in winter, when the tree has less moisture content. In the summer months, trees can have more than 50% water content. This increased weight usually adds to the cost of transport, handling and initial preparation for the sawmill.

Initial storage The tree trunks (logs) are stored or stacked in a clearing. Sometimes logs are stored in the forest until they are needed at the sawmill. This also allows some of the ‘free’ water content to evaporate, reducing the weight of the tree / log. On arrival at the mill's storage yard, logs are sorted and stored according to species, diameter, length and end-use, etc. Sufficient quantities are stockpiled to ensure the sawmill's continuous operation, particularly during adverse weather conditions when log extraction and supply from the forests may be adversely affected.

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Fig. 2 Initial storage of trees and transportation

Transportation The logs are then transported to the sawmill, using vehicles equipped with lifting gear.

Conversion

Border Timbers currently operates two medium sized sawmills, Sheba and Charter. The sawmills are designed to cut both pine and eucalyptus saw logs. Larger diameter Pine timber is milled using frame saw machines whilst the smaller diameter material is milled on either double log edger circular saws or on state of the art chipper canter technology. Eucalyptus saw logs are sawn using either Lucas, Bandsaw or Frame saw machines depending on the log diameters.

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Fig. 3. At the Charter Sawmill

All the timber produced at the sawmills is kiln dried to a moisture content ranging from 8-15% depending on the end-users requirements. Drying schedules are drawn for each species. Eucalyptus is first air stacked for three months before being kiln dried to improve timber stability and to reduce drying defects. Kiln drying results in a far superior product compared to the “wet off saw” material often found on the market. All the timber is pressed, bundled and packaged to the highest standard before dispatch.

The sawn and trimmed timber is sorted according to thickness, width, length, quality, grade and species depending on the market requirements; such an activity may be undertaken manually or, in the case of mills where low-cost labour is not available, by mechanized sorters. Grading is a means to segregate the lumber according to the overall quality, direction of grain, presence of knots and defects, as well as general appearance, etc.

Curing

To protect the sawn timber against attack from fungi and insects, as well as to inhibit the tendency of air-dried lumber to check and split, the ends may be brushed either manually or mechanically dipped in a suitably prepared chemical solution. Wax or paint is applied to the end-grain of lumber to be air-dried, either by brush or spraying, so as to act as a sealant in order to bring about a slower drying of the extremities and hence, give rise to a more uniform drying of the lumber.

At its Nyakamete Industrial site in Mutare, Border produces both creosote and tanalith (CCA) treated poles for a variety of applications including fencing, transmission and light posts. These high quality poles are certified by the SAZ standards association.

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Fig 4. left - CCA treated poles, right - Creosote treated poles

Products and Applications

Border Timbers sales timber of various sizes to customers from its two sawmills Charter and Sheba as well as from the Paulington retail outlet. The sawn pine timber product range is ALL KILN DRIED to approximately 12% moisture content and hence making it most suitable for all wood processing applications.

References

Border Timbers [Online]. Retrieved 7 May 2017 from http://www.bordertimbers.com.
Ryan V.The Preparation Of Timber. Kiln Seasoning. 2011. Retrieved 22 April 2017 from http://www.technologystudent.com/joints/forest5a.html.
Shumba, S., 2017. Timber Notes. University of Zimbabwe, Harare,.