ABSTRACT
The basic requirement of these processes is quite simply to produce as efficiently as possible timber of the required dimensions having a quality of surface commensurate with the intended use. Timber of high moisture content never machines as well as that at lower moisture levels. The cost of timber processing is determined primarily by the cost of tool maintenance, which in turn is related not only to properties of the timber, but also to the type and design of the saw or planer blade. A certain number of tropical hardwood timbers contain mineral inclusions that develop during the growth of the tree. The most common is silica, which is present usually in the form of small grains within the ray cells. The moisture content of the timber also plays a significant role in determining the life of cutting tools. Timbers containing silica are frequently avoided unless they possess special features that more than offset the difficulties resulting from its presence.
