Pallet boss or checker made of pressed timber is a composite material of the required cross-section. It began to be used in pallet production relatively recently and in view of its unique characteristics and properties, it is gaining the market rapidly. However, if we note the high similarity of this material with chipboard, it can be argued that the history of the pressed timber used in the production of pallets goes back to the creation of chipboard at the end of the 19th century.
Pressed timber production technology
The liquidity of checkers made of pressed timber is explained by the fact that free waste from woodworking industries is used as the main filler. This can be either sawdust after a band or disc saw, or wany parts of the wood ground on knife, hammer and disc machines. Moreover, in the production process, waste from furniture and moulded strips can be used without additional drying. Our company does not set limits for the minimum particle fraction, as there is a successful experience of working even on wood dust, yet it sets the maximum size for sawdust: 3 mm in diameter and 9 mm in length; and 5 mm*5 mm for chips with the thickness of no more than 2 mm.
Regardless of the raw material, the production technology of pressed timber in general is as follows:
- Woodworking waste is crushed to a homogeneous fraction and dried to the required humidity. For the maximum humidity indicator, we take 12%. It should be noted that the reduction in raw material moisture has a positive effect on the final productivity of the machine
- Dried sawdust is mixed with the urea binder in a special mixer in the proportion set by the production technologist. Urea-formaldehyde resin UF-15 and related compounds are mainly used as a binder.
- After mixing the mass is loaded into the containers of the agitators, from where it enters the heated dies. It is worth noting that the temperature in the die will differ from one manufacturer to another, since the cross-section of the boss and the speed of its movement inside the die varies significantly.
- The output density of the pressed timber is achieved by adjusting output ladders. The ideal indicator for pallet checkers is considered to be 600 kg/cubic meter, since it is the closest to the classic dried wood indicator
- On exiting the machine, the bar is cut to the specified size to facilitate storage on a pallet and transportation to the customer.
- It is important to understand that the production process and the final result may differ slightly from the one described, depending on the cross-section of the pressed timber block, the binder and the additives used.