Two major operations are involved in the production of veneer sheets.
These are:-
a) Preparation of logs.
b) Veneer manufacturing.
a) Preparation of Logs
This involves two unit operations, namely: cutting of logs and cooking or steaming of logs. Logs stored in a pond are conveyed to the factory yard and are cut by the chain saw to the desired length for feeding to the veneer lathe or to the length of the veneer sheets to be produced. In the operation of cooking or steaming high-density logs are pre-treated by cooking vats or steam chambers because they are hard and frequently too resinous to permit fresh cutting.
b) Veneer manufacturing
This process involves the following unit operations:
1) Veneer cutting
2) Green veneer clipping
3) Veneer drying
4) Veneer preparation
1) Veneer cutting - The method of rotary cutting is used to produce veneer sheets.
In automated mills, log chargers with log centering devices are usually installed for speedily, automatic feeding of log to the veneer lathe. As the log is centered by the centering device before feeding, it can immediately be fixed on the spindles of the veneer lathe and peeled in an endless sheet by utilization veneer reeling and un reeling machines. The speed of cutting and reeling is fully synchronized. Full reels are so stored on the deck of the system. The “edge-grain” veneer” is then cut by the veneer slicer, which slices across the grain of the log.
2) Green Veneer Clipping: - The sheet of green veneer peeled by the veneer lathe is cut by veneer clipper (automatic or manual) into the desired dimensions. Full rolls of the reeling machine are transferred to the unreeling unit, and the veneer is unrolled and cut by the veneer clipper.
3) Veneer Drying: - In order to ensure the maximum bonding effect of adhesive, veneer sheets must be dried adequately before gluing them together. The moisture content of veneer sheets is the most important factor in gluing. There are two types of veneer dryers, - namely roller and continuous veneer dryers.
4) Veneer Preparation:- Narrow strips of veneer are joined together into full size by the following methods.
Veneer Jointing - The edges of veneer sheets are cut straight for precise jointing. The Arisun Clipper or the veneer guillotine jointer is used for this purpose.
Veneer Taping - The veneer taping machine is used to join the veneer edge to edge to prescribed dimensions.
Veneer Edge Gluing – The veneer edge gluer is used for continuous glue – coating and splicing of the edges of veneer pieces which are carried with the grain at right angle to the direction of the feeding, automatically cutting the veneer to the desired length. Thermo-setting or thermo-plastic glue can be used with this machine. The veneer splicer is used to join the edges of veneer with glue instead of tape and is suitable for both back and core veneer sheets. The veneer sheets thus produced are packed and ready for market.
The technological process has no any adverse environmental impact.