Plywood QC Inspection Checklist : Part 20 Quality Problems and Solutions in Plywood Production Process
In the production process of any kind of product, there will be some quality problems. There are many and complex factors affecting product quality, including the quality of raw materials, inadequate precision of processing equipment, or unreasonable processing arrangements. Of course, the other important reason is human factors, such as: skilled operators. Lack of training, operator’s sense of responsibility, operator’s mood fluctuation… Plywood production is no exception, there will be these situations.
In the production process, the product quality fluctuations caused by the above reasons need to be analyzed to find out, so as to solve in time to stabilize the product quality.
Quality of veneer joints
As the number of high-quality logs suitable for surface veneer is decreasing, most plywood factories adopt gluing process to improve the yield of surface veneer . The gluing quality of the sheet is related to the billet operation and plywood quality in the future. The quality problems, causes and solutions that may be encountered in gluing are as follows:
Quality problems: 1. The end of the veneer is uneven.
Reasons: improper sewing operation caused by the inconsistency of the ends of the veneers on both sides when feeding on the vertical tape splitter; or the inconsistency of the rectangle when the veneers are even.
Solution: strengthen the responsibility of operators and improve the operation technology level; when veneer is edged, there should be a benchmark, and veneer should not be cut into parallelograms.
Quality problems: 2. Too tight or too loose joints
Reasons: The inappropriate adjustment of the feeding extrusion roll of the sewing machine.
Solution: Adjust a pair of conical extrusion rollers under the working table of sewing machine to make them suitable.
Quality problems: 3. Insufficient adhesive tape
Causes: the tape is not fully wetted, the temperature of the heating roll of the sewing machine is too high or too low, and the pressure of the upper roll is not enough.
Solution: wet the tape fully with water; check the heating roll; increase the pressing force of the upper roll.
Quality problems: 4. The color or finish of the veneer is different.
Reasons: Material selection is inappropriate and the original matching is not achieved by the matching worker; the front and back of the two veneers are inconsistent, and the loose and tight sides are reversed when the splicing operation is carried out.
Solutions: Improve the technical level of operators, carry out more technical training, and strengthen the sense of responsibility of operators.
2. The Quality Problems of Blooms, the Defects, Reasons and Solutions of Blooms
Defect 1: Core-voids and overlap Joints
Reasons: improper placement of the zero veneers during slab assembly; core plate dislocation caused by collision during slab moving.
Solution: Core board coated with glue should be put in place for a while before billet formation; after billet formation, it should be pre-pressed so that the billet is initially bonded together and not easy to shift; and the technology level of billet formation is improved.
Defect 2: Edge missing and uneven edge of slab
Reasons: the length of core plate is insufficient, the billet is not operated in accordance with the principle of “one side at one end”; the edge of the surface plate is defective.
Solution: Strictly control the length of core board and the size of table board when purchasing; have a right angle base edge when forming billet; strengthen production management, improve the skill and responsibility of operators. Use skilled workers as much as possible.
3. Quality Problems and Solutions of Pre-pressing
In the plywood production process, the quality problems of the pre-pressing process are mainly reflected in the unsatisfactory pre-pressing effect, the pre-pressing slab can not be formed, the pre-bonding effect can not be achieved, or the phenomenon of core separation after pre-pressing occurs. The defects, causes and solutions are as follows:
Defect 1. Pre-pressing effect is not ideal, and there is no good bonding between veneers.
Reasons: the viscosity of prepressing glue is not enough; the prepressing time is not properly mastered; the thickness of the plate is too large for one-time prepressing