Plywood is obtained by gluing wooden sheets at a pressure of:
The Making of Plywood
Plywood is an engineered wood product made from thin layers, or "plies," of wood veneer that are glued together. Each adjacent layer is rotated up to 90 degrees to one another (cross-graining). This technique gives the final panel immense strength in all directions and resistance to warping. The process of bonding these veneers requires both adhesive and significant pressure in a hot press.
📝 Detailed Analysis of the Options
The standard industrial pressure for manufacturing plywood typically ranges from 70 to 140 N/cm² (approximately 100 to 200 psi). This pressure ensures that the adhesive spreads evenly and the veneers bond tightly.
(a) 100 to 150 N/cm²
This range largely falls within the accepted industrial standard. The upper value of 150 N/cm² is slightly high but still plausible for certain applications.
(b) 100 to 130 N/cm²
This range fits perfectly within the common manufacturing pressure of 70 to 140 N/cm².
(c) Both (a) and (b)
This is the correct answer. Since the generally accepted pressure range is 70 to 140 N/cm², both of the ranges given in options (a) and (b) are valid representations of the pressures used. Option (b) is fully contained within the standard range, and option (a) overlaps significantly. In the context of this question, acknowledging that both are acceptable ranges makes this the most comprehensive and accurate choice.
(d) Neither (a) nor (b)
This is incorrect, as both options (a) and (b) represent typical pressure values used in the production of plywood.
📊 Plywood Manufacturing Parameters
| Parameter | Description | Typical Value / Rule |
|---|---|---|
| Pressure | Force applied to bond veneers | 70 to 140 N/cm² |
| Plies (Layers) | Thin sheets of wood veneer | Always an odd number (3, 5, 7...) |
| Grain Direction | Orientation of wood fibers | Perpendicular to adjacent layers |
| Adhesive | Glue used for bonding | Urea-formaldehyde, Phenol-formaldehyde |
💡 Study Tips
- Odd Numbers and Right Angles: Remember the two golden rules of plywood construction: an odd number of plies, and grains at right angles.
- Pressure Range: Memorize the general pressure range of 70-140 N/cm². This will help you evaluate options in similar questions.
- Engineered Strength: Understand that plywood isn't just glued wood; it's an engineered panel designed for superior strength and stability compared to solid wood of the same thickness.