In timber engineering and wood products: For manufacturing structural plywood panels, how are the wood veneers laid with respect to the grain of adjacent plies to obtain high dimensional stability and strength?

Introduction / Context:
Plywood is an engineered wood product made by bonding thin wood sheets (veneers). Its hallmark is improved dimensional stability, reduced splitting, and nearly equal strength in two directions. This question checks whether you know the correct orientation of veneer grains in adjacent plies, which is the key to plywood performance.

Given Data / Assumptions:

• Plywood comprises an odd or balanced number of veneers.
• Each veneer has a primary grain direction.
• Adhesives and hot pressing are used for bonding.

Concept / Approach:
Orthogonal placement of grains in adjacent veneers creates a cross-laminated composite. Cross-lamination averages anisotropic wood properties, reduces swelling/shrinkage in any one direction, and enhances resistance to splitting. It also improves panel stiffness and strength balance, particularly important for floors, formwork, and sheathing.

Step-by-Step Solution:

Verification / Alternative check:
Design codes and manufacturing standards specify cross-laminated construction (grains at right angles) for structural panels. Visual inspection of quality plywood shows alternating face and core grain directions at 90°.

Why Other Options Are Wrong:

• Parallel: would behave like thick lumber, losing the benefits of cross-lamination.
• Inclined at 45° or 60°: uncommon and unnecessary; would complicate manufacture and give inferior property balance versus perpendicular orientation.

Common Pitfalls:

• Assuming decorative laminates use the same rule; decorative faces may ignore structure, but structural plywood follows cross lamination.
• Confusing plywood with oriented strand board (OSB); the manufacturing and orientation logic differ.

Final Answer:
run at right angles