WTMA Common Tools and Fasteners 3 — Questions and Answers
Question 1: What is the function of a lock washer placed under a bolt head?
- Increase the clamping surface area only
- Prevent the fastener from loosening due to vibration (Correct answer)
- Seal against fluid leakage
- Reduce the torque required
Correct answer: Prevent the fastener from loosening due to vibration
Lock washers (split or toothed) bite into the fastener and mating surface to resist rotational loosening from vibration.
Question 2: When would you use a reamer instead of a drill bit?
- To create a hole in hardened steel
- To enlarge and precisely finish an existing hole to exact size (Correct answer)
- To cut threads inside a hole
- To countersink a bolt head flush
Correct answer: To enlarge and precisely finish an existing hole to exact size
A reamer is used after drilling to bring a hole to a precise final diameter with a smooth finish.
Question 3: A hex key (Allen wrench) engages which type of fastener drive?
- External hex head
- Internal hexagonal socket (hex socket) (Correct answer)
- Phillips recess
- Torx 6-point star
Correct answer: Internal hexagonal socket (hex socket)
Hex keys fit into internal hexagonal (6-sided) recesses found in set screws, socket head cap screws, and similar fasteners.
Question 4: What does a higher grade number on a metric bolt (e.g., 10.9 vs 8.8) indicate?
- Larger thread pitch
- Higher strength and hardness (Correct answer)
- Corrosion-resistant coating
- Finer thread specification
Correct answer: Higher strength and hardness
Higher metric bolt grade numbers (like 10.9 or 12.9) indicate greater tensile strength and hardness compared to lower grades like 8.8.
Question 5: Which type of pliers is best suited for gripping rounded objects like pipes?
- Needle-nose pliers
- Slip-joint pliers
- Tongue-and-groove (Channellock) pliers (Correct answer)
- Locking (Vise-Grip) pliers
Correct answer: Tongue-and-groove (Channellock) pliers
Tongue-and-groove pliers (like Channellocks) have curved jaws and an adjustable pivot that provide a wide opening and good grip on rounded objects.
Question 6: What is the purpose of anti-seize compound applied to fastener threads?
- Increase friction to prevent loosening
- Prevent corrosion and galling so the fastener can be removed later (Correct answer)
- Act as a thread sealant against fluids
- Increase the torque capacity of the fastener
Correct answer: Prevent corrosion and galling so the fastener can be removed later
Anti-seize compound prevents corrosion, galling, and seizing between threads so fasteners can be removed easily after long service.
Question 7: A cold chisel is typically struck with which tool?
- Rubber mallet
- Ball-peen hammer (Correct answer)
- Dead blow hammer
- Plastic-faced hammer
Correct answer: Ball-peen hammer
A ball-peen hammer's hardened steel head is used to strike cold chisels, punches, and other hardened metal tools.
WTMA Common Tools and Fasteners 3
What is the function of a lock washer placed under a bolt head?