Workshop Technology MCQ Questions & Answers | Mechanical Engineering

A lap joint or overlap joint is a joint in which the members overlap. Lap joints can be used to join wood, plastic, or metal.
Lap joints are employed on plates having thickness Less than 3 mm

Thermit welding is a welding process that employs molten metal to permanently join the conductors.
The process employs an exothermic reaction of a thermite composition to heat the metal, and requires no external source of heat or current.
Thermit welding is often used in replacing broken gear teeth, repairing broken shears and joining rails, truck frames and locomotive frames etc.

Materials are limited to ductile materials because the threads are cold formed. .
Also, materials with good deformation characteristics are necessary for rolling; these materials include softer (more ductile) metals and exclude brittle materials, such as cast iron.

Cope and Drag refer to the two halves (top and bottom, respectively) of a Pattern or Mold that is used in the Green Sand Casting Method.

Materials used. Typically, materials used for pattern making are wood, metal or plastics. Wax and Plaster of Paris are also used,
Sugar pine is the most commonly used material for patterns, primarily because it is soft, light, and easy to work

A riser, also known as a feeder, is a reservoir built into a metal casting mold to prevent cavities due to shrinkage.
Most metals are less dense as a liquid than as a solid so castings shrink upon cooling, which can leave a void at the last point to solidify.

Submerged arc welding (SAW) uses a pool of molten metal that is formed beneath a blanket of granular flux.

The flux covers the arc and molten pool, preventing contamination from atmospheric gases like oxygen and nitrogen.

This method provides deep penetration, high quality, and efficiency in welding thick materials.

Carbon arc welding, TIG welding, and MIG welding also involve an arc, but they do not use the same submerged molten pool process as SAW.

Hence, the welding method that uses a pool of molten metal is Submerged arc welding.

A casting defect which occurs due to improper venting of sand is known as Blow holes

The correct answer is (C) Steel.
Here's why:

What is a Riser?
A riser is a reservoir of molten metal connected to the casting.
Its main job is to compensate for shrinkage that happens as the metal cools and solidifies.

Why different materials need different sized risers:
Different metals shrink by different amounts when they cool down from liquid to solid.
The greater the shrinkage, the bigger the riser needs to be to feed the casting and prevent voids (holes) from forming inside.

Why Steel needs the biggest riser:
Steel has the highest shrinkage rate among the given options (Aluminum, Cast Iron, Copper).
This means it shrinks the most when it solidifies.

Cast iron actually expands slightly during solidification, making it need the smallest riser.
Aluminum and Copper shrink, but less than steel, so they require risers smaller than steel's.

In short: Because steel shrinks the most as it solidifies, it needs the largest riser to supply enough extra metal to prevent defects in the final casting.

A hacksaw blade is primarily identified and ordered by its length.
Think of it like buying a piece of wood – you need to know how long it is!

Here's why the other options are less important for initial specification:

Option B: Material: While the material (like high-speed steel) is important for performance, it's usually a secondary specification.
Option C: Width: The width is generally standardized, and not the first thing you'd use to specify a blade.
Option D: Number of teeth: The number of teeth (or TPI - Teeth Per Inch) is also important for the type of material you're cutting, but again, length is the primary identifier.

So, when you go to buy a hacksaw blade, you'd typically ask for a "12-inch blade" (length) first, then specify the type of material and TPI depending on your needs.