Workshop Technology MCQ Questions & Answers | Mechanical Engineering

A slightly oxidizing flame is used in torch brazing of steel and cast iron. A stronger oxidizing flame is used in the welding of brass or bronze.

Gimlet is a small tool for boring holes, consisting of a shaft with a pointed screw at one end and a handle perpendicular to the shaft at the other

In TIG arc welding, The weld area and electrode is protected from oxidation or other atmospheric contamination by an inert shielding gas argon or helium

In sheet metal blanking, shear is provided on punches and dies so that Press load is reduced

The correct answer is (C) 46 mm.

Here's why: In drawing operations, we start with a flat, round piece of metal (the blank) and form it into a desired shape, like a cup. To determine the initial blank size, we need to consider that the volume of material remains approximately constant during the drawing process.

Imagine flattening out the cup. The area of that flattened-out material (the blank) must equal the surface area of the finished cup.

A simplified way to estimate this for a cylindrical cup is:
1. Calculate the surface area of the cup (bottom circle + side wall).

* Area of the bottom circle: π * (diameter/2)^2 = π * (25/2)^2 ≈ 490.87 mm²
* Area of the side wall: π * diameter * height = π * 25 * 15 ≈ 1178.10 mm²
* Total surface area ≈ 490.87 + 1178.10 = 1668.97 mm²
2. Calculate the blank diameter : the area of the blank circle is equal to the total surface area of the cup. * Area of the blank circle = π * (diameter/2)^2 * π * (diameter/2)^2 = 1668.97 mm² * diameter/2= sqrt(1668.97/π) = 23.05 * diameter = 2 * 23.05 = 46.1 mm
Therefore, the blank size is approximately 46 mm. In practice, a few more factors might influence the *exact* size (like material properties and thinning during drawing), but this gives a good estimate.

Option A: Hold the round bars during marking A scribing block is not meant to hold workpieces. Its design includes a heavy base and a scriber, but no clamping mechanism. For holding round bars, a V-block or other holding fixture is used. Therefore, this option is incorrect.

Option B: Check the trueness of flat surfaces While a scribing block can be moved across a surface plate to detect variations in height, this is not its primary or most accurate function. Dedicated tools like surface plates, straight edges, or dial indicators are used to check the trueness of flat surfaces. Hence, this option is misleading and not correct in the context of its main purpose.

Option C: Locate the centres of round bars This is the correct function. A scribing block, often used along with a V-block, is ideal for locating and marking the centre lines on cylindrical workpieces. By adjusting the scriber and rotating the bar, accurate centre marking can be achieved, which is essential for machining operations.

Option D: Check the surface roughness Surface roughness is determined using roughness comparators or profilometers, not a scribing block. A scribing block has no capability to measure or compare the surface finish quality, so this option is incorrect.

Conclusion: After evaluating all options, it is clear that the primary and correct use of a scribing block is to locate the centres of round bars. Therefore, the correct answer is Option C.

The cutting edge of a chisel should be Hardened and tempered
A chisel is a tool with a characteristically shaped cutting edge of blade on its end, for carving or cutting a hard material such as wood, stone, or metal by hand, struck with a mallet, or mechanical power.

A welding torch head is used to weld metals those are difficult to weld by using electrode. It can be identified by having only one or two pipes running to the nozzle, no oxygen-blast trigger, and two valve knobs at the bottom of the handle letting the operator adjust the oxygen and fuel flow respectively.
For gas welding, the pressure desired at the welding torch for acetylene is 7 to 103 kN/m².

In metalworking, a fuller is a tool used to form metal when hot. The fuller has a rounded, either cylindrical or parabolic, nose and may either have a handle or a shank.
The shank of the lower fuller allows the fuller to be inserted into the hardy hole of the anvil.

Ring gauge, is a cylindrical ring of a thermally stable material, often steel, whose inside diameter is finished to gauge tolerance and is used for checking the external diameter of a cylindrical object.