Workshop Technology & Manufacturing Processes

Comprehensive practice flashcards covering workshop safety, marking out, hand tools, measurement and gauging, machining operations (turning, drilling, milling, shaping), casting, welding, brazing, soldering, and forging.

How does workshop safety define and distinguish between an accident, danger, and a hazard?

A hazard is a source or situation that can cause harm; danger is the potential for harm; and an accident is an unwanted event that may harm people or machines.

What is the primary difference between personal protective equipment (PPE) and machine guarding?

PPE is worn directly by the operator (such as goggles and ear plugs), whereas machine guarding is fitted to the machine to physically separate people from hazards.

Why must loose clothing, dangling items, jewellery, and untied long hair be avoided near rotating machinery?

They can catch in rotating or moving machine parts and pull the operator into the machine.

What are the two primary reasons for marking out a workpiece before machining?

1. To show the workpiece outline and the positions of holes, slots, or cuts.
2. To guide accurate positioning and setup on a machine.

What is a datum in marking out?

A datum is the reference edge, face, or point from which measurements are taken; all marked dimensions are measured from the chosen datum.

How does the rectangular coordinate system differ from the polar coordinate system in marking out?

Rectangular coordinates ($X, Y$) measure distances along two axes at right angles to each other, whereas polar coordinates ($r, \theta$) locate a point using a radius from the datum and an angle.

What is the purpose of applying engineer's blue or a marking medium to a metal surface?

It coats the workpiece surface so that fine scribed lines can be seen clearly.

What specific functions do a surface plate and an angle plate serve during marking out?

A surface plate provides a flat reference surface or datum, while an angle plate supports or holds a workpiece at a set angle.

Which marking-out tool is used specifically to hold round or cylindrical workpieces?

A V-block.

What marking-out tool is used to support and adjust a workpiece to a required position, and which tool levels work on uneven surfaces?

A jack supports and adjusts a workpiece to the required position, while a wedge supports or levels work on uneven surfaces.

What cutting tools are specified for cutting thin/light-gauge sheet metal versus thicker sheets of about $1.5\,\text{mm}$ and above?

Thin or light-gauge sheets are cut using snips (for straight or curved cuts), whereas thicker sheets (about $1.5\,\text{mm}$ and above) are cut using a hand-lever shear.

How are simple sheet-metal bends formed compared to bending larger or thicker workpieces?

Simple bends are made by holding the sheet in a vice and bending it over with a soft hammer; larger workpieces and thicker sheet-metal gauges are bent using folding machines.

Under what four workshop conditions are hand tools typically used instead of machine tools?

1. No suitable machine is available.
2. The workpiece is too large for a machine.
3. The shape is too intricate.
4. Using a machine would be more expensive.

What benefits do powered hand tools, such as powered screwdrivers and hand drills, offer over manual tools?

They reduce manual effort, increase operating speed, and reduce operator fatigue.

Why must a file always be fitted with a handle during use?

The handle prevents the pointed tang from puncturing or injuring the operator's hand and provides a safe, controlled grip.

How does a rough file differ from a smooth file?

A rough file has coarse teeth and removes material quickly, whereas a smooth file has finer teeth and produces a better surface finish.

What is the key distinction between measurement and gauging?

Measurement uses an instrument to give a numerical value for a dimension, whereas gauging uses limit gauges to perform a pass/fail check determining whether a dimension is within its maximum and minimum limits.

What are the four common checks performed using gauging techniques?

1. Straightness
2. Flatness
3. Squareness
4. Internal and external dimensions

What features of a workpiece do the external jaws, internal jaws, and depth rod of a vernier caliper measure?

External jaws measure outside diameter or thickness; internal jaws measure inside diameter or width; and the depth rod measures the depth of a hole or step.

What is the formula used to calculate the least count of a vernier caliper?

$$\text{Least count} = \frac{\text{Value of one main-scale division}}{\text{Number of vernier divisions}}$$

What is the general formula for calculating the measured dimension using a vernier caliper?

$$\text{Reading} = \text{Main-scale reading} + (\text{Coinciding vernier division} \times \text{Least count})$$

How is zero correction applied to an observed measurement when an instrument has a zero error?

$$\text{Correct reading} = \text{Observed reading} - \text{Zero error}$$

What is the purpose of the ratchet stop on an outside micrometer?

It applies a consistent measuring force to ensure repeatable readings and prevents over-tightening, which can deform the workpiece or the instrument.

How is the least count of a micrometer determined, and what is its typical value for a metric micrometer?

$\text{Least count} = \frac{\text{Screw pitch}}{\text{Number of divisions on the thimble}}$; on a common metric micrometer, it is typically $0.01\,\text{mm}$.

In machining, what is the difference between the main cutting motion and the feed motion?

The main cutting motion provides the relative movement that removes material, whereas the feed motion advances the cutting edge to remove material over the required area.

In lathe turning, which component provides the main motion and which provides the feed motion?

The workpiece provides the main rotary motion, and the cutting tool provides the linear feed motion.

What is the difference between facing and straight turning on a lathe?

Straight turning reduces the outside diameter along the length of the workpiece, while facing machines the end of the workpiece to create a flat face perpendicular to its axis.

How do three-jaw chucks, four-jaw chucks, and faceplates differ in lathe workholding?

A three-jaw chuck is self-centring and used for round or hexagonal work; a four-jaw chuck has independent jaws to hold irregular or off-centre work; and a faceplate holds large or awkwardly shaped parts.

What are the main cutting and feed motions in drilling?

The main motion is the rotary motion of the drill, and the feed motion is the linear axial movement of the drill into the workpiece.

What is the difference between counterboring and countersinking?

Counterboring produces a flat-bottomed recess around a hole, whereas countersinking produces a conical recess.

What is the purpose of reaming, and how does it differ from boring?

Reaming finishes a near-size hole to improve dimensional accuracy and surface finish, whereas boring uses a single-point tool to enlarge or correct the alignment of an existing hole.

What thread-cutting tools are used for internal threads versus external threads?

A tap is used to cut internal threads in a hole, and a die is used to cut external threads on a bar or cylinder.

What provides the main motion and feed motion during a milling operation?

The main motion is the rotary motion of the milling cutter, and the feed motion is the linear motion of the workpiece/table.

What is the difference between arbor-mounted and screw-shank milling cutters?

Arbor-mounted cutters (such as cylindrical, side-and-face, and shell-end cutters) mount on an arbor shaft, whereas screw-shank cutters (such as end mills, slot drills, and T-slot cutters) have a threaded shank that mounts directly into a toolholder.

How do shaping, planing, and slotting differ in their tool and workpiece motions?

In shaping, a single-point tool reciprocates horizontally over a stationary workpiece; in planing, a large workpiece reciprocates horizontally beneath a stationary tool; and in slotting, the tool reciprocates vertically to cut internal slots and keyways.

What does CNC stand for, and what are its main workshop advantages?

CNC stands for Computer Numerical Control. Its advantages include repeatable accuracy, consistent production, the ability to produce complex shapes, and reduced continuous manual control.

In sand casting, what are the cope and drag?

The cope is the upper half of the moulding flask, and the drag is the lower half.

What is the difference between a pattern and a core in a casting mould?

A pattern is a replica used to create the external mould cavity, while a core is an insert placed into the mould to form internal hollow spaces or passages.

What is the function of a riser in a casting gating system?

A riser is a reservoir that feeds molten metal into the mould cavity to compensate for shrinkage as the metal solidifies.

How does green-sand casting differ from dry-sand casting?

Green-sand casting uses a moist sand mixture (containing sand, clay, and water) that is not dried before pouring, while dry-sand casting uses a mould that is baked or dried prior to pouring.

What happens to the base metals in fusion welding compared to brazing and soldering?

In fusion welding, the edges of the base metals melt to form the joint; in brazing and soldering, only the filler metal melts, while the base metals remain solid.

What melting point threshold distinguishes brazing from soldering?

Brazing uses a filler metal that melts above approximately $450\,^\circ\text{C}$, whereas soldering uses a filler metal with a melting point below approximately $450\,^\circ\text{C}$.

What is the heat-affected zone (HAZ) in welding?

The HAZ is the area of base metal adjacent to the weld that does not melt, but experiences changes in structure or mechanical properties due to heat.

How does hot forging differ from cold forging in terms of temperature and force?

Hot forging is performed after heating the metal above its recrystallisation temperature, requiring less force to deform; cold forging is carried out near room temperature, requiring higher force but yielding improved finish and strength.

What is the distinction between open-die forging and closed-die forging?

Open-die forging compresses metal between dies that do not fully enclose the workpiece (allowing lateral metal flow), whereas closed-die forging compresses heated metal inside shaped die cavities to produce defined, repeatable shapes.