Mechanical Properties and Terms

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Questions and Answers

What is the primary purpose of buffing in metal processing?

To improve corrosion resistance

To enhance the polish and luster of the metal (correct)

To reduce internal stresses in the metal

To increase the density and strength of the metal

What material, developed in the late 1940s, is known for its corrosion resistance and high strength?

Zirconium

Aluminum

Nickel

Titanium (correct)

Which process is used to reduce internal stresses in steel?

Quenching

Annealing

Stress Relieving (correct)

Tempering

What is the main characteristic of free-cutting steel compared to regular carbon steels?

Higher sulfur content Signup and view all the answers

What property describes a steel's resistance to softening at elevated temperatures?

Hot hardness Signup and view all the answers

In braking systems, what does the term 'backstop' refer to?

A brake that is self-locking in one direction Signup and view all the answers

What type of crane is described as having a vertical support with a horizontal swinging arm?

Jib crane Signup and view all the answers

Which type of iron is also known as ductile cast iron?

Nodular cast iron Signup and view all the answers

Which gas is typically used in the nitriding process for surface hardening?

Ammonia gas Signup and view all the answers

What is a significant benefit of using nitriding for alloy steels?

Improvement of endurance strength, 50% or more Signup and view all the answers

What is the recommended material factor for cast steel in estimating actual endurance strength?

0.70 Signup and view all the answers

Which formula is applicable to cast iron columns?

Straight line formula Signup and view all the answers

Which ferrous metal has the lowest carbon content?

Wrought iron Signup and view all the answers

Which of the following materials is the most economical choice if stiffness is the main criterion?

SAE 1020 Signup and view all the answers

Which material is known for being easily machinable?

AISI C1112 Signup and view all the answers

What describes the mechanical properties of wood?

Orthotropic Signup and view all the answers

What is the term for the circle on a gear that corresponds to the contact surface of the friction wheel?

Pitch Circle Signup and view all the answers

Which of the following compositions represents stainless steel 302?

18% chromium and 8% nickel Signup and view all the answers

What is the function of a guide bearing in machinery?

It primarily guides motion without regard to load direction. Signup and view all the answers

What is the term used for the space between adjacent coils when a spring is compressed?

Coil clearance Signup and view all the answers

Which of the following best describes shot blasting?

A technique that shapes materials using a high-velocity stream of balls. Signup and view all the answers

What is the purpose of elastohydrodynamic lubrication?

To separate non-conformal surfaces completely using a lubricant film. Signup and view all the answers

Which machining process produces residual compressive stress by applying hammer blows?

Shot peening Signup and view all the answers

In the context of lathe machines, what does the term 'swing' refer to?

The diameter of the largest workpiece that can be rotated. Signup and view all the answers

What is the term for the mechanism that shapes stock while allowing excess material for finishing?

Drag-link mechanism Signup and view all the answers

Which material is known as Roughing, made primarily from cobalt, chromium, and tungsten?

Stellite Signup and view all the answers

What is the name for the load applied transversely to the longitudinal axis of a member?

Bending Load Signup and view all the answers

What is another term for the Maximum-Shear-Stress Theory?

Tresca yield criterion Signup and view all the answers

What does Miner's Rule state about cyclic and impact loading?

Damage at any stress level is proportional to the number of cycles. Signup and view all the answers

What is the name for a type of ball bearing featuring a pronounced groove in the race?

Conrad bearing Signup and view all the answers

What is the term for the algebraic difference between the size and the corresponding basic size?

Deviation Signup and view all the answers

What instrument is used for precise angular measurements and positioning with gage blocks?

Sine bar Signup and view all the answers

What is the typical dimensional difference for rivet holes compared to the nominal diameter of the rivet?

1/16 inch larger Signup and view all the answers

Which equation is specifically for thick-walled pressure cylinders?

Lame’s equation Signup and view all the answers

What G code command is used for dwell or rest in CNC programming?

G04 Signup and view all the answers

Which M code command is employed for a tool change in CNC programming?

M06 Signup and view all the answers

How does the true stress-strain curve compare to the engineering stress-strain curve?

Higher than the engineering curve Signup and view all the answers

What is the main hardening treatment used for low carbon content steels?

Case hardening Signup and view all the answers

What manufacturing process is primarily used for producing aluminum?

Extrusion Signup and view all the answers

What term describes the loss of material from metal surfaces that are in contact?

Fretting corrosion Signup and view all the answers

Study Notes

Thermal Expansion and Material Properties

Coefficient of thermal expansion quantifies how a material's size changes with temperature.
Chrome Vanadium is the preferred alloy for spring steel under high-stress conditions due to its fatigue resistance.
Stainless steel 302 contains 18% chromium and 8% nickel, enhancing corrosion resistance.

Mechanical Components and Definitions

Pitch Circle is the circle on a gear representing the contact surface with a friction wheel.
Guide bearings facilitate motion without regard to load direction.
Leaf springs consist of flat strips made from materials like brass and steel, acting as cantilevers.

Spring Mechanics and Lubrication

Coil clearance refers to the gap between compressed spring coils.
Elastohydrodynamic lubrication occurs when non-conformal surfaces are fully separated by a lubricant film.

Manufacturing and Surface Treatments

Shot blasting introduces residual compressive stress to machine parts through high-velocity pellets.
Peening uses hammer blows to produce surface compressive stress.
Nitriding is a surface-hardening process involving heating alloy steels in ammonia gas at 950°F.

Material Characteristics and Estimations

Endurance strength of alloy steels can improve by over 50% using nitriding.
The recommended material factor for cast steel in endurance calculations is 0.70.
Wrought iron has the lowest carbon content, typically under 0.04%.

Selection and Machinability

SAE 1020 is the most economical choice for stiffness among various steels.
AISI C1112 is a free-cutting steel that is easy to machine due to its higher sulfur content.

Wood and Fabrication Processes

Wood displays unique mechanical properties in three perpendicular directions: longitudinal, radial, and tangential.
Buffing improves the polish of metals, enhancing their luster.

Stress Relief and Materials

Stress relieving reduces internal stress through controlled heating below critical temperature.
Hot hardness denotes a steel's resistance to softening at elevated temperatures.

Cranes and Iron Types

A Jib crane features a supported vertical element with a swinging arm for hoisting.
Nodular cast iron is synonymous with ductile cast iron, indicating its enhanced strength.

Mechanics and Laws

Third law of motion states that a force acting on a body provokes an equal and opposite reaction.
Wrought steels are the most versatile and widely used engineering materials.

CNC Programming and Machining

G04 is the G code for dwell in CNC programming, while M06 indicates a tool change.
Fretting corrosion is the material loss at the contact interface of closely fitted metal surfaces.

Fits and Associated Terms

Shrink fit involves heating components to increase their inside diameter for assembly.
AFBMA refers to the Anti-Friction Bearing Manufacturers’ Association, focused on rolling element bearings.

Damage Theories and Specifications

Von Mises theory is known as octahedral shear-stress theory, predicting material failure under stress.
Miner's Rule states that damage proportionality relates to the number of cycles in cyclic loading situations.
A sine bar is a tool used for precise angular measurements, commonly paired with precision gauge blocks.

General Definitions

Code signifies a set of specifications aimed at safety and quality performance.
Deviation is the algebraic difference between a size and its corresponding basic size.
Standards ensure uniformity, efficiency, and specified quality in parts, materials, or processes.

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Description

Test your knowledge on key mechanical engineering concepts including coefficients of thermal expansion, gears, materials, and bearings. This quiz covers essential terminology and material properties relevant to mechanical design and engineering. Perfect for students and professionals seeking to refresh their understanding.