Machining Processes and Barrel Tumbling Quiz

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Questions and Answers

What is the primary purpose of barrel tumbling?

To create uniform shapes in the workpiece

To remove fins, flashes, and scales from parts (correct)

To cut down surfaces using abrasives

To apply paint or plating

What is the effect of adding water or dilute acid solutions during barrel rolling?

It slows down the tumbling process

It prevents rust formation

It reduces the amount of abrasive needed

It enhances the cutting action of the abrasives (correct)

Which materials are commonly used as abrasives in barrel rolling?

Synthetic powders and polymers

Steel shavings and rubber granules

Organic materials and cornstarch

Sand, granite chips, and glass fragments (correct)

How is the barrel filled for effective barrel rolling?

Loaded approximately 40 to 60% full Signup and view all the answers

Which final step is essential after tumbling the parts?

To wash and dry the parts thoroughly Signup and view all the answers

What characteristic of abrasives is emphasized to ensure effective cutting during barrel rolling?

Abrasives should be sharp-edged to pass across the surfaces Signup and view all the answers

Which operation is NOT typically associated with barrel tumbling?

Introducing heat to mold parts Signup and view all the answers

What is the recommended cutting speed for P20 material when used in machining?

Medium to low speed Signup and view all the answers

Which machining operation is suitable for P30 material?

Turning Signup and view all the answers

What is the typical feed rate when machining P40 material?

High feed rate Signup and view all the answers

For machining P50 material, what cutting speed range is recommended?

Medium to high speed Signup and view all the answers

What characteristic should the rake angle be for machining P30 under favorable conditions?

High rake angle Signup and view all the answers

Which material is specifically noted for having shrinkage cavities that affects machining recommendations?

P50 Signup and view all the answers

What is a common challenge when machining steel castings with P40 materials?

Frequent tool wear Signup and view all the answers

What type of chips are formed at low feed rates when machining P20 material?

Long chips Signup and view all the answers

Which of the following materials is NOT specified for machining within the P40 category?

Aluminum Signup and view all the answers

In what scenario is a large rake angle used when machining P50 materials?

Under unfavorable conditions Signup and view all the answers

Which materials are suitable for cutting with high toughness?

Tempered steel Signup and view all the answers

What is the maximum hardness of grey cast iron that can be efficiently machined using turning, milling, and planing?

220 HB Signup and view all the answers

Which of the following materials is most suitable for machining with high cutting speeds?

Copper alloys Signup and view all the answers

Which type of iron is characterized by forming short chips during machining?

Malleable cast iron Signup and view all the answers

Which of the following is not considered an abrasive type material for machining?

Soft plywood Signup and view all the answers

Which machining process can be applied to soft grey cast iron?

Shaping Signup and view all the answers

Which of these materials is best suited for machining under unfavorable conditions?

Tempered steel Signup and view all the answers

For which materials would reaming be an inappropriate machining process?

Grey cast iron with hardness over 220 HB Signup and view all the answers

Which materials are known for their resistance to wear while being machined?

Ceramics Signup and view all the answers

Which of the following is not a characteristic of materials suitable for high feed rates?

High toughness Signup and view all the answers

What temperature range can super-alloys withstand without losing strength?

600 to 1100°C Signup and view all the answers

Which type of super-alloy is commonly used in manufacturing turbine disks for turbo-jet engines?

Ni-Based Signup and view all the answers

What is the primary role of Chromium (Cr) in super-alloys?

Aids in carbide formation and imparts corrosion resistance Signup and view all the answers

Which of the following is NOT a type of super-alloy mentioned?

Ti-Based Signup and view all the answers

In which major application area are super-alloys primarily utilized?

Aero-gas turbines and Nuclear Reactors Signup and view all the answers

What is the primary purpose of the electrostatic fluidised bed process in powder coating?

To ensure uniform application of powder over a surface. Signup and view all the answers

Which of the following operations would best describe the polishing process?

An operation focused on improving surface aesthetics and decrease roughness. Signup and view all the answers

What type of materials are typically used for polishing wheels?

Diamond and silicon carbide. Signup and view all the answers

How is the polishing operation typically classified?

Based on the level of surface finish required. Signup and view all the answers

What is a common limitation of polishing operations?

It may not completely remove deep scratches. Signup and view all the answers

What level of surface roughness can typically be achieved after a polishing operation?

0.1 to 0.5 micrometers. Signup and view all the answers

Does polishing improve machining accuracy?

Yes, by making surfaces smoother. Signup and view all the answers

What is the characteristic color designation for carbide tips intended for precision turning?

P01 Signup and view all the answers

What machining condition is associated with carbide tip designation P10?

High cutting speed and medium feed. Signup and view all the answers

What is the appropriate cutting speed range for P30 material during machining?

Low to medium Signup and view all the answers

Which of the following materials is most suitable for turning, precision turning and boring?

Very hard grey cast iron Signup and view all the answers

For which machining operation is P40 material most effectively utilized?

Automatic machining Signup and view all the answers

What defines the toughness characteristic in materials used with a P20 classification?

Ability to withstand stress without breaking Signup and view all the answers

Which of the following abrasives is least likely to be used in barrel rolling?

Diamond dust Signup and view all the answers

Which material would you typically expect to have the highest hardness rating at 60 HRC?

Chilled cast iron Signup and view all the answers

In barrel rolling, what is the typical fill percentage of the barrel for optimal operation?

40% to 60% Signup and view all the answers

Which statement about the tumbling process is incorrect?

Tumbling should only be done with identical shapes. Signup and view all the answers

What distinguishes barrel rolling from barrel tumbling?

The focus on cutting rather than cleaning Signup and view all the answers

Why is wet rolling generally preferred in barrel rolling processes?

It results in a faster cutting action. Signup and view all the answers

After completing the tumbling process, what is an essential step for the treated parts?

Oiling to prevent rust formation Signup and view all the answers

Which abrasive paste is typically used for achieving a high-quality finish in polishing operations?

Aluminum oxide Signup and view all the answers

During which polishing operation is a fine grain size of abrasive typically used?

Finishing Signup and view all the answers

What is the typical surface roughness range achievable through polishing?

0.032-0.012 μm Ra Signup and view all the answers

Which of the following is NOT a typical material used for polishing wheels?

Plastic Signup and view all the answers

What material is often used in the polishing pastes alongside abrasives to enhance the finish?

Tallow Signup and view all the answers

Which polishing operation is primarily characterized by the use of dry wheels?

Roughing Signup and view all the answers

What type of parts poses challenges during the polishing process due to their geometry?

Irregular shapes Signup and view all the answers

What grain size range is associated with dry fining polishing operations?

90 to 120 Signup and view all the answers

What distinguishes polishing from lapping in terms of machining accuracy?

Lapping does not improve accuracy Signup and view all the answers

What is a key aspect of the mechanism involved in the polishing process?

Simultaneous action of the tool and paste Signup and view all the answers

What is the primary benefit of the burnishing process on a surface?

It enhances surface finish and induces compressive residual stresses. Signup and view all the answers

Which of the following describes the action of barrel burnishing?

Uses peening and rubbing to spread surface irregularities. Signup and view all the answers

What is typically NOT a characteristic of surfaces that have undergone burnishing?

The removal of visible pits and scratches. Signup and view all the answers

How should parts be prepared before barrel burnishing to ensure optimal results?

They should be rolled with a fine abrasive first. Signup and view all the answers

During the burnishing process, which of the following tools is commonly NOT used?

A milling cutter for shaping. Signup and view all the answers

What is one major disadvantage of burnishing in relation to surface defects?

It may not significantly smooth out deep scratches or pits. Signup and view all the answers

What is a key aspect of the operating conditions for effective barrel burnishing?

A specific volume ratio of shots to workpieces is crucial. Signup and view all the answers

What type of deformation is primarily associated with burnishing?

Cold surface plastic deformation. Signup and view all the answers

What is the relationship between barrel burnishing and surface porosity?

Barrel burnishing reduces surface porosity. Signup and view all the answers

What is the primary mechanism for maintaining workpieces during barrel burnishing?

Controlling the speed of rotation of the barrel Signup and view all the answers

Which method increases the wear resistance of burnished surfaces by 1.5 to 2 times?

Barrel burnishing Signup and view all the answers

What is a common application of roller burnishing?

Processing hydraulic system components Signup and view all the answers

How does burnishing pressure typically affect machining accuracy?

Reduces machining accuracy with increased pressure Signup and view all the answers

What materials can be effectively used in barrel burnishing processes?

Various sizes and shapes of shot material Signup and view all the answers

What is the effect of using smooth balls or mandrels in internal surface burnishing?

Raises the hardness of the surface significantly Signup and view all the answers

What is the process of powder coating primarily characterized by?

Spreading pulverized plastic powder followed by heat treatment Signup and view all the answers

What challenges might arise from fastening parts in racks inside the barrel during burnishing?

Possibility of uneven surface treatment Signup and view all the answers

What role do rollers and balls play in the roller/ball burnishing process?

Act as abrasive agents to smoothen surfaces Signup and view all the answers

Which materials are commonly used for powder coating apart from thermo-plastic resins?

Nylon, PVC, and thermo-plastic polyester Signup and view all the answers

Study Notes

Surface Finishing Processes

Tumbling is an inexpensive cleaning method using various shapes of slug materials in a barrel. It's often done dry, but can also be wet.
Tumbling is used for removing fins, flashes, and scales; cleaning forgings, stampings, and castings; deburring; improving micrometer finishes; finishing high-precision work to a high lustre; forming uniform radii; finishing gears and threaded parts without damage; removing paint or plating.
After tumbling, thorough washing and drying (using sawdust or infrared lamps) is necessary, followed by oiling to prevent rust.
Barrel rolling is similar to tumbling but used for cutting surfaces rather than cleaning. It uses abrasives (slag, cinders, sharp sand, etc.) in a barrel, loaded about 40-60% full.
Rolling is done wet or dry (sometimes with sawdust).
Rolling time varies from 10 minutes (non-ferrous) to 3 hours (steel). Results in a remarkably uniform surface.
Tumbling may be employed for removing fins, cleaning, deburring, and improving micrometer finish (among other applications).

Super-Finishing

Super-finishing is a micro-finishing process for controlled surface conditions.
It's also called 'micro-stoning'. Involves scrubbing a stone against a surface to produce a fine metal finish.
The process removes chatter marks and fragmented metal.
Effective for metal removal of 0.03-0.05 mm, and most economical when the removal is limited to 0.005 mm.
Rapid reciprocating a fine grit stone against a revolving work-piece, flooded with a cutting fluid.
Parts can be finished to a smoothness of 0.075 µm in 15-50 seconds but 2-3 minutes may be required for better finish.
The process is used for parts like computer memory drums, sewing machine parts, automotive cylinders, brake drums, bearings, pistons, piston rods, pins, axles, shafts, clutch plates, and tappet bodies, guide pins.

Burnishing

Burnishing creates a smooth and shiny surface through contact and rubbing against a hard tool (punch/die, rollers, balls).
It's a cold surface plastic deformation process, enhancing surface finish and fatigue life due to compressive residual stresses.
Barrel burnishing is similar to barrel rolling, but uses slug material for peening and rubbing. Usually done wet with a lubricant.
Roller/ball burnishing shapes (flat, cylinder, or conical) are burnished by hardened steel or carbide rollers/balls.
Results in a smoother surface (by 20–50%) and increased wear resistance (by 1.5–2 times).

Powder Coating

Powder coating involves spreading a pulverised plastic powder over the surface, then heating to fuse into a uniform coating.
It uses thermo-plastic and thermo-setting resins (nylon, PVC, polyester, epoxy).
Fluidized bed technique used for thermo-plastic resins.
Immersion of heated part in a fluidized powder bed.
Baking temperatures for epoxy resins range from 120°C to 135°C, with 20–30 minutes baking time.
Used for thick coatings, as well as decorative coatings.

Polishing

Polishing aims for a smooth and lustrous surface.
It uses polishing wheels (felt, cloth, wood, etc.) coated with abrasive (like Al2O3 or diamond) paste or fluid carrying abrasives.
Results in a surface roughness of 0.032-0.012 μm Ra.
Unlike lapping, polishing doesn't improve machining accuracy.
Polishing is categorized into roughing, dry fining, and finish polishing phases, based on grain size of the abrasive and lubricant use (roughing ranges from 20-80; dry fining from 90-120; and finish using fine grain sizes—150—with oil, tallow, or beeswax).

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Description

Test your knowledge on the principles of barrel tumbling and the machining of various materials. This quiz covers topics such as abrasive materials, cutting speeds, and specific characteristics of machining operations. Perfect for students and professionals in manufacturing and engineering fields.