DML Final

Design Process Steps

1. Recognize Need 2. Define Problem 3. Gather Information 4. Concept Generation 5. Concept Selection 6. Communication of Design 7. Detail Design Stage8. Prototype Development

What step of the design process is the decision matrix used?

Step 5

What step of the design process corresponds with DR2?

Step 6

What 2 types of metal forming create near the net shape?

Casting and forging

What happens during extrusion?

Billet is formed in a long continuous bar

How is the grain structure aligned in extrusion?

Grain alignment with extrusion direction

2 Components used for extrusion

Piston and Die

3 Types of Casting

Sand, Investment, Die Casting

Rank types of casting from least expensive to most expensive

Sand, Investment, Die Casting

What types of casting requires post processing?

All casting types

What occurs in investment casting?

Wax mold in tree shape, coat in ceramic/sand, melt wax, use ceramic mold for metal

What type of casting uses a permanent mold?

Die casting

List components needed for sand or die casting

Sprue, Riser, cone

Catchphrase of forging

"Hit hot thing with hammer"

At what temperature does one forge a material?

Forging temperature (malleable but will not fall apart)

List strength of metal forming processes from weakest to strongest

casting, billet (extrusion), forging

How is the grain oriented in forging?

Grain "flows"

Does forging require post processing?

Yes

What are the steps to set up CAM for machining?

1. Set up (stock material, material for clamping, origin and orientation) 2. Tools (type, speeds&feeds) 3. Tool Path (how tool moves to cut material)

What is an interface?

A failure point

Why do we use tolerance tables?

To reduce clutter and establish standard for drawing

Can I dimension to a hidden line?

No

Minimum length of workpiece in lathe jaws

1 in

What is lathe turning? What axis?

Reducing the diameter, Z-axis

What is facing? What axis on lathe?

Reducing the length, x-axis

How long for roughing pass?

20 to 100 thou

Maximum cut for finishing pass?

20 thou

What moves in a mill? What stays stationary?

Tool stays stationary, workpiece moves

What axis goes toward the user in mil?

Y Axis

Criteria for sheetmetal?

Equal to or less than 1/4"

What is slug?

Part of sheetmetal that is punched out

What is it called when keeping the slug?

blanking

What is it called when the slug is discarded?

Punching

What is a Brake?

Name of tool for bending sheetmetal

Advantage/disadvantage of beam brake

easy to measure angle, hard to bend thick material accurately

Advantage/disadvantage of press brake

Hard to measure theta, easy to measure change in z

What does springback do?

Leads to theta being smaller

What is welding?

Process if fusing 2 or more pieces of similar metals through the use of heat and (sometimes) pressure

What does the addition of filler material in welding do?

Provides strength

Are welds permanent?

Yes

What is the difference between welding and brazing/soldering?

Brazing and soldering only melt the filler material (lower temps)

Rank welding, brazing and soldering from strongest to weakest

welding, brazing, soldering

Types of electronic arc welding and their nicknames

SMAW (Stick), GMAW (MIG)*lab, GTAW (TIG)

What is the cheapest type of welding?

SMAW

Advantages/Disadvantages of SMAW

cheapest, portable (no gas required), versatile; major post-weld cleanup, dirty (sparks/fumes), requires moderate skill

Advantages/Disadvantages of GMAW

fastest, easiest, versatile; requires shielding gas, minor post weld cleanup

Advantages/Disadvantages of GTAW

highest quality, no post weld cleanup, versatile; requires shielding gas, slowest, requires a lot of skill

Which welding process(es) use flux?

SMAW

What are the 3 categories of tools?

Milling/Turning, Hole making, Threading

What is milling for?

pocketing, profiling, facing

Which type of endmill is the best for profiling and fillets?

Ball Endmill

What type of endmill is the best for deep pockets?

Roughing endmill

Advantage of a ballmill

Can undercut with its relief

What is a reamer used for?

Finishing a pre-drilled hole

What is boring?

finishes pre-made holes by cutting around

What 2 tools are used to finish holes?

counterbore and countersink

4 categories of ways to cut things

thermal, erosion, mechanical, chemical

What is the highest precision cutting technique?

Electron Discharge Machining (EDM)

What are the 2 cutting mechanisms for lasers?

Melt&Blow (metals), Vaporization (wood,polymers)

Components of abrasive water jet

orifice, abrasive inlet, mixing tube

Parameters for cuttingdepth of cut (limited by stiffness), feed rate (limited by strength of cutting edge), spindle speed(limited by heat)

What is N in cutting speeds/feeds?

Spindle rotational speed (rpm)

What is V in cutting speeds/feeds?

surface speed (ft/min)

What is F in feeds/speeds?

Feed rate (in/min)

Units of fr

In (feed/rev)

Units of ft

in/tooth

What is m?

Number of teeth (edges)

Why are fasteners important?

#1 cause of premature failure

Purpose of fasteners

clamp 2 parts together

Common threaded fasteners

Nut&Bolt, screw, stud (threaded on both ends)

Typically the fastener diameter is equal to

the major diamater

Larger pitch coincides with which thread type

coarse

What are the failures of fasteners?

Tensile failure at root, stripped threads (shear)

What should be used to react shear forces?

Pin

On the top of a column of tap drill chart is what type of threading?

Coarse

If workpiece is softer than _ threads should be used

Coarse

How many tools does a bolt joint (bolt and nut) require to tighten or loosen?

2

How many tools does a screw joint require to tighten/loosen?

1

How many threads must be engaged during loading?

5

Advantages of rolled threads

superior surface finish (lower stress risers), improved material properties, higher fatigue resistance, and can be more economically to manufacture in larger quantities

What can be used to position parts relative to one another?

dowel pins, locating shoulders, piloting diameters

NEVER load fastener threads in

Shear

What keeps a properly designer fastener assembly tight?

Proper installation torque

The tool in a milling machine rotates about the machine's Z axis (T/F)

True

A tool in a lathe rotates about the machine's X-axis (T/F)

False, the tool does not rotate the workpiece does

Use of a tap

Create internal threads into workpiece

Use of tap handle

Holds tap so torque can be applied

Use of tap guide

(spring loaded) holds tap handle perpendicular to the workpiece

Use of endmill

Rotating cutting tool that can cut with its end (axially) or with its sides (radially)

Use of center drill

Short, stiff cutting tool used to accurately start a hole

Use of reamer

create extremely accurate holes in workpieces; used only as a final operation

Use of countersink

used to create conical holes in which countersink (flathead) screws can sit flush or slightly below the surface of the part

Explain any differences in geometry between a twist drill and an endmill

An endmill has a flat edge which a twist drill is pointed. An endmill is to face surfaces and a twist drill is used to create holes.

Before turning on a lathe, what are the 4 important things to check?

1. Range (speed) 2. Clearance 3. Chuck guard 4. Rotation Direction

The maximum depth of cut on a lathe is

0.1 in

When installing a workpiece in a vise, what are used to ensure the top surface is above the vise jaws and the workpiece is held flat?

parallels

5 steps before installing a tool into a milling machine

1. Machine is off &spindle not rotating 2. Plastic table cover below spindle 3. Release the quill clamp using palm of hand 4. Raise the spindle to upper-most position using quill handle 5. Raise spindle lock to highest position and thread it finger tight

What are the two things to check when installing a tool on the lathe?

tool height and cutting angle

What does MIG stand for?

Metal inert gas

What is the maximum increment in drill bit size you can make in a single operation?

0.25 in