Intro To Manufacturing Part 5

be able to label parts of the cutting tool

ex. size, shank, base, face, tool point, cutting edge, nose, flank

wear on the refielf face of the tool

wear on the rake face

transfer of atoms across the interface between the workpiece and the cutting tool

aslo known as attrition, occurs when 2 surfaces are brought together under high pressure and high temp

considered to be a catastrophic failure that occurs when a small piece breaks away from the cutting edges of the tool

(BUE) consisting of material from the workpiece, may collect on the cutting edges of the tool

single groove formation that occurs simultaneously on the face and flank of the tool at the depth of the cut

appears as hairline cracks perpendicular to the cutting edge

typically forms a bulge in the flank area of the tool

period of the cutting time that the tool can be used

equation for the estimation of the tool life, Taylor's tool life eqaution

V= cutting speed, ft/min (m/min)

T= tool life, min

n and C are the parameters that depend on factors such as feed rate, depth of cut, material, etc

high-speed steels

cast cobalt alloys

carbides

coated carbides

ceramics

cubic boron nitride

diamond

(HSS) most highly alloyed of tool steels,

used for drills, taps, broaches, and milling cutters

composition of 38-53% Cobalt 30-33% Chromium 10-20% Tungsten

-used for very large tools as opposed to solid carbide.

High hot hardnessHigh elastic modulus for toughnessGood thermal conductivityLow thermal expansion

Coatings are typically used to increase wear resistance

coated carbide inserts have increased machining rates up to 5 or more times over rates of uncoated carbides

usually used to machine cast irons and steels

lower cutting speeds and for machining super alloys

common ceramic cutting tools include

Silicon Nitride

Aluminum Oxide mixed with ZrO2, TiC, orTiCN

Aluminum Oxide mixed with Silicon Carbide whiskers

SiAlOH-solid solution of Al2 O3 in Si3 N4

have sharp cutting edges, provide excellent surface finished, have wear resistance of 20 times higher than uncoated carbides

Used for materials that produce a ductile chip- steels and ductile irons

Can machine carbon, stainless steels, and ductile irons at high speeds while producing excellent surface finishes

Work best in dry cutting applications

Not recommended for rough machines

One of the hardest materials available

Micro sized diamonds crystals in a carbide substrate compacted together under high pressure and temperature

Key parameter is shape

The geometry of the insert dictates the parameters of cutting

High rake angle-better for rougher cuts

Inserts size is determined by the largest circle that can be inscribed within its perimeter

Involves key factors

Cutting physics and economics

Goal is to choose a cutting tool shape, and material that minimizes cutting time, tool changes, tool cost, and setups while maximizing tool life, accuracy, and surface finish

Used extensively in cutting operations to reduce costs and enhance work piece characteristics

Straight cutting oils

Emulsifiable oils

Chemical fluids

Gaseous products

use of lathes and turning machines

Engine lathes, turret lathes, and NC/CNC turning machines

Engine Lathes-used for low-volume manufacturing runs

Bed- heavy metal casting supporting working parts of the lathe

Headstock- housing for the headstock spindle-which is a hollow shaft supported by bearings that holds the work holding device (3 jaw chuck)

Tailstock- support for straight and taper turning, drilling, and tapping

Carriage- provides the longitudinal movement of the cutting tool along the bed

Quick-change gear box- used for feeding-connects spindle to the carriage

Provides uniform feed rates

Produces holes by the relative motion of a rotating cutting tool and the work piece

Machine types include vertical, multiple spindle (gang), radial, and turre

*see notes for other info about drill, sizes, types, etc

Counter drilling- enlarges existing holes

Step drilling- when a hole with two or more diameters is cut with the same drill

Counter boring- enlarging a hole to a specific depth

Counter sinking- produces angular openings at the end of a hole

Reaming- used to produce accurate hole (size and roundness) with good surface finish

Center drilling- used to produce a tapered hole at the end of the work piece to accommodate a center in the tailstock or headstock or a lathe. Also used for accurately marking the location of a hole to prevent a twist drill from wandering

Size of drill designates the nominal diameter of its body and hole it is intended to produce

Standard drills are available in numbered, lettered, and fractional inch and millimeter sizes

Fractional sizes come in 1/64th inch steps up to 1 ¾” and larger steps above that to over 3”

Number and letter drills range from .0059-.4130 in. in diameter between the fractional sizes

common type of cutting tool

Machining process for removing material by relative motion between a work piece and rotating cutter having multiple cutting edges

standard vertical or horizontal knee-and column

computer numerical control CNC

machining centers

Slab milling

Face milling

End milling

Conventional/up milling- cutter is opposed by the feed of the work piece

Require more feeding force, generates higher cutting temps, produces rougher finish, tens to life work piece out of the vise or fixture

Climb/down milling

Pulls work piece a long, reduces feeding forceLower cutting temp, longer tool life, smoother finish

Using a long endless band with many small teeth traveling over two or more wheels in one direction

Three major types of tooth geometries

Standard

Hook tooth

Skip tooth

number of teeth per inch

Determined by the thickness of the material

Optimum pitch is ensured if at least 6 teeth are in contact with the same work piece at all times during sawing

Too few teeth- cause teeth to be stripped

Too many teeth- cause gullets to clog and results in rubbing instead of cutting

projection of the teeth from the sides of the band to provide cutting clearance

Raker set

Wave set

Straight (alternate) set

*see notes for materials used

Process used when high surface finish and high dimensional accuracy are needed

Time consuming and expensive, used when chip doesn't work for harder materials

horizontal or vertical spindle with either a traverse or rotary table

both internal or external

Abrasive type

Grain size

Bon

Grade

Structure

Faster metal removal rates by running high spindle speeds and feed rates but taking lighter cuts

1. Speed and productivity

2. Better surface finish to eliminate or reduce the need for polishing

basic spindle speeds of 10,000 rpm, 400 in/min or greater feed rates, and 2-5 axis machine control

accelerate or decelerate the tool for more effective cutting

Post processor- translates output from tool path software to specific machine codes

Operator- responsible for establishing valid base parameters, tool selection, and then running them

Precision machining process for generating internal cylindrical forms by removing metal with a single-point tools with multiple cutting edges

Traditional machining process used for special surface machining applications

set of cutting teeth that have cutting teeth at different heights to progressively remove material from the surface

2 types

Internal broaches- finish all or part of internal surfaces, keyways, or splines

External broaches- machine-in specialized features or contours on the work pieces external surface

Threads may be cut with single point tools on a lathe, or with multiple-tooth cutters that include taps, dies, and milling cutters

DIE- used for external threads

Tap- shank with several radically placed cutting teeth used to thread holes

Can be operated by machine or by hand

used when conventional methods are incapable, impractical, or uneconomical because of special material properties, work piece, complexities, or lack of inherent rigidity

removes material and procedures a narrow kerf by cutting action of a fine, high-pressure, high velocity, stream of water or water based fluid with additives

contains abrasive particles such as aluminum oxide or silicon carbide

widely employed method of removing metal without the use of mechanical or thermal energy

based upon the erosion effect of electrical sparks occurring between two electrodes

used in many applications such as drilling, cutting, heat treating, scribing, and welding.

Any metal forming operation done above the metal’s recrystallization temperature

Any metal forming operation done below the metal’s recrystallization temperature.

Cross between hot forming and cold forming, less heating than Hot Forming, less energy than Cold Forming

Highly productive, continuous forming process that can be done hot or cold.

Immersing the steel in a bath typically containing hydrochloric acid and inhibiters to prevent the acid from eroding the steel underneath

Cold rolling process for producing threads on cylindrical or conical work pieces.

Plastic deformation process in which material is forced under pressure through one or more die orifices

Billet form loaded into a thick-walled chamber, and pushed through a stationary die to form desired shape

Billet remains stationary, relative to the container wall while the die is pushed into the billet.

Hydraulic fluid is used in the ram cavity and, when pressurized, force is exerted not only to push the material through the die, but also away from the walls of the cavity.

Controlled plastic deformation or working of metals into pre-determined shapes by means of pressure or impact blows, or a combination of the two.

Simple shapes & rings, rings on discs of shafts

Work piece is placed between two dies containing the impression of the shape to be forged

does not depend on flash to fill out part

Produces fine details of parts in both top and bottom surfaces.

Increasing the diameter of a round work piece by decreasing its length

reduces cross-sectional area of a wire or bar by pulling it through a die

Uses hydrostatic pressure to move the work piece material so it will conform to the shape of a metal die.

Explosive forming: done with low and high explosives and gas mixes

Electrohydraulic forming

Electromagnetic forming

Process of mechanically cutting sheet metal with application of shear force.

Sheared slug is discarded, also known as piercing

ex. holes

Sheared slug is saved, remainder is scrap

ex. cookies

Involves removing metal from edges of ports

Similar to punching, but only around perimeter of part

Combines cutting and forming in one step.

Creates hole without completely separating the material

Produces very smooth and square edges

Punches out a series of overlapping holes to produce an elongated slot

Used for materials lie soft metals, leather, paper, and rubber, which are difficult to cut with conventional shearing.

Similar to cookie-cutter and cuts material into wood block.

Capability of a material to resist shearing.

Directly proportional to its hardness and tensile strength.

Clearance between the punch and the die is important. Too much clearance causes plastic deformation before it is out.

Made to gain rigidity and produce a part of a desired shape to perform a particular function.

Forming operation in which a narrow strip at the edge of the sheet is bent down along a straight or curved line

Creating a flange that has been bent 180º or more.

Curving material into cylinders or cylindrical segments.

Process of cold forming a flat pre-cut metal blank into a hollow vessel without wrinkling, thinning, or fracturing

Manual Presses: Hand or Foot- Operated through levers, screws or gears.

Mechanical Press: Utilize flywheel energy.

Hydraulic Press: Uses fluid power principles by means of pumps, valves, or intensities.

Specialized metal-forming process used for hollow products, that can be turned to produce desired shapes

a metal-working process for forming near-net shape, precision metal components, and shapes from metal powders

Powder manufacturing

Blending

Compacting

Sintering

Common method is called melt atomization

Oversize and fine particles are filtered out

Controlled amount of product is fed into a precision die

Develops metallurgic bands among powder particles.

Re-Pressing

Infiltrating w/ other metals, or impregnated with oils or resins.

process in which molten metal is poured or injected into a cavity and allowed to solidify, taking on the shape of the cavity.

misrun, cold shut, porosity, shrinkage, hot tear, core shift, and inclusions.

Upper half of the mold.

Lower half of the mold.

Used to create internal cavities in castings (Made of sand or metal).

Channel in which the metal enters the mold

Leads metal through the mold

Attach runner(s) to the mold cavity.

a reservoir connected to the mold cavity to feed liquid to the casting to prevent shrinkage as it solidifies.

A mold is compacted around a pattern with a sand-clay-water mixture.

multiple/single use

Higher degree of accuracy and surface finish than sand casting.

multiple/single use

Wax pattern is dipped into a ceramic slurry that hardens into a ceramic shell around that pattern.

single use

Process of casting, using expanded polystyrene foam patterns to eliminate the need for traditional mold cavities

single use

Pouring molten metal under pressure of gravity lead or a low-pressure feed system into a static mold.

multi-use

Molten metal is forced under pressure into metal molds or dies.

limited to 2000-4000 psi

Molten metal is located in separate holding furnace

means of joining materials by concentrating heat and or pressure at the joint to cause coalescence of the adjoining areas

parent materials and potentially a filler material melt together to form the welding joint

work pieces are joined by the application of heat and pressure or just by pressure.

Uses oxygen and acetylene to create heat to weld

Thermal cutting process that can cut straight or varying lines in steel (2 in thick or less)

Rapid burning or oxidation of iron in the presence of high-purify oxygen

Use of cutting tip

Electric arc creates heat through an consumable electrode that has a flux coating

Joining metal by arc between continuous wire and work piece

Direct current process

Amperage determined by wire feed speed

Joining metals by an arc between the work piece and a tungsten (non-consumable) electrode

Electrode is recessed as opposed to GTAW where it is extended from the tip

Can also be used as a cutting process for ferrous metals

Weld Splatter-Caused By:

Excessive welding current

Wrong electrode

Wrong electrode polarity

Too large an electrode

Improper electrode position

Arc blow

Excessive arc length

Low gas flow

Contaminated weld joint surfaces

High welding currents

Fast travel speeds

Improper electrode positions or manipulation

Excessive arc length

Too large of electrode

Improper current

Improper welding technique

Improper joint preparation

Wrong electrode size

Improper electrode manipulation of welding position

Porosity-surface holes, gas pockets

Incomplete cleaning

Long arc length

Moisture

Slag becomes trapped in weld resulting in weld failure

Caused by improper welding technique

Slow speed

Poor join prep

Residual stresses bend, etc.

Weld using resistance of welding current and pressure

Spot welding

Welding joint produced without melting the parent material or filler material

ultrasonic

friction

Laser-beam Welding

Electron Beam Welding

Thermit Welding

Weld bonding

Fusion joining process that produces coalescence of metals with heat generated by the absorption of a concentrated, coherent light beam.

Uses high-intensity beams of electrodes to melt the metals together

Produces weld with high depth to width ratio

Needs use of vacuum for production capacities

Can produce harmful radiation

Joining of metals by heating with a superheated molten metal produced by a reaction between a metal oxide and aluminum

Used for joining heavy and/or complex cross-sections not able to be welded by other welding processes

Common application welding rails for trains

Combination of resistance spot or seam welding and adhesive bonding

Improved fatigue life and durability

Provides corrosion resistance

Group of joining processes in which filler metal melts above 840 degrees F and below the melting temp of the metals being joined

Group of joining processes using a filler metal which melts below 840 degrees F and the metals being joined

Integral Fasteners

Formed areas of a component that function by interfering or interlocking with other areas of the assembly

Discrete Fasteners

Threaded fasteners including bolts, nuts, screws, and other fasteners such as rivets, pins and retaining rings

bolts, studs, nuts, screws, etc

Manufactured to close tolerances and designed for applications requiring high tensile strengths

Hardened fasteners generally used to hold pulleys, gears, and other components on shafts

Washer is placed on screw blank before threads are formed then becoming permanent part of assembly

Cut or formatting threads when driven into holes

Self-drilling, self-piercing, special tapping screws

Typically used on thin materials

Distance parallel to the axis from any point on a screw thread to a corresponding point on the next thread

Distance a screw has only one continuous thread on its surface (most common) lead=pitch

Diameter of a cylinder on which the crest of an external thread or the root of an internal thread lies

Diameter of a cylinder on which the root of an external thread or the crest of an internal thread lies

Diameter of a cylinder that cuts the threads where the width of the threads is equal to the width of the space between the threads

Creation of a standard form for threads

Unified screw thread form

Unified National Coarse (UNC)

Unified National Fine (UNF)

Unified National Extra Fine (UNEF)

American National Standard Taper Pipe Thread (NPT)

Each series specific the threads per inch (tpi) and basic dimensions and tolerances for cretin nominal inch size diameters

Thread class

Designates fit between internal and external mating threads

Metric thread designation begins with “m” following nominal size in mm after the times sign is the pitch

Unified National Coarse

Unified National Fine

Unified National Extra Fine

American National Standard Taper Pipe Thread

threads per inch

Provide simple and low cost method of mechanical fastening

Used extensively in the production of machines, tools, dies, and fixtures, to retain parts in fixed positions or preserve alignments

Used to position parts or transmit low torque forces

Made in slotted split tube and coiled designs

Advantages

Join dissimilar materials

Provide strong joints

Save weight

Reduce assembly cost

Distribute stress uniformity across the bon line

Significantly reducing the stress concentrations that cause fatigue and failure

Thin and fragile materials not suitable for mechanical fasteners or welding can be joined

Adhesives seal in addition to joining

Hard Deburring

Mass finishing

Tumbling and vibratory finishing

Abrasive Flow Machining

Semi-solid abrasive media is forced or extruded through a work piece passage

Thermal energy method

Used of intense and instantaneous heat to burn or oxidize burrs

Electrochemical Deburring

Use of electrochemical processes to remove burrs

Wire Brushing

Process used to achieve final sizing, correct contour errors, and provide desired surface finishes

Used primarily for burring operations

Abrasive machining process used for highly accurate stock removal under .001 in and five surface finishes

Cold working of a metal surface by a stream of spherical shot particles applied to a surface at high velocity under carefully controlled conditions

Used to enhance surface finish and appearance of a work piece

Work piece is made cathodic in a solution containing the ions of the metal being deposited

Forms a stable film or coating on a metals surface

Used for abrasion and water resistance

Liquid organic Coatings

Power Coating

Continuous operation that forces hot plasticized material through a die opening to produce the desired shape

general shape of the products they produce

Profile Extrusions

Pipe Extrusions

Sheet Extrusions

Film Extrusions

Filament Extrusion

Wire Coating

Process for shaping thermoplastic materials into one-piece, hollow articles by heat and air pressure

extrusion and injection(stronger for carbonated drinks)

ext=milk jugs

inj=soda bottles

Use of high pressure to deliver a material quantity of heated and plasticized material into a relatively cool mold which solidifies the plastics material

Heating plastic sheet or film to its processing temperature and forcing the hot, flexible material against the contours of a mold

vaccuum

Process for forming hollow plastic parts

Heated to plasticize material than are placed under pressure to form desired shape

like compression, but from one cavity to another