Machining P20 vs P20+Ni | Milling Speeds, Tool Wear & Tips

P20+Ni hardness is higher (about HRC32–36), rotation speed drops to 150–220m/min, feed reduces 10–20%.

Choose to use coated hard alloy tools, maintain cooling liquid sufficient, layered cutting can reduce tool wear.

Milling Speeds

Carbide Tools

Processing carbon content 0.35% ordinary P20 steel material, towards formula inside mixing 10% cobalt, tool performance is very steady. Material particle size choosing 0.8 micrometers conventional powder, blade edge instantly bearing 600 Newtons impact force will not break. Meeting added 1% nickel element steel material, blade did not cut a few times edge then ground bald.

Workshop master will change on 0.5 micrometers ultra-fine particles pressed out alloy tool to deal with carrying toughness material. Tool outer surface that layer black gray color coating, thickness only has 2 to 4 micrometers. Titanium aluminum nitride coating under high temperature becomes one layer extremely thin aluminum oxide film. Ordinary P20 cut down iron chips temperature is about at 600 degrees, coating highest can carry hold 800 degrees high temperature.

One knife cutting into nickel-containing mold steel, contact point temperature within a few seconds soars to 850 degrees above. Old coating is instantly burned destroyed, must change to use aluminum content exceeding 50% aluminum titanium nitride coating milling cutter. New coating's anti-oxidation limit is pushed high to 900 degrees, surface micro hardness reaches 3800 Vickers hardness. Formula inside extra adds a little aluminum, one handful blade can cut full 3 hours, otherwise 20 minutes then scrapped.

Blade on those bumpy uneven angles are designed very rigid:

· Front angle is fixed at between 5 degrees to 8 degrees

· Blade rear angle's gap leaves sufficient 11 degrees to 13 degrees

· Edge uses brush ground blunt, radius exactly 0.015 millimeters

· Four chip flutes according to 35 degrees and 45 degrees stagger twisted

Front angle opened big, cut down iron chips along groove slide away. Nickel-containing steel material like nougat equally sticky, front angle smaller than 5 degrees, cut down debris will deadly weld on blade surface. Machine tool spindle rotation speed pulled to per minute 3000 revolutions, stuck on above iron lump is flung flying, incidentally tearing off 0.1 millimeters thick blade meat, blade edge all are fine small notches.

Machine operator hand inside always holding a 10 times magnifying glass, staring at tool tooth back surface looking. Wear band's width reaches 0.2 millimeters, no matter is just installed on or used half a day, must immediately change new tool. Taking a handful diameter 10 millimeters four-flute flat bottom cutter going scooping ordinary P20 steel block, can continuously walk tool 45 minutes. Scooping same size nickel-containing steel block, 28 minutes later tool then reached must throw away edge.

Roughing stage pursues per minute digging away 150 cubic centimeters steel meat. Masters use flying cutter disc, installed on four carrying R0.8 arc angle hard alloy blades forcefully downward cutting. Every time downward piercing 1.5 millimeters deep, cutter disc turning one circle every tooth forward gnawing 0.2 millimeters. Heavy gravity cutting time, machine tool screen on's load pointer in 65% to 75% between back and forth swinging.

High temperature under cooling technique decided tool can live how long:

· Absolutely cannot use water-based cutting fluid large flow rate flushing

· Open air valve blowing out 0.6 megapascals pressure cold wind

· Copper tube nozzle deadly aimed at blade eating tool's that point

· Put roasted into blue purple color curled iron chips rapidly blown running away

Just from 900 degrees fire sea inside coming out blade, by 25 degrees cold water one pouring, surface explodes open countless strips naked eye cannot see cracks. Using high pressure wind putting stuck in cutting area iron chips forcibly blown away, not letting blade going cutting early already cut off waste material, machine tool spindle's torque burden can reduce roughly 15%.

Finishing processing puts steel material surface scraped like mirror equally bright, roughness reaching Ra0.8 micrometers. Tool magazine inside changed on a root diameter 8 millimeters ball nose cutter. Spindle rotation speed booms to per minute 8000 revolutions, every time lightly scraping off surface 0.1 millimeters allowance. P20 surface left behind tool marks look very uniform.

Hard skin thickness almost 0.05 millimeters, hardness compared to bottom material high out 5 Rockwell hardness. Blade edge cutting into skin just like gnawing glass, extremely wasting tool. Old master puts per tooth feed amount forcibly pulled big to 0.08 millimeters, forcing tool tip one knife piercing through hard layer, going biting bottom slightly softer a little meat.

Tool holder clamping's runout has not close to human feeling (unreasonable) strict requirements. Holding dial indicator leaning on tool tip on turning one circle, pointer swinging amplitude cannot exceed 0.005 millimeters. Runout error extra out 0.01 millimeters, four tool teeth inside then has one forcibly carrying down 70% cutting resistance. Tool lifespan cliff style shortening, machine tool inside transmitting out screaming sound soaring to 95 decibels above.

In order not let tool cutting time with machine tool happening resonance, tool manufacturer puts chip flute's spiral angle made into not same. Four edges' angles staggered becoming 35 degrees, 38 degrees, 35 degrees, 38 degrees. Messy knocking frequency disrupted metal surface's vibration cycle. Downward digging 500 millimeters deep mold pit, side face's wave pattern depth successfully suppressed at 0.02 millimeters within.

Chip Color

Processing carbon content 0.35% ordinary P20 steel, iron rolls present out a kind very pure blue purple color. Blade edge per minute gnawing off roughly 150 cubic centimeters steel material, metal tearing instant produced nearly 650 degrees high temperature. About 80% heat is by iron chips taken away, tool tip actually bearing temperature exactly pressed in 400 degrees safe line inside.

Change on a piece mixed 1% nickel element P20+Ni mold steel, same spindle rotation speed running down, iron chips' color a few minutes within then will change face. High toughness material lets blade edge's cutting resistance increased almost 20%, friction brought out high temperature directly approaching 850 degrees.

Iron chips once turning black, hard alloy blade surface's that layer coating then only can again carry roughly 15 minutes.

Black color iron slag dropping on guide rail on, temperature exceeded 800 degrees, not careful splashing to hand back on can scald out water blisters. Machine operator hurriedly puts operation panel on's spindle rotation speed knob from 2500 revolutions dropping to 2000 revolutions. Feed speed also following from per minute 1200 millimeters retreating to 950 millimeters, machine tool inside that strand ear-piercing friction sound immediately sinking down.

Dropping speed after cut down iron chips anew returned to blue purple color, shape also from fine broken dregs became length roughly 30 millimeters C shape rolls. Chip flute inside's color just like thermometer's scale:

· Silver white bringing pale yellow: cutting area temperature insufficient 400 degrees, feed rate too low, blade edge on steel plate slipping scraping.

· Deep yellow brown to roasted blue: temperature controlled at 600 degrees to 700 degrees between, exhausting heat very healthy, blade can support full 3 hours.

· Pure black mixed with sparks: local temperature breaking through 900 degrees big gate, tool tip is currently happening thermal deformation softening.

Using diameter 12 millimeters milling cutter processing 30 HRC hardness mold steel, appearing large pieces silver white iron pieces, explaining per tooth feed amount possibly dropped to 0.05 millimeters below.

Processing surface on will leave down one layer 0.02 millimeters thick hardening layer, next knife again cutting in, tool tip just like touching 50 HRC quenched steel.

As long as iron chips curling arc maintains at radius 5 millimeters or so, outer layer flooding roasted blue color gloss, spindle load pointer steady at 65%, machine then can always opening. Cutting P20 steel material time, cutting fluid nozzle definitely must close off, change using 0.5 megapascals pressure compressed air aiming at spindle straight blowing.

Once opening cooling water, 650 degrees iron chips by 20 degrees cold water one pouring, instantly quenching becoming hard. Originally can smoothly exhausting into flute inside soft iron rolls, became hard banging broken steel pieces. These broken steel pieces once being rolled back tool tooth and mold steel's gap inside, 0.8 micrometers grain size hard alloy blade edge large probability will be chipped off yellow bean size one piece.

In workshop soaking ten several years old master, listening sound then can with iron chip color pair up number. Machine tool emitting uniform low deep "buzzing" sound, flying out iron chips basically all are beautiful blue purple color. Sound once becoming ear-piercing, mixed with metal tearing broken sound, lowering head one looking, ground on iron chips absolutely are one piece dead black.

Tool factory in order to control this pile waste iron's color, at milling cutter chip flute polishing on placed ruthless effort. Flute bottom roughness by grinding wheel forcibly polished to Ra0.2 micrometers below. Extremely smooth groove letting 850 degrees high temperature under sticky iron chips no way to stay on tool body on. Cutting into steel plate's 0.03 seconds within, iron chips then are forcibly curled then along flute flung flying going out.

Auditory Assistance

A handful brand new 10 millimeters hard alloy four-flute milling cutter just piercing into P20 mold steel, emitting is continuous and low deep "rustling" sound. Spindle rotation speed setting at per minute 2800 revolutions, eating tool depth 1.5 millimeters, taking decibel meter sticking on machine tool protective door on measuring, noise value firmly stopping at 75 decibels up and down.

Changing on containing nickel amount 1% 1.2738 mold steel, bottom noise immediately following changed face. Originally smooth cutting sound inside mixed in a strand extremely dull "buzzing" sound. Tool tooth biting into sticky material instant, spindle motor's load current from 12 amperes fiercely jumping to 15 amperes. Machine is gnawing toughness stronger metal meat, sound vibration frequency roughly lowered 200 Hertz.

Continuous processing 45 minutes after, coating surface being ground off roughly 2 micrometers, tool tip starting becoming blunt. Workshop booming sound inside occasionally will leak out several sounds extremely short "click" broken sound. One section 0.5 millimeters size broken iron chip did not able to along air flow fly going out, by blade second time rolling into bottom edge alive alive squeezed broken.

Machine operator putting different working conditions under cutting sound all recording in brain inside, forming one set flesh ear auscultation comparison table:

Using a handful protruding length reaching 50 millimeters slender rod milling cutter going scooping mold deep cavity, just contacting steel material side wall, 95 decibels high frequency howling sound instantly penetrating soundproof earplugs. Tool exactly with per second roughly 800 times frequency at extremely hard steel plate surface crazily bouncing scraping.

Old master putting hand inside multiplier knob towards left fiercely twisting half circle, spindle rotation speed from 3200 revolutions forcibly dropping to 2750 revolutions. Material surface physical excitation frequency is thoroughly disrupted, ear-piercing screaming sound disappearing, changing back slightly bringing dull normal cutting sound. Workpiece surface that path deep reaching 0.03 millimeters wave shape vibration pattern also following being smoothed flat.

Blade on's rear angle area wear band crossing 0.2 millimeters red line, tool body completely is forcibly squeezing steel plate. Tool tooth base's tungsten cobalt alloy fundamentally enduring not holding instantly soaring to 800 Newtons lateral pushing force.

Hearing bursting sound, leaving to operator slapping down red emergency stop button time not reaching 3 seconds. Late one second, four tool teeth will whole army wiped out, 50 bucks money one piece hard alloy blade carrying connecting value 300 bucks tool holder all will under 1500 revolutions rotation speed thoroughly twisting into waste iron.

Relying on hearing catching machine abnormal working conditions, comparing looking screen on's load numbers fast much more:

· Spindle belt slipping will emit slight "hissing" leaking wind sound, mostly happening at eating tool depth suddenly fiercely increasing to 2 millimeters cutting in instant.

· Blowing air nozzle spraying 0.5 megapascals compressed air sound if becoming dull, chip flute absolutely already by roasted blue iron slag blocking dead large half.

· Cutter disc cutting into blank edge emitting intermittent knocking sound, per second transmitting out roughly 4 times heavy hitting, feed multiplier needing forcibly pressing to 50% preventing crashing tool.

Nickel-containing steel material surface that layer 0.05 millimeters thick processing hardening layer, also is relying on ears catching coming out. Finishing processing using to R4 ball nose cutter walking curved surface, tool tip setting only eating 0.1 millimeters allowance. Just cutting into hardening layer, emitting sound like is a root fine steel wire on glass plate on deadly scraping.

Tool Wear Characteristics

Linear & Predictable

P20 steel material factory inspection certificate on finalized hardness deadly stuck at 28 to 32HRC between. Taking cutting machine cutting open looking metallography, inside tempered sorbite structure distributing like tofu equally even solid. This layer uniform iron base body inside scattering 1 to 3 micrometers size carbide hard particles.

Machine operator master putting panel on spindle rotation speed knob twisting to 8000 revolutions per minute. Tungsten steel milling cutter sticking iron block edge with 150 meters per minute linear speed gnawing in. Blade behind with workpiece friction strength from turning on machine to getting off work all maintaining at one precise number. Newly unsealed blade surface that layer titanium aluminum coating using thickness gauge hitting coming out exactly 3 to 4 micrometers.

· Head 5 minutes: blade behind punctually grinding out 0.05 millimeters wide bright strip trace

· 10th to 40th minute: per minute thunder striking not moving according to 0.002 millimeters speed towards up adding

· 45th minute: surface layer coating thoroughly grinding bare revealing inside gray color alloy bottom

· 50th minute: wear amount punctually crossing 0.3 millimeters changing tool warning red line

Just changing on new blade cutting down first knife, spindle motor load value firmly stopping at percent 15. Machine tool walking tool path slowly running enough 800 meters, load meter numbers then slowly crawling to percent 18. Hard pushing to 1200 meters walking tool limit, pointer firmly fixing at percent 22 position.

Operation table on feed multiplier knob turning on machine after then not by person touched, deadly locked in percent 100 scale slot inside. Spraying out iron chips color from just dropping knife time bright silver color slowly being roasted becoming withered yellow color. Temperature measuring gun hitting at cutting area, true temperature always being deadly pressed in 400 to 450 Celsius degrees safe cover inside.

Blade edge every gnawing off one cubic centimeter P20 iron block, it itself consuming away volume completely is fixed. Technician taking a 60 times magnifying measuring gap microscope aiming at tool tip recording down every time wear's millimeter number. Knocking keyboard putting one long string numbers one by one inputting into Fanuc controller tool management interface inside.

· Machine tool every operating 30 minutes system will automatically reading one time G41 tool compensation code

· Program putting tool wear deviation parameter towards negative number direction micro adjusting 0.02 millimeters

· Machine tool deadly biting parts drawing on requiring plus minus 0.01 millimeters dimension tolerance

· Setting tool lifespan countdown remaining percent 5 forcibly calling M06 changing tool command

Completely mastering tool can support how long, giving workshop scheduling shift scheduling production freeing out huge operation room. Night shift little brother towards circular disc tool magazine inside one breath stuffing in 10 handfuls same model four-flute end mill. System writing dead every tool fixed milling away 4,000,000 square millimeters workpiece surface area. Slapping down green cycle starting button, person patting butt going doing beside two machines' clamping.

Whole black light workshop night turning off lights can continuously doing full 8 hours not stopping machine. Workbench corner laser tool setter every interval 45 minutes punctually popping up conducting one time detection. Red probe touching one time tool tip, checking actual wear having not having crossing 0.15 millimeters finishing processing bottom line. Reading jumping out showing error only 0.05 millimeters, system immediately arranging blade continuing doing next one path process.

Brand new blade just getting on ground cutting coming out surface value stopping at Ra0.8 micrometers. Machine tool continuously running 1000 meters stopping down again measuring one time, screen reading quietly crawling to 1.2 micrometers. Waiting roughness value almost touching 1.6 micrometers drawing scrap line, pulling out tool taking caliper one measuring wear amount exactly is 0.25 millimeters.

· Just running to 1000 meters: cutting face presenting mirror reflection and remaining continuous fine dense tool marks

· Running to 1000 to 2000 meters: reflection starting becoming weak surface bringing little fog shape white spots

· Running to 2000 to 3000 meters: taking finger nail scratching past can picking to extremely micro steps

· Running exceeding 3000 meters above: surface starting hairing accompanying 0.1 millimeters deep vibration wave pattern

Several thousand meters walking tool time inside fundamentally meeting not sudden chipping edge breaking tool accident. Tool matrix inside densely packed tungsten carbide grains combating always is same one direction shearing stress. Eating tool line position actual cutting depth steady as Mount Tai piercing at 2.0 millimeters scale on. Touching not processing other complex steel materials time that kind local hardness suddenly soaring messy stall.

Guide rail lead screw bearing pulling force whole journey smooth steady, servo motor current chart hitting coming out just is one root big smooth curve. Spending big price buying returning coming imported hydraulic fixture continuously doing 3000 hours still can guard holding micrometer level positioning precision. Completing full set rough finishing processing scrapping away's merely is unit price 35 bucks money ordinary coating blade.

Ni Improving Toughness

Steelmaking furnace inside towards P20 original steel liquid pouring in percent 0.9 to 1.2 nickel (Ni) element, coming out steel ingot exactly is P20+Ni. Factory inspection report's impact testing column inside, Charpy V shape notch impact work from ordinary version pitiful 20 Joules instantly shooting up to 35 Joules above. Metal stretching testing machine tearing breaking this piece steel material's elongation rate forcibly pulling high percent 3 to 5.

This strand formidable anti-pulling tearing ability reflecting in machine tool inside, cutting coming out iron chips appearance completely changed. Originally cutting ordinary steel block dropping down all are 5 to 8 millimeters long C shape broken dregs, falling into chip conveyor chassis clattering rattling sounding. Now along four-flute milling cutter chip flute drilling coming out all are one root root 50 to 100 millimeters long curled iron wires.

Continuously not breaking spring shape chips deadly winding on BT40 specification tool holder on, taking 0.5 megapascals high pressure water gun flushing all flushing not dropping. Nickel element naturally heat conductivity extremely poor, percent 80 cutting heat exhausting not going out, all suffocating on fingernail cover size hard alloy tool tip on.

Iron chips sticking on blade edge on tearing not breaking, forcibly putting cutting contact face's friction temperature from 450 Celsius degrees doing to 650 Celsius degrees above. Exceeding 600 Celsius degrees high temperature putting iron chips bottom layer roasting soft, like maltose equally pasting on blade rake face on. Spindle rotation speed maintaining at 8000 revolutions per minute, rake face on per second all are repeating several hundred times sticking and tearing violent actions.

Accumulating to 0.05 millimeters thick built-up edge very quickly supporting not holding several hundred kilograms cutting force. Built-up edge falling off instant forcibly tearing down surface 3 micrometers thick titanium aluminum coating. Technician holding 60 times magnifying glass going illuminating changing down waste blade, tool tip position originally smooth edge line on, astonishingly appearing one row deep shallow at 0.02 to 0.05 millimeters between micro chipping notches.

Machine tool operation panel on's load pointer again also no way like before that way steady at percent 22. Pointer following tool intermittent cutting bringing impact force, at percent 30 to 45 between back and forth crazily jumping.

· Every milling past 100 millimeters processing distance, blade edge bearing torque comparing cutting ordinary material high out whole 1.5 times

· Coating under exceeding 700 degrees cutting heat, anti-oxidation lifespan being chopped off percent 60

· Spindle motor output power's three-dimensional chart from smooth straight line becoming one row densely packed saw-teeth

Hard alloy blade on nickel-containing iron block on heavily squeezing scraping past, workpiece surface's metal grains happening severe plastic deformation. Originally only 32HRC hardness steel material surface layer 0.1 millimeters depth within, hardness value can in one thousandth second within extremely fast soaring to 45HRC even higher.

This layer temporarily becoming hard metal outer shell like one layer bulletproof vest covering on workpiece surface. Second handful taking over semi-finishing tungsten steel milling cutter according to set good 2.0 millimeters cutting depth biting in, blade edge exactly locating at this layer 45HRC hardening layer's boundary line on.

Tool side face originally should uniformly consuming area, by hardening layer alive alive carving out one strip V shape deep groove. This strip groove's depth often in short 15 minutes walking tool within then reaching fatal 0.5 millimeters. Workshop managing this kind phenomenon calling boundary wear, is gnawing high toughness material time extremely easily triggering breaking tool's root cause.

Operator wearing 3M soundproof earplugs also can detecting full enclosed machine tool interior's movement not right. Tool because of deep groove wear losing original structural rigidity, at rotation speed reaching 6000 revolutions time triggering violent high frequency chatter. Workshop inside originally 500 Hertz low deep milling sound, becoming exceeding 2000 Hertz extremely ear-piercing metal friction screaming.

Dry cutting state under from chip guard inside spraying out sparks also changed color. Normal cutting originally is 400 Celsius degrees or so dark red sparks. Coating falling off failing after cutting area friction heat losing control, iron chips burning spraying out exceeding 800 Celsius degrees bright white sparks.

According to originally written good Fanuc cutting program walking, tool lifespan report completely becoming rotten accounts. Originally planning can steady running full 50 minutes blade, now often running to 15 minutes then in advance scrapping stepping down. Taking old rules going sticking 0.3 millimeters flank face wear red line, making coming out mold surface roughness Ra value often exceeding standard to 2.5 micrometers above.

· Purchasing list on according to one week 80 pieces reporting going up tool consumables, three days half then by warehouse keeper issuing empty

· Roughing stage not handled good 0.1 millimeters hardening layer, letting subsequent finishing tool lifespan discounting half

· Worker having to putting G code inside's back eating tool amount parameter from 2.0 millimeters quietly changing to 1.2 millimeters

Parts three-dimensional dimension's jumping range becoming ghosts gods hard to predict (mysterious). Previous knife cutting coming out contour dimension still stuck in plus 0.01 millimeters tolerance band inside. Changing handful new tool walking exactly same path program, drawing on requiring fitting face dimension deviation surprisingly running to 0.03 millimeters.

Judging Tool Lifespan

Just installing on spindle new tool gnawing into 28HRC P20 steel block, flinging coming out C shape chips flooding bright silver white color. Waiting blade back surface titanium aluminum coating being ground off 0.05 millimeters, iron chips color will slowly being roasted becoming bringing little burnt yellow roasted blue color. If transparent viewing window on smashing coming iron chips all becoming dark purple color, cutting area temperature absolutely already soaring exceeding 600 degrees.

Rotation speed 8000 revolutions per minute machine tool eating full 2.0 millimeters cutting depth, normal state under emitting is 500 Hertz or so low deep buzzing sound. Once tool tip appearing 0.02 millimeters micro chipping edge, sound immediately mixing intermittent cracking bursting movement. Waiting cutting sound becoming exceeding 2000 Hertz ear-piercing screaming, tool side face early grinding out deep groove, resonance is currently destroying spindle bearing.

A handful brand new diameter 12 millimeters four-flute end mill just getting on ground, load pointer deadly nailing at percent 15 position. Tool in nickel-containing steel block inside forcibly running 45 minutes walking tool trajectory, flank face wear amount unknowingly crossing 0.2 millimeters. This time going glancing screen, spindle motor output load already slowly crawling to percent 28.

If load value not smoothly rising, but is at screen on back and forth crazily jumping, blade basically then almost handing over (finished).

· Load pointer at 30% to 45% between crazily jumping

· Z axis current chart every 10 seconds popping out wave peak

· Spindle torque inexplicably increasing 0.5 Newton meters

· Rotation speed at 7900 to 8000 revolutions between micro dropping speed

Taking flashlight hitting a side light illuminating one time just milled finishing mold surface, blade's remaining lifespan numbers all writing on iron block on. Cutting state good time, surface remaining eating tool patterns uniformly arranged, spacing accurately maintaining at 0.15 millimeters. Following hard alloy matrix inside tungsten carbide particles continuously falling off, smooth clean surface starting popping out scattered white spots. Waiting finger belly sticking on iron block on can feeling out obvious step feeling, surface roughness Ra value early already crossing 1.6 micrometers.

Three coordinate measuring machine giving out dimension deviation report can earlier catching almost going to scrap tool. Program writing dead leaving 0.5 millimeters allowance giving finishing processing, front 10 pieces workpieces measuring coming out all are perfect 0.51 millimeters. Reaching 15th iron block, measuring probe reading returning coming data becoming 0.54 millimeters. This extra coming out 0.03 millimeters error, all is tool supporting not holding hardening layer producing physical yielding causing.

Technology department putting workshop groping coming out data organizing into book, printing into tables pasting at every machine CNC control cabinet beside. Machine operator following quantitative indicators going sticking changing tool time point.

Hard alloy milling cutter and hardness 32HRC steel material dry grinding, cutting area popping coming out sparks originally are dark red color. If continuous cutting 20 minutes after, chip guard inside occasionally popping out one two grains bright white sparks. Rake face on local temperature instantly breaking through 800 Celsius degrees, coating defense line starting collapsing.

Waiting sparks connecting into one piece blinding white light, blade front end cutting edge basically by high temperature melting into round angle. Operator putting spindle stopping down, taking air gun blowing clean tool holder on broken dregs going feeling bottom four edges. Originally presenting 15 degrees sharp rear angle edge, feeling going up smooth round like a handful ground flat blunt tool. Measuring gap microscope under hitting light one looking, cutting edge distance tool tip 0.2 millimeters position astonishingly by burning out a pit depression.

Pro Tips for Machining P20 & P20+Ni

Tool Coating

Lathe starting, spindle rotation speed soaring to 6000 revolutions/minute. Knife edge gnawing into containing 1.2% nickel mold steel, contact point temperature instantly soaring exceeding 850 degrees. Not wearing "outer jacket" bare board hard alloy tool, at most supporting 15 minutes then will burning completely black brittle. Giving it covering on one layer 2 to 4 micrometers thick coating, surface hardness can forcibly pulling high to 3300 HV.

Temperature breaking through 800 degrees big gate time, coating surface will towards outside "seeping" out one layer dense aluminum oxide film. This layer micro film like anti-heat shield equally, putting 70% cutting heat blocking at outside. Bottom's hard alloy tool body then will not be roasted soft deforming.

Taking a handful 10 millimeters thick 4-flute carrying coating milling cutter getting on ground doing work, feed speed pushing to 1200 millimeters/minute. Continuously gnawing biting hardness 35 HRC mold steel 45 minutes, taking micrometer one sticking, tool tip wear even 0.02 millimeters all not reaching.

Making this kind extremely thin anti-heat shield, factory inside has two kinds completely different furnaces:

· CVD furnace roasting coming out coating has 15 micrometers thick

· Thousands degrees high temperature easily putting bottom tool material roasting brittle

· PVD furnace temperature controlled at 500 degrees up and down

· Steaming coming out coating thin to only 3 micrometers

· Tool edge exiting furnace after still maintaining razor equally sharp

Tool tip eating tool amount setting at 0.15 millimeters, planing coming out iron chips like paper piece equally thin. This kind coating surface slippery extremely, friction coefficient only 0.3. Iron chips along chip flute then sliding going out, a little not sticking tool.

Meeting car bumper that kind big block head mold, machine tool often continuously spinning 10 hours not resting. Conventional coating at 1000 degrees long time roasting under also will into pieces dropping dregs. Factory inside making out one kind called nano composite coating craft. They putting good several kinds materials like spreading pancake equally stacking several thousand layers.

Every layer dough cake thickness being pressed to 5 to 10 nanometers. Tool tip touching hard bone producing micro cracks time, crack penetrating outside 2 nanometers titanium layer, hitting on bottom film then will stopping. This kind thousand layer cake structure letting tool anti-bumping ability improving 40%.

Lathe master judging what time should changing tool, all relying on eyesight and hand on simple tools:

· Pulling out 50 times magnifying glass closing near looking tool tip

· Coating dropping skin place exceeding half sesame grain size

· Blade edge behind wear bright band exceeding 0.2 millimeters

· Cutting iron sound from sharp howling becoming dull roaring

· Flying coming out iron pieces becoming emitting purple emitting black coke color

Water-based cutting fluid one pouring going up, coating outside anti-heat film fundamentally coming not to growing out. One cold one hot alternating pulling tearing, 3 micrometers coating inside all are naked eye cannot see cracks. Not going out 5 minutes, coating just like old house wall skin equally into blocks downward dropping.

Cutting this kind hard steel must use 0.6 megapascals high pressure air gun fiercely blowing. High-end goods exiting factory before, still needing using 2000 mesh fine sand water grinding one time coating surface. Removing processing time leaving down small protrusions, surface roughness can pressing to 0.05 micrometers below.

Bottom hard alloy containing 11% cobalt element, toughness sufficient. One knife cutting into nickel-containing mold steel, base deadly biting outside super hard coating, anti-pulling tearing force exceeding 1000 megapascals. Cutting process inside every little physical parameter change all recording in CNC system inside.

Doing work time must staring at screen, anytime rewriting eating tool data:

· Just getting on new tool, cutting linear speed running 120 meters/minute

· Doing full 2 hours, speed meter towards back dialing 15%

· Walking to turning corner dead alley, feed speed dropping 30%

· Dropping tool angle controlled at tilting 2 to 3 degrees

Drawer inside one box imported blades selling 300 bucks, installing on machine tool doing work then must calculating detailed accounts. Computer background staring at it cutting finishing 1,000,000 cubic millimeters waste iron, calculating dropping how much blade edge. Report inside writing very clearly, coating thickness differing 0.5 micrometers, tool lifespan then short 40 hours.

Preventing Work Hardening

Containing 1.2% nickel P20+Ni mold steel putting on workbench on, factory leaving hardness clearly only 32 HRC. Novice master starting milling machine, in order to saving tool, putting eating tool amount adjusting very small. Blade edge on metal surface rubbing several circles, not cutting down how much iron chips. That piece area steel material surface hardness will in zero point several seconds within crazily soaring to 55 HRC above.

This layer hardening layer thin like one sheet A4 paper, thickness usually only 0.05 to 0.1 millimeters. Forming hardening layer after, bottom originally 32 degrees steel material just like wearing on one piece high carbon steel armor. Tool again wanting cutting in, tool edge will like hitting on stone equally crazily slipping, accompanying ear-piercing high frequency screaming sound.

"Machine tool load meter pointer instantly from 30% flinging to 85%, sparks popping out, a handful 200 bucks money four-flute hard alloy milling cutter on the spot chipping breaking three edges."

Giving tool setting enough big per tooth feed amount ten parts (very) useful. A handful 12 millimeters diameter milling cutter, every grain tool tooth biting down thickness must rigidly stipulating at 0.15 to 0.2 millimeters between. Blade edge must real really cutting into meat inside, putting waste material turning into having thickness iron rolls.

Drawing on requiring fine repairing 0.02 millimeters allowance, putting to 1.2738 steel material on purely is looking for trouble. Extremely thin cutting depth even tool tip rounding angle all covering not holding, purely is taking 800 degrees high temperature roasting metal surface. Leaving to last one knife finishing processing allowance, bottom line is 0.15 millimeters.

Climb milling is workshop inside rules. Tool tooth just contacting material that one instant, cutting thickness reaching maximum value, subsequently gradually becoming thin until exiting. Big piece chips will immediately taking away 75% cutting heat energy. If using conventional milling, blade edge will at processing surface sliding 0.5 millimeters then barely cutting in, hardening layer early already by this half millimeter friction squeezing coming out.

· Tool along 45 degrees angle spiral line smoothly cutting into metal

· Radial eating tool width controlled at milling cutter diameter 15% to 20%

· Cutting speed calibrating at 110 meters/minute absolute interval

· Strictly forbidding spindle at mold cavity turning corner place fixed point idling

Using portable 50 times microscope observing, as long as flank face wear bright band width touching 0.15 millimeters, must changing tool. Blunting dropping tool edge no longer is cutting breaking metal crystal lattice, but is relying on 1500 megapascals squeezing force downward pressing.

Writing program computer screen on, tool path planning deciding spindle lifespan. Meeting right angle turning corner place, eating tool angle will suddenly becoming big. Programming master will in CAM software inside putting rough processing completely changing into trochoidal milling. Tool drawing circles forward walking, no matter walking to where, biting into metal angle always stuck at 30 degrees within.

"Putting trochoidal step locked dead at 0.4 millimeters, one head piercing into hardening layer inside, flying coming out blue iron chips curling like spring equally uniform, spindle load deadly stopping at 45% one moving not moving."

Drilling 10 millimeters deep hole, twist drill bit downward walking 3 millimeters then must lifting up exhausting one time iron chips. Thousand ten thousands (Absolutely) cannot letting drill bit at hole bottom staying exceeding 0.5 seconds. Lifting tool height at least wanting 2 millimeters, letting high pressure air flow thoroughly blowing away hole bottom 600 degrees debris.

Big blade flying cutter disc at flattening big face time, blade R angle largely having learning (knowledge). Using 2 millimeters R angle round shape blade replacing sharp angle blade, cutting force will be dispersed to longer one section arc on. Local producing cutting high temperature being spread thin, cutting point below metal crystal lattice receiving squeezing stress less 40%.

Ten thousand one (In case) tool not matching good, surface already hard like piece iron plate. Don't thinking using old tool slowly putting hard skin grinding away. Putting feed speed knob twisting to 120%, forcibly breaking situation.

· Changing on coating hardness reaching up to 3300 HV brand new blade

· Spindle rotation speed forcibly pressing low 25%, reducing heat accumulating

· Feed amount enlarging 30%, forcing tool edge crossing 0.1 millimeters hard shell

· Putting hardening skin and bottom soft material continuous roots pulling up cutting away

Normal cutting sound at 80 decibels or so, low deep and having rules. As long as sound frequency becoming sharp, decibel numbers soaring to 100 above, surface absolutely already knotting hard skin. Pressing down emergency stop button, disassembling down workpiece hitting hardness tester, just now still is 32 HRC place absolutely passing 50 HRC.

Reworking one piece being work hardened mold steel cost high outrageously. Milling cutter doing not moving hard pits, only can moving to electrical discharge machine tool on using red copper electrode going discharging ablating. Originally 20 minutes then can using tool planing finishing cavity, using 15 amperes current little by little shocking, wanting in spark oil inside soaking full 5 hours.

High Pressure Air Blowing

Cutting 1.2738 mold steel time, tool tip temperature year round lying at 800 degrees up and down. Water liquid pouring going up instant, one clump white fog soaring rising. Originally can cutting 3 hours imported hard alloy blade, supporting not reaching 15 minutes then breaking into residues.

800 degrees blade edge touching 25 degrees cold water, 0.1 seconds within happening violent thermal expansion cold contraction. Coating interior crystal lattice enduring not holding up to 800 megapascals pulling tearing force, densely packed micro cracks along tool edge spreading. Workshop inside managing that calling thermal shock. Dealing with nickel-containing pre-hardened steel, must putting water pump closing dead, whole journey using high pressure air serving.

Machine tool beside air pressure meter pointer must firmly stopping at 0.6 megapascals position. One root 8 millimeters thick copper tube aiming at spindle, blowing coming out air flow flowing speed can reaching per second 50 meters. Flying coming out iron chips carrying 600 degrees residual temperature, still not having coming to matching (in time) dropping on workpiece surface, then by crazy wind blowing to 2 meters opening outside sheet metal guard cover on.

P20+Ni planing coming down iron pieces again hard again sticky. If staying on tool walking past path on, milling cutter turning one circle returning coming then will putting them anew rolling in. Taking going cutting soft iron chips still okay, hitting on hardness 45 HRC high temperature iron slag, blade edge will in 3 seconds within be chipped off one notch.

Spraying air nozzle position placing is a technical work. Having experience master will putting copper tube breaking into 30 degrees tilting angle, tube mouth leaving cutting point exactly 50 millimeters. Wind pressure completely concentrating in tool front chip flute inside. Iron chips along spiral flute towards up crawling, just one revealing head then by high pressure wind knife neatly uniformly cutting off blowing flying.

Surface black wholly AlTiN coating temper very weird. Temperature going not to 800 degrees, coating surface aluminum oxide anti-heat shield fundamentally growing not coming out. Cold water one pouring, chemical reaction on the spot stopping. Using air gun dry blowing, contrary can letting tool in most comfortable high temperature interval inside doing work. Cutting coming out flute face bright can reflecting out human shadow.

Factory inside air compressor normally nobody managing, gas storage tank below accumulated water can having two fingers deep. Air tube inside if bringing water drops, spraying to tool on no different from towards roasting red iron pot inside scattering salt. Thousand ten thousands micro water drops hitting on 800 degrees tool tip on, same will putting hard alloy exploding out several micrometers cracks.

Pipeline front end must adding installing carrying three levels filter element oil water separator.

· First level filter net blocking holding tube inside iron rust and impurities

· Second level centrifugal bucket putting 99% liquid state water flinging dry

· Third level 5 micrometers high polymer filter element adsorbing water vapor

· Machine tool end blowing coming out wind must is absolutely dry

Deep cavity mold most letting human headache, for example giving P20 steel block digging one 150 millimeters deep blind hole. Outside air gun no matter how blowing, air flow in hole inside hitting a circle again coming out, iron chips all blocking at bottom. Spindle on tool only can relying on center exiting air function continuing life. Air along spindle interior channel, one road running to tool tip end two small holes spraying coming out.

Reaching up to 70 bar air pressure from drill bit bottom towards outside fiercely blowing. Just cutting coming down broken iron dregs by air pillar pushing, along drill bit outer side spiral chip flute, one road with 20 meters/second speed crazily running to hole outside. Tool tip at hole bottom staying safely steadily, a little extra friction heat all keeping not holding.