Buy P20 Steel for Molds | Block Size, Hardness, Processing Support

Purchasing time should confirm flaw detection grade (such as UT qualified) and uniformity, processing suggests adopting low speed cutting, feed 0.1-0.3mm/r, rough processing after reserve 1mm allowance then fine processing to guarantee dimension stable.

Block Size

Thickness

Steel plant inside's hot rolling machine presses steel plate, at most only can press to 130 millimeters to 150 millimeters thick. Steelmaking used's electric arc furnace one furnace loads 50 tons molten steel, poured out becomes 10 tons to 15 tons single block big steel ingot. Machine uses 3000 tons to 5000 tons' dead strength to press red-issuing steel material.

Encounter 200 millimeters above thickness's orders, all must be sent to forging workshop like kneading dough same hit. 8000 tons' hydraulic press facing 1150°C red-issuing rough steel block a bout of crazy smashing. Big mechanical hand grabbing several tons heavy material turns back and forth kneads 3 to 4 times. A piece final 500 millimeters thick material, has to back and forth hammer hit gather enough 4 to 1 deformation amount, inside's thick big particles then will break away.

Steel material made too thick, inside very easily hides not grown well small empty holes. Molten steel becomes cool becomes hard time will towards back shrink. 600 millimeters thick material, most middle often will deflate down leave a bit tiny seam. Quality inspector holding ultrasonic flaw detector facing steel material four sides sweeps, separated by thick thick iron skin catch blind see inside's defective points.

· 100 millimeters thickness within: take 4MHz high frequency probe, sound wave very easily penetrates.

· 100 to 300 millimeters thickness: according to SEP 1921 D/d grade standard little by little sweep.

· 300 to 500 millimeters thickness: steel slag particles become big block sound wave, change 2MHz probe.

· 500 millimeters above thickness: change 1MHz low frequency probe specially look for 10 millimeters big holes.

400 millimeters thick big iron block whole burns to 860°C, once enters oil pool, outside that layer 15 minutes within cools to 200°C below. Hidden in most exact middle position cools extremely slow, covered for fully 1 hour still has 600°C that hot.

Outside cools fast inside cools slow, one piece material cut open two kinds of temper. Away from skin 20 millimeters place cools fast, machine hits on tests out 34 HRC hardness. Towards inside deep dig to 200 millimeters exact center, slow swallow swallowly drop temperature lets material become soft. Rockwell hardness meter's pointer stops at 28 HRC scale on, up down differs quite a few degrees.

Take into workshop onto machine tool start doing, different thickness material want to scrape away skin also not same. 50 millimeters thick thin plate single face peel off 2 millimeters waste slag just can see bright face white meat. 300 millimeters thick material in fire inside burned ten-plus hours skin damaged severely. Except surface no carbon, top also crawls full 2.5 millimeters deep tiny cracks.

· 20 to 50 millimeters thin plate: up down two faces altogether scrape away 4 millimeters waste material.

· 60 to 150 millimeters medium plate: front reverse faces together peel away 6 millimeters then can use.

· 160 to 300 millimeters thick material: buy material time thickness has to extra leave 10 millimeters.

· 350 to 600 millimeters big material: single face peel skin 7.5 millimeters, totally extra leave 15 millimeters.

Use diameter 16 millimeters rough milling cutter probes into 400 millimeters thick steel bottom 250 millimeters deep place dig iron filings. Cutter arbor stretches too long easily shakes. Walk knife speed from one minute 1500 millimeters forcedly drops to 400 millimeters, machine tool inside issues out sound both sharp and ear-piercing.

One whole piece big material was dug empty 40% meat after, originally held in inside strength all ran out. A piece 1200 millimeters long, 250 millimeters thick board, naked eye looking all became bent. Put onto three coordinate instrument on hit meter one measure, middle position bulges up 0.8 to 1.2 millimeters, before peeled flat face all scrapped.

Want to remove this strand deformation strength, must take big iron block stuff into furnace inside slowly roast. Every hour only can raise temperature 50°C, fire too fierce surface easily explodes open. Furnace inside burns to 550°C to 600°C between starts countdown time. According to every 25 millimeters thick roast 1 hour calculate, 300 millimeters thick material must in fire furnace inside honestly wait 12 hours.

Roasted finished wait it cools through also is a spend time fine work. Closed electricity lets steel block follows furnace drop temperature to 200°C, must endure 15 to 20 hours. If rush to open furnace door blow 25°C room temperature wind, steel material one shrink, every 100 millimeters can short 0.05 millimeters, hard work drilled well hole positions all skewed.

· Steel plate according to per cubic centimeter 7.85 grams density calculates weight.

· 100 millimeters thick, 1 square meter big steel plate weighs 785 kilograms.

· 300 millimeters thick, 1 square meter big material weighs up to 2.355 tons.

· 500 millimeters thick, 1 square meter big big material fast approaches 4 tons.

Workshop overhead crane hoists so thick iron block, calculate wrong weight will produce big trouble. A piece 400 millimeters thick, 800 millimeters square material almost 2 tons heavy. Top on twisted inside's M16 lifting ring at most only can hang 1.2 tons. Fitter master has to at side face re-drill a 50 millimeters deep hole, change onto can carry 3.2 tons' M30 big lifting ring.

Machining Allowance

Black black hard skin thickness about at 1.5 millimeters to 3 millimeters up down. Hardness compared to inside good meat high out quite a few HRC, underneath hiding decarburization layer.

Open rough machine tool installs on diameter 63 millimeters flying cutter disc, rotate speed hits to 800 revolutions per minute to gnaw skin. Up down two faces peel away waste skin, single face has to eat knife 2.5 millimeters. Drawing on marked thickness 80 millimeters mold board, buy material thickness towards up add 5 millimeters is bottom line.

Thickness calculated finished, length width dimension reserved pit even deeper, cut material method says count. Take band saw machine cold cut, saw blade walks slow no sparks. A piece 41 millimeters wide bi-metal saw blade cuts over, walk knife gap eats away 2 millimeters material.

Encounter 500 millimeters long big block material, saw blade cuts to half will unavoidably happen 0.5 to 1 millimeters skew. Saw machine cuts length width single side extra leave 3 millimeters can guarantee bottom.

Acetylene mixed oxygen sprays out 3000°C high temperature flame, hard live live takes tens of centimeters thick steel plate burns through break open. Cut mouth two sides by fire roasted over area locally anneals, towards inside extends 8 to 12 millimeters.

This layer meat take file one scratch all drops dregs, bears not hold injection machine closing mold strength. Encounter flame cutting black skin material, length width direction single side at least towards out expands 15 millimeters. Finished product 400 times 400 millimeters board, use fire cut drop material must buy 430 times 430 millimeters square block.

A piece long 1 meter, wide 600 millimeters P20 pre-hardened board, put onto CNC dig away middle 30% material make mold frame.

Machine tool one stops, use dial indicator hit flat face towards up warps up 0.4 to 0.8 millimeters. Fitter takes board flips a face re-onto machine tool. Change onto diameter 25 millimeters fine milling cutter again walks one pass flat face.

Reserved allowance inside wraps hold this 0.8 millimeters leveling space. Old master calculates material, takes smooth knife's allowance accurately deducts to 0.15 millimeters. Left bit meat handed over to workshop inside surface grinding go finish up.

Large water grinding machine installs on 80 grit white corundum grinding wheel, one time down knife eats 0.01 millimeters. Back and forth hundreds times takes remainder ground away. Sparks carrying iron filings by cutting fluid flushed into water tank.

Board center digs pit makes cavity, side wall and bottom face same want to leave meat. Open rough cutting tool walks to away from drawing dimension still has 0.5 millimeters place stops retreats knife. Big material open finished rough thrown on workshop empty ground naturally placed 48 hours scatter strength.

Mold leave factory before does surface nitriding treatment, grows out a layer 0.05 millimeters thick white bright hardened layer. Dimension towards outside expands about 0.01 to 0.02 millimeters. Polishing master holding 400 number oil stone in cavity inside grinds consumes this bit remainder.

· Smooth board's purchase unit price one kilogram expensive out two three bucks money.

· Workshop saved away every day ten-plus hours listening to rough milling cutter scrape black skin's ear-piercing noise.

· 100 kilograms' rough material scraped away outer skin becomes 85 kilograms' net dimension board.

· Swept out 15 kilograms iron filings according to one catty few cents money sold to scrap station.

Pass two days moved onto machine tool takes remaining 0.5 millimeters allowance knife by knife finely scrape away. Inner diameter micrometer on numbers steadily stop inside tolerance 0.02 millimeters red line. Leaves exactly right dimension, drawing on model perfectly lands ground.

Dimension Effect

Bought back P20 mold steel length width as long as exceeds 500 millimeters, volume becomes big just will stir up cannot see trouble. A piece long 800 millimeters, wide 600 millimeters, thick 400 millimeters big steel block, total weight approaches 1.5 tons. Take it throw into quenching pool inside, even if outer surface already by cooling water washed to 50°C, its stomach inside real temperature still has 500°C.

Heat dissipates not out, steel block most center meat just will become soft. Surface take instrument hit a bit is 32 HRC standard hardness. CNC milling cutter towards inside deep digs 250 millimeters makes injection cavity, reached pit bottom again hit a bit hardness, value slides down to 26 HRC, fully dropped 6 Rockwell hardness units.

Fitter master takes rough file following deep pit bottom rubs two times, relying on hand feel just knows knife marks eat very deep, iron filings drop compared to outer layer fast much.

Pit bottom becomes soft after, polishing master takes 800 grit sandpaper however grind also grind not out bright face. Originally drawing requires reaching Ra 0.8 smoothness, due to material middle tissue loose, polished out surface all is circle by circle tiny orange peel ripples. Plastic injection machine uses 120 megapascals pressure takes melted glue hits inside, demolded out product surface all flowered.

Buy big dimension material before must calculate accurately hardness loss account book:

· Length width 400 millimeters within material: core part hardness at most drops 1 to 2 HRC.

· Length width 600 millimeters material: deep dig 200 millimeters after, hardness must drop 3 HRC above.

· Length width breaks 800 millimeters big guy: center hardness even 25 HRC all keep not hold.

· Hollowing out rate exceeds 50% deep barrel mold: bottom must additionally inlay 38 HRC high hardness beryllium copper block.

Onto CNC machine tool open rough, operator stares at screen on spindle load meter just can see out clues. Cut outer layer hard skin, spindle load stable at 65%. Cut to 300 millimeters deep exact center position, material becomes soft sticks knife, chips discharge extremely not smooth, machine load on the contrary soars to 85%.

A piece brand new R8 round nose cutter walks cutting feed, outer periphery can cut full 30 hours then wears out. Probes to gets soft deep pit inside go cut, soft spongy iron filings wrap on blade edge pull not broken, local cutting temperature soars to 600°C. At most support 15 hours, knife tip coating all collapsed.

Know business buyers encounter length width exceeds 600 millimeters orders, bill on absolutely not write ordinary P20, all change to added 1% nickel element's 1.2738 modified material.

Steelmaking furnace inside towards molten steel inside extra scatter about 1% to 1.2% nickel (Ni) metal powder, can forcedly change big block iron internal crystallization temper. Nickel can pull surrounding iron atoms, in temperature dropping extremely slow stuffy jar inside forcedly crystallize out dense hard tissue. Buy added nickel big block material, one kilogram wants extra spend two three bucks money.

Not willing spend money change material, hard take big dimension ordinary material make deep cavity mold, mold lifespan account calculates extremely ugly looking. Normal small material hits 300,000 mold times, parting face sharp angle intact undamaged. Big material center soft, hits to 150,000 mold times, deep cavity bottom exhaust groove just by high pressure plastic flushed collapsed 0.15 millimeters.

Injection machine closing mold force easily hundreds tons up to thousands tons. 1000 tons clamping force presses on a piece length width 700 millimeters, center gets soft mold board on. Slightly has force receiving uneven, internal soft collapsing position carries not hold huge squeezing, whole mold board middle position will sink down 0.05 to 0.08 millimeters.

Make mold must at four surroundings drill a circle transport water holes to cool drop temperature. Take diameter 10 millimeters deep hole gun drill from side face towards inside drill 600 millimeters long water path. Outer periphery material hard drill bit walks straight, drill to middle soft material area, force receiving uneven leads to drill bit runs skewed. Drilled through after take caliper one measure, exit position skewed fully 3 millimeters.

Encounter big guy material drill deep hole, workshop masters hands feet all must put slow:

· Drill speed from usual per minute 800 revolutions forcedly drops to 500 revolutions below.

· Cutting fluid pump pressure dead dead tops at 100 kilograms pressure, fiercely flushes soft iron filings.

· Every drill in 50 millimeters, machine tool forcedly retreats knife one time discharge slag discharge heat.

· Run into middle extremely soft area, manually takes feed presses to per minute 10 millimeters.

In case big mac mold made finished still not rest assured, sent to vacuum furnace inside again do one time surface nitriding add hard. Length width one meter big guy in 520°C furnace inside stuffy 48 hours. Take out cooled through installs machine, huge self weight plus inside outside hardness difference, mold slightly bumps a bit edge just collapses away broad bean big a piece iron.

Drawing on encounters deep dig 300 millimeters giant plastic water basin mold, designer simply takes bottom soft meat all hollows empty, separately makes a hardness 48 HRC quenching insert piece embeds inside.

Length width dimension every increases 100 millimeters, steel block stomach inside hidden variables multiplied somersault. Drawing on drawn is a perfect rectangular cuboid, machine tool cuts open after, outer shell is a set iron bones, deep place core however is a bag soft mud. Calculate accurately steel material volume becomes big brought hardness loss account, buy material then will not spend wronged money.

Hardness

Pre-hardening

Steel plant inside, a piece long 2 meters, wide 1.2 meters, thick 60 centimeters P20 steel plate just out furnace, weighs up to 11.3 tons. Overhead crane hoists this piece burned red hot iron lump, stuffs into 860 degrees heating furnace. Big fire fully roasted 18 hours. Inside iron atoms under high temperature all messed up sets, re-queue.

Just out furnace immediately throw into 3000 liters tumbling cooling pool inside. Outer layer iron skin temperature in 40 minutes within crazy drops to 150 degrees. But 60 centimeters thick heart pit really too thick, stubbornly spent 6 hours then cooled through. Hundreds megapascals pulling strength all held in iron block stomach inside.

Molten steel inside added 1.8% chromium and 0.2% molybdenum, helping cold air towards meat inside drill. Just scooped up iron block hard scaring people, Rockwell hardness soars to 50 degrees above. Immediately again hoist into beside 550 degrees furnace inside return furnace. Continuously baking 12 hours, originally brittle hard temper by slowly ground soft.

Leave factory hardness by dead dead fixed at 30 degrees around, also is everyone often says pre-hardening. Take big saw cut down 20 centimeters thick edge corner material. Take hardness gun hit a bit outer skin, shows 31 degrees. Probe towards center point approaches 30 centimeters again hit one gun, reading 28 degrees, inside outside differs not big.

Bought back 3 tons heavy iron block directly onto machine tool, not need again send go heat treatment plant toss. Machine tool installs on 63 millimeters diameter big flying cutter, top fastens 5 pieces alloy cutter grains. Master takes spindle rotate speed dials to per minute 1200 revolutions. Walk knife speed pulls full, per minute advances 1500 millimeters.

One knife down goes gnaws away 0.8 millimeters thick iron skin. Blue purple C shaped iron filings like raining same collapse onto surrounding baffle boards. Iron filings become blue, explains knife tip there instantly rubbed out 500 degrees high temperature. 30 degrees hardness exactly good, iron flowers receive force curl few circles just crisp cleanly collapsed broken.

Plant inside machine operation workers usually see fire condition's few tricks earth methods:

· Look iron filings color, deep blue bringing bit white edge exactly good.

· Touch leftover material, hand feel passes 50 degrees knife blade just almost not work.

· Look ammeter, empty rotate time current suddenly extra out 20 amperes immediately press stop.

· Take caliper measure step, differed 0.02 millimeters just is cutter arbor carries not hold bent.

Rough processing left 0.15 millimeters skin waits fine repair. Machine tool changes onto 8 millimeters thick ball head small cutter, rotate speed crazy soars to 8000 revolutions. Next 40 hours, all rely on it go hollow that car bumper complex concave pit.

30 degrees base bottom to small cutter extremely friendly. Knife tip runs up speed reaches per minute 180 meters. Computer programming sets every step only moves 0.05 millimeters. Concave pit surface scraped out knife marks neat neat tidy tidy, take hand one touch, with 150 grit rough sandpaper not differ much.

Mold down machine tool hands over to polishing worker. Master takes 400 grit grindstone dips on bit kerosene, following grain forcefully pushes. Leave factory before burned through material foundation solid. Grindstone every time scrapes out mark deep shallow exactly same, basically all at 0.01 millimeters deep.

Polishing table front every day circle not away's few pieces small broken things:

· 400 grit oil stone rubs 100 times, exactly grinds away 0.02 millimeters iron skin.

· Encounter 0.05 millimeters big hard lump, one drag just is a long tail.

· Change onto 1500 grit fine sandpaper rubs finished, 2 meters away words all can shine see.

Almost polish finished time, iron plate on suddenly pops out 0.05 millimeters deep pits and puddles, jargon called rise orange skin. Polishing master continuously endures 3 days night all white did, mold only has to drag back machine tool re-mill one pass.

Mold made well moves into injection plant, installs on 800 tons machine. 250 degrees melted into paste ABS plastic by thick screw rod dead life towards front pushes. 120 megapascals high pressure takes plastic paste hard stuffs into pit inside. Two pieces big iron plates every time crash together, all must carry hold 400 tons smashing force.

Performance & Lifespan

800 tons injection machine one day 24 hours continuously rotates. Every 45 seconds two pieces big iron plates just violently crash one time. 400 tons clamping force all presses on P20 mold that circle not reaching 20 millimeters wide edge seam on. One day down iron blocks solidly mutually smashed 1920 times.

Cannon barrel inside 260 degrees PC melted glue like mud rock flow same rushes into mold cavity. Enter glue port position bears brunt receives per square centimeter 1500 kilograms flushing force. High temperature paste-like plastic sticks on 30 degrees hardness steel wall on rubs.

Mold internal water pipes crazily pump away heat. 20 seconds within steel material outer skin temperature from 90 degrees by forcedly dragged back 45 degrees. Thermal expansion cold contraction drama in this tens of micrometers thick outer skin layer inside every day staged nearly two thousand times.

Endured to 150,000th mold, workshop master holds strong light flashlight shines towards enter glue port. Originally shiny can reflect people enter glue point surroundings popped out a small circle dark gray pockmarks. Take magnifying glass approach look, that is 0.015 millimeters deep tiny flushing pits.

Ordinary not added material PP or ABS plastic to P20 most polite. Plastic itself soft and melting point at 220 degrees around. Hit full 300,000 mold times take micrometer caliper a bit cavity depth. Wear amount still not reach 0.02 millimeters, assembled out home appliance outer shell dimensions one thread not differ.

Run into PC material lifespan just wants to discount. PC material viscosity extremely big, injection machine takes injection pressure pulls to 130 megapascals above. Hit to 250,000 molds time, draft angle only has 1 degree place just starts to issue condition.

Ejector pin forcedly takes astringent PC part tops out. Plastic part side wall and mold steel happen dry friction, drags out a 0.05 millimeters wide tiny pulled wire. Quality inspector touches plastic shell outer surface's slight scrape hand feel, mold just must down machine platform go maintain.

Ten million do not take go hit glass fiber. Some plants scheme save trouble use it hit containing 20% glass fiber PA66. Tiny glass fibers like countless pieces miniature files. Only hit not reaching 30,000 molds enter glue port just by gnawed away 0.12 millimeters, only can on spot scrap.

Old fitter deals with mold daily wear loss has own one set handicraft:

· Edge by pressed collapsed 0.03 millimeters, take argon arc welding machine dot on few drops welding wire again take file slowly grind flat.

· Ejector pin hole surroundings ground out 0.05 millimeters gap will leak glue, immediately change a root big one size ejector pin stuff inside.

· Enter glue port pockmarks exceed 0.02 millimeters deep, polishing worker wants to take 800 grit sandpaper re-rub two hours.

· Cooling water pipes inside scaled 2 millimeters thick water scale, heat dissipates not out mold temperature will rise 15 degrees, must pour acid wash liquid.

Mold put into 500 degrees sealed tank inside pass into ammonia gas roast 24 hours. Nitrogen atoms towards steel outer skin inside drill, seeps inside almost 0.15 millimeters deep.

This layer 0.15 millimeters skin hardness soars to 60 degrees above. Take big file rubs on directly slips even one path white mark all leave not down. Done nitriding cavity go hit ABS plastic, can hard live live carry to 500,000 mold times.

Nitriding layer very hard but also brittle like piece glass. Run into machine not adjusted well, two pieces iron plates clamped a 0.5 millimeters thick plastic debris. 400 tons strength presses down, that piece's nitrided hard skin instantly collapses away rice grain big one corner.

Collapsed mouth place exposes underneath 30 degrees hardness soft meat. High pressure melted glue following gap towards this small pit inside dead life drills. Repair up extremely spends effort, welding torch one burns surrounding hard skin all scrapped, must take angle grinder first scrape away 0.2 millimeters surface layer.

Plant inside statistics mold service real account book:

One set mold continuously hits 400,000 molds basically just reached retire age. Steel block not broken, but everywhere's dimensions all loosened collapsed. Guide pillar and guide sleeve between originally only had 0.01 millimeters gap, hard live live by ground to 0.08 millimeters.

Hit out plastic basin edge one side thick 2.1 millimeters, another side only 1.9 millimeters. Flying edges following became big gap towards out squeeze, aunties every day want to take scissors trim half day hairy edges.

Take whole parting face re-drop down 0.5 millimeters again onto milling machine process, machine tool fee plus labor wants to spend away big thousands bucks. Calculate account not as good as re-buy piece 11 tons heavy steel plate from beginning start hollow.

Uniformity

Bought back a piece long 1500 millimeters, wide 800 millimeters, thickness reaches 450 millimeters P20 steel ingot, weighbridge bill on writes 4.2 tons. Workshop master gets material first piece thing, absolutely not is immediately start crane onto machine tool, but picks up a piece heavy reaching 2 kilograms portable Leeb hardness tester.

Probe bringing tungsten carbide small ball, with per second 2 meters initial speed smashes towards steel block outer skin.

Screen on jumps out HL 530 reading, contrast hardness conversion table, outer skin hardness steadily stops at 30.5 HRC.

Operator picks up chalk, on 450 millimeters thick saw cut side face drew a nine-square grid. Every interval 100 millimeters hits one gun, data happens tiny jumping. Towards inside walks 100 millimeters, reading drops to 29 HRC.

Probe pokes to distance edge 225 millimeters deepest position, inferior quality material real face thoroughly exposed. Screen numbers flash, all the way crazy falls to HL 410, converts down even 22 HRC not reach. Outer skin and inner core drop approaches 9 HRC.

Plant inside old machine operator runs into inside outside soft hard not one material, always will encounter few trouble things:

· Spindle rotate speed set at 1500 revolutions, cut outer skin time machine tool load 50%, cut to inner core load instantly drops to 30%.

· Same style knife blade cuts 30 HRC can run 4 hours, runs into 22 HRC soft core extremely easily happens dead dead stick knife phenomenon.

· Dug out 300 millimeters deep cavity after, bottom surface roughness from beginning to end reaches not Ra 0.8 standard.

Machine tool right now with per minute 800 millimeters speed towards down hollows a deep cavity, prepares to make washing machine inner barrel mold. Cutter tool eat knife depth set as 0.5 millimeters. Knife blade just gnawed finished surface 30 HRC hard material, one head plunges into only has 22 HRC soft spongy inner core.

Originally crisp metallic cutting sound, few seconds within became muffled "pu-pu" sound, like a blunt knife cutting rotten meat.

Cutting area discharged iron filings color happened change, from normal deep blue became completely no luster silver white. 22 HRC soft material like nougat candy same sticks on chip discharge groove on. Worker stops machine tool, takes long handle iron hook go drag out that lump long reaching 30 centimeters iron wire ball.

Hardness drop too big, cutting produced heat completely not same. Cut outer skin time knife tip temperature 500 degrees, cut to inner core temperature dropped to 300 degrees. Cutter arbor in cold hot alternation inside produces 0.02 millimeters thermal deformation, mold side wall by milled out a path naked eye visible step.

Polishing master takes over messy stall, takes 400 grit oil stone following cavity side wall towards down pushes. Pushes to distance mouth part 150 millimeters deep position, hand feel happens sudden change. Up hard place pushes 10 times can grind flat 0.01 millimeters knife marks, down soft place pushes 3 times rapidly caves into big pit.

Handle inner core soft area polishing common tragic state:

· Use 1000 grit sandpaper grind, soft area surface however wipe from beginning to end floats a layer gray misty fog shadow.

· Wool wheel smears 5 micrometers grinding paste, slightly press heavy a bit, steel material surface drags out long reaching 2 millimeters tiny dent marks.

· Light measuring meter hits on, hard area reflectivity 85%, soft area reflectivity crazy falls to 60%, light rays scattered messy untidy.

Mold forcedly delivered to injection plant, installs on 1200 tons molding machine. 260 degrees high temperature PP plastic with per second 150 grams flow rate shoots into cavity. Injection machine pressure gauge pointer instantly soars to 110 megapascals.

Most fragile cavity bottom, exactly is that piece only has 22 HRC soft area, every time open close mold bears 30 tons local impact force.

Open machine hit not reaching 20,000 mold times, quality inspector takes vernier caliper measures just out furnace washing machine inner barrel. Barrel bottom wall thickness unknowingly unknowingly extra out 0.05 millimeters. Mold bottom soft area by high pressure plastic hard live live pressed collapsed went back.

Big steel plant comes out reach standard P20, similarly is 450 millimeters thick plate. According to craft tempers 24 hours, alloy elements in crystal lattice inside stay obediently subserviently. Saw machine cuts open two halves, hardness tester probe towards deepest place smashes.

Outer skin hardness 31 HRC, center hardness 29 HRC. Two's drop by dead dead stuck in 2 degrees within. Milling cutter from outside towards inside hollows cavity, no matter hollow how deep, machine tool spindle ammeter on pointer from beginning to end stops at 18 amperes, pointer completely no shaking.

Processing Support

Accurate Dimension & Rough Processing

Steel plant smelted out P20 mold steel out furnace time is a heavy reaching several tons big iron lump. Original blank surface covered a layer 8 to 12 millimeters thick dark brown oxide skin. Steel material outer layer carries depth 2 to 3 millimeters decarburization layer. Buyer receives a piece length width exceeds 1500 millimeters black skin big material, plant inside tens of thousands bucks bought small band saw machine fundamentally puts not down huge blank.

Deal with thickness exceeds 800 millimeters giant forged block needs to use large double column horizontal band saw machine. Machine pairs with M42 bi-metal band saw blade, tooth pitch adjusts to 3/4 TPI, line speed set at per minute 25 meters. Saw broken a piece cross section 600x800 millimeters module wants to continuously run 4.5 hours. Water based cutting fluid according to per minute 15 liters flow rate flushes saw mouth, takes away 200 plus degrees cutting high temperature.

Master in length width height three directions each leaves 5 to 8 millimeters processing allowance. Extra left a bit meat thickness used to deal with later period rough milling stage material warp rebound. Worker holding 5 meters long steel tape measure coordinates with 1000 millimeters vernier caliper measures blank, diagonal line error by dead dead stuck in 3 millimeters scale line within.

Material block by traveling crane hoists installs to 3 meters travel heavy gantry CNC milling machine work table on. Heavy 2.5 tons steel block relies on 6 pieces M24 press plate bolts fixed on carrying T shape groove cast iron platform on.

Rough processing go gnaw HRC 30 pre-hardened material, ordinary white steel cutter very easily collapses away cutter edge. Operation table changes onto diameter 160 millimeters heavy face milling cutter disc, installs on 8 pieces carrying coating hard alloy cutter blades. Machine tool spindle rotate speed set as 350 rpm, feed speed pulls full to per minute 800 millimeters.

Cutter disc cuts into steel material issues muffled metal tearing sound. Every knife cuts down 3 millimeters deep, dark gray iron filings rain drops same smash on protective cover on. Iron filings become deep blue, surface temperature fast runs to 400 degrees Celsius.

· Spindle load current monitoring peak value not exceeds 65A

· Cutter blade edge mouth flank face wear amount pressed in 0.3 millimeters within

· Water soluble cutting fluid concentration refractometer reading stable at 8%-10%

· Cut down iron filings curl into C shape or clockwork shape

Single side scrapes away 5 millimeters surface layer material, breaks steel block original stress balance. Take a piece 1000x800x300 millimeters module to say, single face rough milling finished loosens press plate, center position towards up warps up 0.8 millimeters.

Gantry milling machine master takes dial indicator hit probes bottom face, gap below pads on 0.1 millimeters thick purple copper skin find level. Reverse face cutting takes warped up deformation amount thoroughly milled flat. Two faces turning back and forth cutting, forcedly releases away material internal 70% around internal stress. Undergone rough milling go skin's half-finished product blank, thickness dimension only compared to drawing big 1.5 to 2 millimeters.

Hydraulic clamping device starts, clamping force reaches 12 MPa firmly bites steel block. Two sides independent spindle boxes according to program approach, to steel block two big faces carry out double direction scrape face.

Double head milling single side eat knife amount drops to 0.5 millimeters, cutting walk knife speed pulls up to per minute 1200 millimeters. Walk knife ends retreats knife after, quality inspector takes outer diameter micrometer calipers out dimension tolerance floats not exceeds 0.05 millimeters. Two ends parallelism error pressed in 0.02mm/100mm tolerance band within.

· Surface roughness smoothness meter tests value Ra 1.6 to 3.2

· Marble platform feeler gauge measures flatness error not exceeds 0.02 millimeters

· Digital display angle ruler verifies adjacent faces verticality error less than 0.015 millimeters

· Four corners chamfer go burrs process into C1.5 obtuse angle

Dimension processed to position steel material, four corners smear on anti-rust oil, wrap on two layers VCI vapor phase anti-rust film. Installs on wooden pallet packs sends to mold plant. Unload goods tear package after, fitter takes oil stone slightly grinds few times edge corners. Square square standard module relies on traveling crane hoist up, steadily lands at high speed processing center work table on.

Machine tool spindle on ruby probe bumps a bit steel material edge, computer screen on displayed coordinates with drawing theoretical value differs only 0.01 millimeters. Operator saved away takes divide center stick pass by pass hit meter look for coordinates trouble thing. Machine tool changes onto R4 flying cutter, rotate speed adds to 8000 revolutions, starts down knife hollow dig mold internal 3D curved surface.

Flatness & Verticality

Two pieces heavy reaching 300 kilograms P20 steel plates if at close mold time appear 0.05 millimeters error, injection machine hits out plastic outer shell edge just will hang full scraping hand flying edges.

Fine milling process takes dimension stuck into 0.05 millimeters within, but this far far reaches not precision injection mold assembly bottom line. Takes just cutting finished module puts on 0 grade granite flat plate on, uses 0.02 millimeters feeler gauge following bottom edge pushes over, edge place light easy lift just stuffed through.

"Machine tool cutting time hundreds catties press plate force one loosens, steel material surface metal fibers just like spring same towards out rebound." Old fitter's experience in front of few micrometers deformation especially accurate.

Solve flatness problem wants to change large water grinding machine to process. Work table on paved full block by block strong magnetic suction cups. Press down charge magnetism button, 120 Newtons/square centimeter magnetic force instantly takes P20 module dead dead sucks attaches on table face on, grain thread not move.

Grinding machine spindle carries diameter 400 millimeters white corundum grinding wheel, with 1440 revolutions/minute rotate speed starts transverse feed. Every time grinding eat knife amount extremely harsh, only set at 0.005 millimeters, equivalent to one root hair wire diameter one tenth.

· Grinding wheel grit size chooses 46 grit to 60 grit simultaneously cares chip discharge and smoothness

· Grinding fluid saponified fluid mixes water proportion controlled at 1 to 15

· Cooling nozzle points at grinding wheel cut in point flow rate reaches 40 liters/minute

Sparks following water flow weakly splash out. Undergone long reaching 2 hours back and forth reciprocating grinding, steel material surface walk knife knife marks by wiped flat. Steel block floats out mirror face same silver gray luster, smoothness meter measures out Ra value stable at 0.4 micrometers within.

Take down one big face, wants to continue deal with thorny verticality. Four square body steel material adjacent two faces if not is absolute 90 degrees, onto processing center drill holes time, drill bit every goes deep 100 millimeters just will skew out point two millimeters.

Cooling water channel drilled skewed, injection part cools uneven will produce warp; ejector pin hole skewed, top out time will stick dead pull hurt whole mold cavity. Machine tool master hollows out undergone measurement institute yearly inspection high precision right angle backboard, smears a layer thin thin blue oil pastes tight steel material side face grinds.

Blue oil marks can show out extremely tiny protrusions. Naked eye fundamentally sees not tilt angle, in blue white alternating spots inside thoroughly exposes.

In order to correct tiny up to tiny tilt angle, operator will at grinding machine suction cup and steel block between pad into 0.01 millimeters thick yellow copper foil. Utilize tiny tilt angle compensation, forcedly takes side face grinds to with bottom face becomes absolute 90 degrees right angle.

Inspection room inside three coordinate measuring machine takes over leave factory before acceptance judgment power. Probe on ruby ball on steel block four faces touches collects 120 data points. Computer screen jumps out inspection report shows, X axis to Y axis verticality deviation by frozen at 0.008 millimeters.

· Use 200 millimeters wide knife edge ruler let light pass method recheck big face flatness

· Four corners thickness extreme difference stuck in 0.015 millimeters boundary within

· Utilize 500 millimeters outer diameter micrometer re-measure diagonal line length difference

Takes a piece thickness 200 millimeters P20 steel six faces all grind flat, grind right angle, needs a skilled worker consumes away whole day shift's 8 hours. Single set water grinding machine one day electricity fee and grinding wheel loss just exceeds 400 yuan.

Fitter gets high precision reference material, assembles time closing eyes all can takes guide pillar smoothly pushes into guide sleeve inside. Two pieces steel plates towards press machine on one close, holding 1000 lumens strong light flashlight from behind shines, joint seam place passes not through one thread light ray.

Cooling System

250 degrees Celsius melted plastic high pressure hits into mold cavity, 15 seconds within must drop temperature to 40 degrees below then can open mold top out. Mold internal crossing vertical horizontal cooling water paths responsible takes injection produced huge heat rapidly pumps away. P20 steel block leave factory hardness maintains at HRC 30 around, wants to in pre-hardened metal inside drill out hundreds even up to thousands millimeters thin long deep holes, extremely tests machine tool processing limits.

Conventional radial drilling machine runs into length diameter ratio exceeds 10 to 1 holes extremely eats effort. Drill bit every towards down walks 10 millimeters, chip discharge groove inside iron slag just will dead dead block up cutting edge. Operator only can rely on both hands frequently lift drill retreat chips, slightly not careful, 6 millimeters thick high speed steel twist drill bit just will "pa" one sound snap broken in half meter deep blind hole deep place.

Broken in P20 mother material inside drill bit broken pieces compared to surrounding steel material still wants hard tens of degrees. Fitter only can pull come electric spark drill hole machine, soaks in kerosene inside uses thin copper tube electrode little by little go high temperature blind corrode. Take out a broken in 200 millimeters deep place drill bit tip, wants to consume away big half day shift, white white consumes electric spark machine tool 4 to 5 hours operation electricity fee.

Five axis deep hole drill abandons traditional spiral retreat chips mode, adopts internal high pressure cooling plus external discharge chips structure. A root outer diameter 8 millimeters single edge gun drill, maximum penetration travel reaches 1500 millimeters thick P20 forged block.

Machine tool starts running, spindle brings hard alloy gun drill with 2800 revolutions/minute speed rotates cuts into steel material surface layer. Cutting oil by oil pump pressurized to 8 megapascals, following drill arbor middle tiny through hole high pressure sprays to most front end drill tip position. High pressure oil fluid forcedly takes cut down broken iron filings from drill arbor outer side V shape groove inside reverse direction flushes out, hundreds millimeters travel completely not need retreat drill.

In one meter long deep hole hole path inside, drill bit skews a 0.5 degrees, exit position just will deviate drawing 10 plus millimeters. In order to suppress run skewed amount, gun drill cutter head outside welded three paths hard alloy guide blocks. Cutter bed feed speed stable at 80 millimeters/minute, hole position skew degree by forcedly suppressed in every 1000 millimeters run skewed amount not exceeds 1 millimeter extreme value range within.

Modern injection parts shape rises falls not fixed, straight line horizontally crosses water path very hard takes care to mold cavity dead corners heat dissipation. Technician in computer inside takes water path layout drawing dismantles into multi-segment space crossing tilted holes. Five axis CNC machine tool work table can carry out positive negative 30 degrees flip turning, spindle up down swings hits out carrying specific angle 3D space water path.

Targeting P20 pre-hardened steel set deep hole drilling parameters standards extremely strict:

· Hole diameter cutter tool library covers 5mm to 32mm mainstream cooling water pipe diameter requirements

· Gun drill alloy cutter head install machine before edge mouth jumping tolerance by verified in 0.015mm within

· Deep hole inner wall roughness relies on cutter head two sides guide blocks strong squeezing friction reaches Ra 1.6

· Space crossing water path converge point in order to prevent high pressure punch hole, reserve safe wall thickness lowest stuck at 5mm

Use extra long twist drill hard pulls out water path inner wall like file same rough, covered full one circle by circle thread steps. Mold onto machine pass water half month after, industrial water scale and dark red water rust just will dead dead stick in rough gaps inside, takes originally 10 millimeters thick water path blocks to only leaves 6 millimeters.

Pipe diameter one shrinks water, cooling water flow speed immediately from per second 2 meters drops to per second 0.5 meters. Injection mold local accumulates heat dissipates not out, originally 12 seconds just can out mold plastic part, forcedly prolonged to 18 seconds then can barely drop temperature fix shape. High pressure gun drill hits out hole wall smooth shiny bright, water flow completely no resistance flushes past, largely delayed water scale depositing speed.

Fitter changes onto carrying coating squeezing tap, in hole mouth towards inside 15 millimeters depth cuts out PT 1/4 taper pipe thread. Thread tooth shape full does not have broken teeth, wraps on raw material tape tighten yellow copper water nozzle after pass into 10 kilograms pressure compressed air tests, soaks in water tank inside sees not half a leak air bubble.

Complex tedious consume time deep hole drilling operations all left in rough processing workshop assembly line on digest finished. Mold plant signs receives P20 material time, internal like spider web same 3D cooling system already all pierced through and use high pressure air gun clear clean.