P20 Steel Supplier | 1.2311, Pre-Hardened, Custom Cutting

When purchasing need to confirm chemical composition (such as C≈0.38%, Cr≈2%), and supports according to drawings doing ±0.1mm precision cutting, before processing suggest reserving 1-2mm allowance to improve finished product accuracy.

1.2311

What is 1.2311?

1.2311 is a piece of conventional steel plate used for making molds in factories. In Germany's standard documents it is called this name, arrived at domestic metal material market, the sign on shelves will write 3Cr2Mo. Molten iron when boiling in steelmaking furnace, workers will according to 0.35% to 0.45% proportion scatter carbon powder inside. Carbon powder put less steel plate will be soft, exceed 0.45% steel plate will be brittle like glass.

Boiler inside temperature is extremely high, 1.30% to 1.60% manganese element and 1.80% to 2.10% chromium element together melt in molten iron. Factory adds 0.15% to 0.25% molybdenum, prevents steel plate when subsequent heating becoming brittle. Steelmaking masters everyday all must stare at dashboard to clear impurities in molten iron:

· Sulfur element must be pressed low below 0.030%

· Phosphorus element cannot exceed 0.030%

· Silicon element kept in 0.20% to 0.40% range

· Residual copper element lower than 0.30%

After vacuum pumping equipment's adsorption, hydrogen gas hiding in molten steel is pumped away, concentration drops to below 2ppm. Solidified formed huge steel block is sent into 1050 degrees Celsius heating furnace roasted red. Forging machine uses several thousand tons of strength to smash down, steel block is repeatedly hammered deformed, compression ratio reaches 4 to 1.

Workshop workers put forged well steel block into 840 to 870 degrees Celsius furnace inside for heat preservation. Crane throws red-hot steel block into large water tank filled with quenching oil for rapid cooling. Steel block taken out after moves into 600 to 650 degrees Celsius tempering furnace to slowly roast. Every 1 millimeter thickness needs to roast for 2 minutes.

Factory delivery note stated status is called pre-hardened. Handed into fitter's hands when it already carries suitable hardness. Avoided second high temperature quenching tossing, a piece of 800 mm long, 600 mm wide plate, machine tool cutting processing dimension deviation amount can be controlled at 0.01 millimeter level.

Quality inspector on thickness 400 millimeters steel plate cut surface drills hole to test. Surface's hardness is stuck between 28 to 32HRC, cut open to measure the most center position, instrument displayed number is 27.5HRC. Testing pulling force's data sheet on prints several indicators:

· Yield strength 850MPa around

· Tensile strength 1000 to 1100MPa between

· Pulled broken after's elongation rate reaches 13%

· Impact testing's energy value about 35 Joules

Machine screen on inputs 150 to 200 meters per minute cutting speed, cutter teeth every time forward gnaw down 0.15 millimeters iron filings. Machine tool operation panel on's load indicator light stabilizes in 65% green zone. Cut down iron filings present C shape, length about at 10 to 15 millimeters between.

Drill bit on steel plate drills cooling water holes when, speed drops to 20 to 25 meters per minute. Hole's depth once exceeds drill bit diameter's 3 times, program will let drill bit one advance one retreat to outward discharge iron filings. Machine tool bottom's conveyor belt every hour can transport away 30 kilograms of waste iron filings.

Whole steel plate first put into oven heated to 320 degrees Celsius. Hand inside holding a piece of ER70S-6 model welding wire melts to fill. Mended finished steel plate moved to 550 degrees Celsius furnace inside stays full 2 hours. Placed under room temperature slowly lets cool, steel plate surface will not crack open.

Steel material wholesale warehouse's shelves on placed full of various sizes spot plates. Regular stocking's size specification table on lists several options:

· Cylindrical steel bar outer diameter 20 to 400 millimeters

· Long strip flat steel thickness 20 to 600 millimeters

· Steel plate width maximum can cut to 2200 millimeters

· Single block longest length retained at 5800 millimeters

Holding 220 grit aluminum oxide sandpaper to machine processing left knife marks grind flat. Change onto 320 grit, 400 grit sandpaper cross polish, all the way change to 600 grit fine sandpaper. Carrying wool felt's electric polishing machine rotating speed adjusted to per minute 3000 revolutions.

Master on cloth wheel smears 9 micrometer and 6 micrometer particles' polishing paste. Used on 3 micrometers diamond lapping paste after, steel plate surface can like mirror same reflect light. Frequently rubbed parts will be stuffed into 510 degrees Celsius sealed furnace inside roast for 40 hours. Furnace inside filled into ammonia gas, letting steel plate surface grow out a layer of hard shell.

Seeped inside's this layer hard shell thickness has 0.2 to 0.3 millimeters. Surface's Vickers hardness value soars to 600 around. Placed under microscope to measure, most outside has a layer of white compound, thickness only is 0.01 to 0.02 millimeters. Large gantry milling machine takes steel plate's six faces scrap flat, dimension error stuck within +0.5 millimeters.

Heavy reaching 15 tons large plastic box mold, assembled finished from workshop goes offline. Injection molding machine nozzle with 120 megapascals pressure takes melted plastic injected into mold. Two sides closed bear clamping force high reaching 800 tons. Machine continuously hits out 500,000 plastic boxes, mold inside's wear amount only has 0.05 millimeters.

Hard and Soft Combined

Rockwell hardness tester's diamond indenter on surface leaves a tiny pit. Dial pointer steadily stays on 30 HRC scale line. Responsible for rough processing machine tool spindle starts rotating.

A piece diameter 50 millimeters hard alloy face milling cutter approaches steel material edge. Cutting depth set as one time eating knife amount 2.5 millimeters. Spindle rotating speed climbs to per minute 1200 revolutions. Blade contacts metal instant issues low deep roaring sound.

Splashed out iron filings present bright silver gray color. Length about 12 millimeters, curled into standard "6" character shape. Steel material inside 0.03% sulfur element played natural lubricant's role. Iron filings did not stick on tool cutting edge on, following machine tool protective cover slip down to below's chip conveyor inside.

Processing carried out 45 minutes, cutting area's temperature soars to 600 degrees Celsius. Operator presses down pause button to check tools. Six alloy blades' back angle wear amount only is 0.15 millimeters. Machine tool spindle's load meter's value always stays at 65% around.

Material testing laboratory inside, pendulum style impact testing machine high high raised. Bottom fixed a piece of long 55 millimeters, cross section 10 by 10 millimeters standard test sample. Test sample middle opened a V shaped notch. Heavy pendulum smashes broken test sample, dial pointer records down 36 Joules' impact absorption energy.

Car bumper's injection molding production line on, two halves heavy reaching 8 tons molds violently close together. Machine oil cylinder applied 1500 tons' huge clamping force. Boiling hot liquid plastic with 120 megapascals high pressure rushes into mold cavity.

Cavity inner wall's steel plate outward produced tiny elastic expansion, magnitude about 0.02 millimeters. Plastic cooling setting's few seconds after, mold re-opens. Steel plate instant rebounds resets. Three coordinate measuring machine given permanent deformation data less than 0.001 millimeters.

Workshop inside's processing craft cards on records different procedures' specific cutting parameters:

· Lathe rough processing: down knife depth 2.5 millimeters, cutting line speed 180 meters/minute

· CNC fine turning: down knife depth 0.2 millimeters, cutting line speed 250 meters/minute

· Deep hole drilling machine operation: drill bit rotating speed 15 meters/minute, every time discharge chips retreat knife 3 millimeters

· Thread tap tapping: use M12 tap, cutting speed 8 meters/minute

Technician took common tools and feed speed's matching data made into an operation reference table:

Pure copper electrode approaches steel plate surface, inputs 45 amperes pulse current. Thousands and tens of thousands times' electric spark discharge takes steel material surface ablated out one by one tiny meteorite craters.

Spark discharge's gap maintains at 0.05 millimeters. Flushing fluid takes melted metal micro particles rapidly flush away. Discharge processing after, steel plate surface left down a layer white bright quenched hard layer, thickness using microscope measured out only has 0.015 millimeters.

Mold fitter holding a piece 320 grit whetstone on discharge area back and forth scrape. Both hands downward apply about 5 kilograms pressing force. White bright layer under whetstone's friction gradually falls off. Bottom original metal texture re-exposes in air inside.

Engraving machine installed a piece diameter 1.5 millimeters ball head milling cutter. In mold corner inside milled out a length width each 5 millimeters trademark letter. Spindle rotating speed soars to 18000 revolutions/minute. Feed speed drops to 800 millimeters/minute.

A piece slice specimen was placed under metallographic microscope. Lens magnifies 500 times. Field of view inside presents out tempered bainite and small amount martensite mixed tissue structure. Grain size grade reached ASTM 8 grade standard.

Length 400 millimeters, width 400 millimeters, thickness 150 millimeters processed finished part parked on inspection platform. Ruby probe on six faces point measured 120 coordinate data. Flatness tolerance stays at 0.008 millimeters.

Excellent Polishing Performance

Polishing workshop inside's lighting very bright, 500 lux illuminance hits on fitter table. A piece weighing about 120 kilograms steel plate just from CNC milling machine unloaded down, surface fully covered knife teeth gnawing left ripples. Knife marks depth using roughness meter measured out about is Ra 3.2 micrometers.

Aluminum based whetstone dipped on few drops decolorized kerosene, sticking to metal surface back and forth push pull. Master wrist downward pressing force about at 3 to 5 kilograms between.

First time lay bottom used is 220 grit silicon carbide sandpaper. Sandpaper back's back glue stuck on hard wood strip on, following same one direction forcefully rubbed for 30 minutes. Metal surface's rough milling cutter lines gradually fade away, a layer depth about 0.08 millimeters parallel scratches covers on top.

Cross number grinding process extremely consumes physical strength. Master according to sequence sequentially brings 320 grit, 400 grit, 600 grit and 800 grit water grinding sandpaper. Every time change finer sandpaper, grinding direction must with last time form 90 degrees crisscross. Steel plate surface's roughness value all the way downward falls to Ra 0.8 micrometers.

Manual sandpaper grinding ended after, pneumatic tools take over next work:

· Pneumatic ultrasonic polishing machine connected 0.6 megapascals compressed air.

· Hard wood stick chuck with per second 20,000 times frequency produces high frequency micro vibration.

· Bristle wheel on squeezed into about 2 grams containing 15 micrometers particles grinding paste.

Metal surface's matte gray color starts to fade away, floats out specific cold light. Steelmaking plant in furnace inside done vacuum degassing treatment shows out effect. Molten steel inside hydrogen gas content pressed below 2ppm, cut open surface on cannot find out one tiny sand hole.

Non-metal inclusions under microscope limited within ASTM E45 standard 1.5 grade. Master hand inside's polishing wheel if rolls over one hardness leaning high oxide particle, steel plate surface will pull out a 0.05 millimeters long scratch. Several days manual heart blood will all scrap.

Polishing room independent from outside machine processing workshop. Room inside temperature all year round controlled by air conditioner at 22 degrees Celsius. Air purifier's PM2.5 value kept below per cubic meter 10 micrograms.

Air inside tiny sand dust once drops on half-finished product cavity on, polishing cloth wheel rolls inside will scratch surface. Technician changes onto a brand new pure wool felt wheel. Holding diamond paste's syringe tube wall on marks different color codes. Red tube corresponds 9 micrometers, blue corresponds 6 micrometers.

Electric motor's rotating speed locked at per minute 2500 revolutions. Wool wheel carrying green polishing paste on steel material surface fast friction, local temperature rises to 45 degrees Celsius around. Master separated by cotton gloves can feel bursts of warm heat. Instrument's stylus on surface slides over, screen jumps out number became Ra 0.2 micrometers.

Master takes green syringe squeezes out mung bean sized paste body, inside wrapped 3 micrometers tiny diamond debris. Skimmed cotton ball tightly pinched in hand inside, using about 1 kilogram force on steel plate draws tiny circles.

Continuously rubbing for two hours after, takes industrial alcohol takes residual paste body wipes clean. Steel material surface like a clear mirror. Above 3 meters place's fluorescent lamp tube completely undamaged reflected on metal face on. A piece used to inject 55 inches TV front shell mold panel polishing finished.

Smoothness reaches standard after, inspector holds strong light flashlight sticking to surface shines, checks whether has orange peel ripples:

· Light beam with 15 degrees included angle sweeps across polishing face.

· Line of sight stays on area 100 square centimeters inspection zone.

· Surface did not appear high low undulating tiny potholes.

Steel plant inside undergone 4 to 1 large ratio forging huge steel block, internal tissue extremely uniform. Carbon element and alloy elements did not gather into clumps. Polishing wheel long time at same one position repeatedly rubs, does not have any one place because locally leaning soft being rubbed out pit.

Quality inspector used roughness meter's diamond stylus on surface slid 5 millimeters distance. Screen final frozen value is Ra 0.15 micrometers. Mold cavity edge pastes on 3 layers masking paper tape protection.

Mold transported to injection workshop installed into machine platform. Material barrel inside heated to 240 degrees Celsius polycarbonate particles melt into liquid state, rush into mold cavity. Holding pressure time set as 8 seconds, cooling water in mold internal diameter 10 millimeters pipes inside circulating flows.

15 seconds after machine ejector pin takes product tops out. Mechanical hand grabs out a transparent car headlight lampshade. Optical instrument determined lampshade surface light transmittance reached 92%. Polished well mold cavity sprayed on a layer thickness only has 5 micrometers anti-rust oil.

Get off work before worker carefully covers thick dust-proof cloth. Waiting next time injection machine turn on produce when, takes dust-free cloth wipes off anti-rust oil. Mold still can hit out surface glossiness reaching 95 GU home appliance plastic outer shell.

Pre-Hardened

Farewell Deformation & Cracking

A piece 500 kilograms heavy ordinary raw steel thrown into 850 degrees fire furnace inside roasted through, fiercely plunges into cold through oil tank. Short 3 seconds within, steel block surface temperature falls to 200 degrees below. Extreme cold hot alternation lets steel material internal expands 3% to 4%, inside has countless strands of strength crazily pulling.

Hardworking engraved out shape mold taken to furnace inside to burn, risk extremely big. Plant inside CNC milling machine day night non-stop worked 120 hours, very not easy dug out 0.02 millimeters accurate dimension. Undergone 800 degrees high temperature a round of tossing, steel material extremely easily happens twisting deformation.

Mold four edge corners cool fast, middle thick solid place cools slow. Thermal expansion cold contraction natural reaction lets originally flat steel plate warps up 0.5 to 1.5 millimeters. Assembly worker prepares to take upper lower two halves mold piece together when, facing often is a piece cannot close scrap iron.

Buy factory leaving carrying hardness steel plate, equals to take high temperature tossing work left in large steel plant's professional fire furnace inside. A piece thickness reaches 400 millimeters P20 steel plate, in plant inside experiences long reaching 72 hours slow fire baking and cooling.

Steel plant uses stairs like temperature dropping method, lets steel plate every inch temperature slowly go downward. This piece steel plate delivered to processing workshop when, stomach inside wanting to burst itself strength controlled at 20 megapascals below extremely low level.

Lathe master takes hardness at 28 to 32 HRC between P20 steel plate moves onto machine tool. Tungsten steel milling cutter with per minute 800 revolutions speed cuts down, silver gray iron filings circle by circle fly out. Downward dig 150 millimeters deep pit, side edge still keeps 0.015 millimeters up down straight state.

Self takes to burn fire become hard, most easily at weak detail positions roll over.

· Thickness not reaching 3 millimeters thin skeleton bends into bow shape.

· Exceeds 50 millimeters deep round hole, hole mouth inwards shrinks 1%.

· Carrying right angle water channel end quietly cracks open naked eye cannot see thin seam.

· Used to screw screws hole position thread pitch runs off 0.1 millimeters.

Hide away second high temperature this checkpoint, blade walks over left marks equals to final delivery's dimension. A set heavy reaching 2 tons large car bumper mold just from machine tool comes down, original seal not moving loaded car sent towards injection plant to press plastic.

Quality inspector takes three coordinate measuring machine scans one circle, whole set mold's length width dimension deviation even 0.005% all not reach. Steel plate inside's carbon, chromium, manganese etc components, early already in steel plant 600 degrees large tempering furnace inside uniformly scattered open.

This piece steel no longer carries that kind one touch then brittle temper, anti-pull strength steadily kept at 1000 MPa up down. Injection machine uses 120 megapascals huge pressure takes hot plastic liquid hits in, mold cavity carries on tens of thousands times, cannot find out a thread of crack.

A set five axis processing center engraves large washing machine outer shell mold, continuously operates 180 hours. Machine tool cuts off nearly 40% volume metal block, whole piece P20 bottom plate still flat flat neat neat.

Master takes precise dial indicator on long reaching 1500 millimeters diagonal line scratches over. Dial on pointer shaking magnitude whole process did not exceed 0.03 millimeters, totally not need take to machine on to re-grind flat bottom face.

A set slow wire cut electrical discharge machine cuts open 80 millimeters thick P20 steel block. Brass wire set per second 0.2 millimeters wire walking speed. Not let clean internal strength's steel material encounters electric spark high temperature, instantly ignited unstable gunpowder barrel.

Cut to half time steel block issues a muffled sound, 0.005 millimeters cutting gap instantly shrinks tight dead dead clamps. Brass wire on spot snaps broken, thousands of bucks buy material cost hits water drift.

Shorten Production Cycle

Factory director received a large size TV back shell mold order, delivery period stuck at tight 25 days. Bought in a piece hardness only 15 HRC soft state raw steel, just is digging empty inside that 250 millimeters deep groove, rough milling process just needs to consume away two machine tools fully 60 hours time.

Several hundred catties heavy half-finished product wants to load onto small truck, sent to 50 kilometers away heat treatment plant to queue. Heat treatment plant's furnace bottom wants to wait gather enough a whole furnace's mold material then will ignite raise temperature, just queuing number waiting furnace position wants to vainly consume away three days.

A trip complete quenching plus two times tempering process, watch hands tick tock walk over 72 hours. Small truck again runs a trip pulls back workshop, 5 days time already evaporated clean clean.

Brought back steel block under thermal expansion cold contraction natural reaction, four edge corners upwards warped up 0.6 millimeters. Worker has to take this piece blackened iron lump moves onto large surface grinding machine, spends fully one daytime back and forth push pull grind, takes deformed bottom face re-repairs flat.

Place order buy a piece factory hardness frozen at 30 HRC pre-hardened P20 steel plate. Delivery truck drives into workshop parks beside CNC machine tool, crane hoists down steel plate steadily presses on work table. Operator inputs well G code, alloy cutter head following trajectory cuts out drawing specified ultimate dimension.

Exempted sending out heat treatment trouble, saved away on road bumping and queuing waiting 120 hours time loss. Not experienced high temperature tossing steel plate bottom face flatness sticks within 0.02 millimeters, exempted going on grinding machine repairing patching 10 hours manual intervention job.

Workshop wall on's production progress table inside, records two kinds different materials walk complete all processes time expense accounts.

A set medium size car dashboard mold, originally full strike full calculate wants to spend 35 days then can send onto injection machine platform try mold. Changed into factory carrying hardness material, workers two shifts rotation continuous operate, 18th day afternoon can arrange large truck takes assembled well finished mold pull to customer deliver goods hand over job.

Self burned out iron block surface will float appear a layer 0.2 millimeters thick hardened black skin. Fine processing cutter head touches this layer hard oxide skin extremely easily chips off gap. Operator every interval 4 hours has to stop high speed rotating spindle, spends 20 minutes dismantle replace a piece value 80 bucks tungsten steel blade.

Steel plant processed well plate material internal hardness uniform, from skin downwards dig away 200 millimeters deep pit, hardness meter hits out readings all at 28 to 32 HRC between wander. A piece carrying coating round nose milling cutter can on top continuously cut 15 hours exempt change knife, late night workshop no one stare guard machine tool also can rest assured run.

Reduced out time reflects in workshop every tiny corner.

· Polishing master not need takes coarse sandpaper to grind off black skin pockmarks, uses polishing paste following bottom grain pushes, bright surface speed fast one times.

· Drill bit inward hits 150 millimeters deep water channel hole, iron filing strips smoothly fly out, machine tool spindle not need repeatedly lift up discharge chips.

· Cut off outsourced burning fire back and forth transport, quality inspector less fill out three copies material outflow inflow inspection bills.

Finance year end calculate account, saved down 18 days work hours equals to single set mold manufacturing cycle compressed half. Plant building every month extra takes down four large injection mold orders, every month paid 50,000 bucks machine tool electricity fee and labor cost, all allocated into doubled production volume income inside.

Golden Balance Point

Takes a piece hardness only has 15 HRC soft state raw steel goes to mill a set toy car mold, tool walks up indeed completely not spend effort. Takes done well mold installs onto 500 tons pressure injection machine on runs not reaching twenty thousand molds, two halves mold closing gap just by high pressure plastic rushed out tiny mouth. Just pressed out plastic toy edge grown full 0.1 millimeters long scratch hand flying edges, only can hire several workers sit at assembly line beside hold utility knife slowly repair scrape.

Changes walk another extreme, buy a piece hardness high reaching 45 HRC extra hard steel block throw on CNC machine tool. Spindle rotating speed opens to per minute 3000 revolutions, just cuts in not reaching 15 minutes, value 150 bucks imported tungsten steel milling cutter tip just chipped into sawtooth shape. Accompanied by ear-piercing metal friction scream sound, machine tool operator one day down has to scrap away more than half box expensive blades, eat knife depth only can fix at pitiful 0.05 millimeters.

Special steel plant engineers at 850 degrees quenching furnace and 600 degrees large tempering furnace between, found a precise retreat road. Takes P20 leaving factory Rockwell hardness dead dead stuck in 28 to 32 HRC interval inside. Brinell hardness meter hits out pit hole size uniformly maintained at 300 HB up down, an extremely balanced physical state formed.

Machine processing workshop's old master one side clears iron filings one side pours bitter water: "Steel material too soft, injection workshop uses few days cavity just collapses; material too hard, my side one day cuts bad a pile of tools earned money all not enough to compensate." 28 to 32 value, just well takes these two ends complaints all blocked up.

Lathe operator takes feed amount set at 0.15 millimeters, spindle keeps 2000 revolutions steady speed. Carrying coating alloy round nose cutter on this piece steel plate continuously ran 50 hours, cutter face only left down a layer extremely shallow normal wear marks. Cut out iron filings present out beautiful silver blue color, curled into 3 centimeters long spring shape smoothly drop into waste car inside, did not break into powder also did not stick on cutter arbor.

Take 1000 grit fine sandpaper go to grind soft raw iron, will feel surface issues sticky, push pull hundreds times also pushes not bright. Facing 30 HRC hardness surface, polishing worker hand inside wool wheel dips on a little diamond grinding paste. Only need back and forth rub three hours, steel plate surface just can reflect out workshop ceiling fluorescent lamp tube, roughness meter sticks on to test, value steadily stays at Ra 0.8 bright face level.

· Tool consume bill: a piece two hundred yuan alloy milling cutter can cut down 60 kilograms thick solid iron filings, midway full speed running not need stop machine change knife.

· Mold life table: carries hold 300,000 times high pressure melted plastic open close mold impact, complex cavity dimensions one move not move.

· Chemical biting flower bill: acid potion uniformly soaking 15 minutes, corroded out frosted skin texture deep shallow consistent stays at 0.03 millimeters.

Drilling machine worker holding a piece M8 tap prepares on mold base tap thread screw bolts. Raw soft material easily sticks hold tap's sharp teeth, one not careful just takes thread squeezed rotten. Meets too hard material, worker has to hold breath little by little inward spin, slightly not notice only hear one crisp sound, high carbon steel tap broken in half section hole inside, dozens catties heavy mold board almost scrapped.

Facing pre-hardened plate material, tapping machine spindle set at per minute 300 revolutions. Tap drips on two drops cutting oil, smoothly drills into bottom hole, brings out thread by thread tiny iron slag. Not reaching one minute time, a row neat uniform inner threads hit well. High strength bolts screwed in, dead dead carry hold injection machine open mold time hundreds tons instant pulling force.

Custom Cutting

Professional Precision

Worker starts a set heavy reaching 45 tons large CNC band saw machine, takes thickness fully having 600 millimeters P20 original plant steel plate slowly pushes into processing area. Machine tool base all is using resin sand casted formed, own weight enough huge, machine starts time one bit all not shake.

Two sides heavy hydraulic clamps immediately tighten, clamp on pressure gauge pointer stops at 50 bars. One hundred twenty kilonewtons strength dead dead pinches hold steel plate two sides edges, hardness at 28 to 32HRC steel material at full speed cutting time absolutely will not move half inch.

Machine inside oil cylinder pulls saw blade, always keeps per square millimeter 300 newtons constant pulling force. A piece long 8800 millimeters, wide 67 millimeters bi-metal band saw blade, is tightly stretched into a straight cutting line.

· Band saw blade leaves factory attached measured parameters

· Tooth tip material used is M42 high speed steel

· Tooth tip quenched after hardness reached 68HRC

· Saw blade steel band thickness takes caliper measures out 1.6 millimeters

· Saw teeth big small not one adopts two over three variable tooth pitch arrangement

Fifteen kilowatts main motor smoothly rotates up, machine panel on shows saw blade operation speed is per minute 24 meters. Big small not one saw teeth alternately gnaw biting hard steel plate, scraped down iron filings very easily just in wide large tooth seams inside curl up drop down.

Facing 600 millimeters thick solid P20 steel material, machine controls saw blade downward cut speed, always steadily stays at per minute 14 millimeters. Saw blade just one touches steel plate surface layer, machine inside spread out cutting sound low deep and uniform.

Cut upper side two large nozzles fiercely spray out milky white cutting fluid. Inside gear pump one minute can pump out 60 liters liquid, strong water pressure instantly takes gap inside still not in time to drop down broken iron filings washes clean clean.

· Cooling fluid peacetime mixing ratio and management standard

· Extreme pressure emulsion and tap water according to one to twelve ratio mixed

· Every day use instrument determine liquid concentration kept at percent of eight point five

· Liquid acid alkali degree all year round stabilizes at 8.8 to 9.2 between

· Roller on magnets non-stop absorb away 0.1 millimeters size fine iron filings

Worker holds temperature measuring gun hits at cutting seam deepest place, screen shows highest temperature only has 42 degrees. Band saw blade only on steel plate left down a path 2.2 millimeters wide thin narrow gap, extremely low heat instantly by flowing water stream taken away, steel material internal physical structure complete undamaged.

Per minute 200 revolutions speed, hard takes stuck in tooth seams inside curled iron filings all pick out clean, prevents these broken iron filings being brought in collapse bad saw teeth.

Cut to steel plate middle leaning lower position, sensor found hardness slightly has a bit not same. Machine in 0.1 seconds inside makes out reaction action, takes downward cut speed dropped to per minute 11.5 millimeters, operation current steadily stops at 22 amperes.

Continuously non-stop cut for 145 minutes, a piece long 900 millimeters, wide 600 millimeters, thick 350 millimeters P20 steel block was completely cut down. Workshop crane hangs four vacuum suction cups, takes this piece 1.4 tons heavy steel material steadily move away.

Holding surface roughness testing instrument on cut open face test a bit, reading shows Ra15.6. Surface touches up relatively flat, does not have that kind potholed tearing marks, subsequent processing worker takes it flat puts on electromagnetic table just can start work mill.

Inspector takes out a piece can pull to 1500 millimeters long Mitutoyo digital vernier caliper. Screen on clearly shows, this piece steel material length is 902.15 millimeters, width direction actual measured is 602.30 millimeters.

· Length width height 3D dimensions data acceptance requirements

· Length width actual dimension error in 2.0 to 4.0 millimeters within

· Thickness direction extra leave out 1.5 to 3.0 millimeters allowance

· Vertical face measurement diagonal length differs not reach 1.2 millimeters

Inspector on steel block surface smears a layer industrial used glycerin, holding ultrasonic flaw detector starts sliding check. 2.5 megahertz high frequency sound wave penetrates 350 millimeters thick steel block, screen on reflection waveform clean clean, did not appear one bit messy ripples.

A small delicate pneumatic marking machine leans on up, on steel block side fast knocks. Needle head only hits inside 0.4 millimeters deep, knocked out P20 material code, 839912 furnace batch number, also has just now manually measured out length width height specific numbers.

Protect Steel Material Performance

Workshop outside frequently sees some people holding acetylene cutting torch cut ordinary iron plate, nozzle sprayed out blue flame temperature high reaches 3000 degrees. If take this set rough brutal doing method use on P20 pre-hardened mold steel on, high temperature will instantly take steel material roast red-hot, heat follows cut mouth inwards fiercely conducts.

Cutting edge 50 millimeters range within steel material structure will be thoroughly burned destroyed. Factory self-carried 28 to 32HRC hardness under high temperature baking happens annealing reaction, all the way plunges to 20HRC below, became like raw iron same soft spongy waste material.

Wait steel plate in air inside naturally cools after, edge again will happen second quenching. Outer skin 3 millimeters thickness suddenly hardens to 50HRC above, subsequent on machine tool milling time, expensive tungsten steel cutter head bumps on hard shell will instantly chip edge.

Our plant area does not use any heating cutting equipment, all relies on metal saw teeth hard live live takes steel material little by little gnaws down. Large band saw machine cutting time produced friction heat extremely tiny, temperature measuring instrument hits on just cut open surface on, reading very rarely exceeds 42 degrees Celsius.

Huge spray pipe points at saw blade biting steel plate position, per minute pours out 120 liters industrial cooling fluid. Water flow carrying 0.5 bars pressure washes saw seam, hand touches up only has 20 degrees around slightly cool touch feeling, heat basically has no opportunity in steel material internal accumulate.

Water flow washing cut off heat conduction path. From cut mouth edge inward measures even if only 1 millimeter position, takes Leeb hardness tester continuously hit dot test five times, screen on popped out value steady proper ground stays at 30HRC around.

Not by high temperature destroyed P20 steel material, internal metallographic tissue keeps original plant uniform bainite plus martensite structure. Worker takes down a piece leftover material puts to 500 times electron microscope below observe, crystal particles arranged neat neat tidy tidy, does not have any carbide precipitated black spots.

Heat controlled well, steel material factory actual measured several physical performance indicators all qualified:

· Tensile strength testing instrument pulls broken test sample data kept at 1000 megapascals

· Yield strength pointer points at 850 megapascals scale line on does not have one bit shift

· Impact toughness machine smashes broken sample block measured out absorption energy reached 35 Joules

· Finished nitriding treatment after surface layer hardness still can soar to 650 Vickers hardness

A piece originally wanting to on large CNC machine tool mill 40 hours car dashboard mold, machine tool spindle rotating speed can rest assured open to per minute 2500 revolutions. Worker not need worry certain corner suddenly becomes hard or becomes soft, feed speed stably keeps at per minute 1200 millimeters.

Performance by destroyed steel plate to factory brought loss really too big. Scrap a piece diameter 50 millimeters imported alloy flying cutter head wants to lose 800 bucks, stop machine change knife re-align knife still wants to again delay 45 minutes delivery time.

Quality inspection department did one time detailed data comparison test, recorded different crafts to steel material destruction degree:

Polishing master gets cold cutting dropped material P20 steel block after, immediately jumps over rough grinding link. Hand inside holding 600 grit sandpaper only ground for half an hour, surface just floated out uniform metal luster, thoroughly avoided heat affected zone frequently appeared that kind hard to eliminate orange peel ripples.

Changed to 800 grit whetstone following one direction push grind, steel material surface smoothness very fast just reached Ra0.2 mirror effect. Injection machine takes 250 degrees melted state ABS plastic hits into mold cavity inside, demolded out plastic part surface like glass same reflects light.

Encounter needing to do etching texture treatment car interior part mold, preserved perfectly steel material performance played very big role. Etching potion poured on steel block surface soaked 40 minutes after washed off, corroded out skin texture depth uniformly kept at 0.05 millimeters, naked eye cannot see deep shallow not one flaws.

Warehouse inside stored 300 tons P20 original plant large plates, all according to rules lie on band saw machine material rack on queue drop material. Even if is a piece only wants 2 kilograms heavy small insert, also must walk finish 15 minutes slow speed cold cutting flow, operator absolutely will not scheme save trouble go use beside plasma cutting torch.

Formulate Industry Standard

Plant building top double girder bridge type crane slowly starts, four thick big steel wire rope lifting rings hang hold a piece long 2800 millimeters, wide 1500 millimeters P20 original plant large plate. This piece weight exceeds 12 tons solid steel block is steadily placed on material drop area heavy cast iron platform on.

Two sets specially deal with big mac size horizontal CNC band saw machines park beside. Saw beam maximum open span reaches 3000 millimeters, machine tool bottom load-bearing base uses high grade cement mixed thick steel rebars downwards cast fully 2 meters deep. Cut broken a piece thickness 800 millimeters steel plate, machine continuous axis turn works 7 hours just can get done.

Plant outside many small workshops equipment only can cut broken thickness 400 millimeters within ordinary mold steel, encounters super thick forgings only can hire truck send go out issue forging, delivery time at least backwards delays 7 days. Plant inside takes cutting thickness ceiling hard live live pushes to 1200 millimeters.

Customer received steel plate four faces all all are band saw blade left slight sawtooth ripples, taken to own machine tool on go process before still has to spend time wash flat. Workshop inside one word line open five sets double head CNC milling machines, contracted six face smooth plate processing work. Up down two loaded full 16 pieces tungsten steel blades flying cutter heads same time rotate lean on up, one knife scrapes away 3 millimeters rough surface layer.

Six face fine milling leaving factory delivery measured data:

· Length width dimension plus minus tolerance all stuck at 0.1 millimeters within

· Thickness direction tolerance dead dead controlled at +0.05 millimeters

· Six faces surface roughness all ground to Ra3.2

· Arbitrary adjacent two faces verticality deviation not reach 0.05 degrees

Office inside order arranger fingers knock few times keyboard, ERP system few seconds just takes drawn well cutting drawings transmitted to machine tool screen on. Every one path cutting instruction all carries a string independent barcode, operator holds scan code gun aiming at bill beep one sound, machine tool automatically reads out needing set cutting speed parameters starts working.

Cut down a piece gives small mold used slider steel material only has 5 kilograms heavy, load car exit warehouse before worker also will on its side paste on a piece high temperature resistant PVC label. On top clear clear printed a string 18 digit numbers QR code, contains cutting worker employee number code, drop material specific hour minute second and that day exit warehouse shift.

Take mobile phone scan a bit label on QR code, screen on 3 seconds within just will jump out this piece P20 steel plate originally is from which steel plant entered warehouse, even cut it time used away that piece band saw blade factory batch number all can check clear clear plain plain.

A piece just cut down large size module, inspector holding flaw detector on surface one scan, screen shows middle has a sesame seed size white dot defect. Cutting master operates traveling crane, takes this piece heavy reaching 600 kilograms, according to market price calculate wants 10,000 plus bucks sick steel material on spot throws into basket inside.

Customer afternoon three o'clock sends come a piece make car bumper mold material proportion bill. Excel table inside listed out 45 pieces length width thickness completely not same P20 steel materials, smallest ejector pin plate 20 millimeters thick, largest cavity mother plate heavy reaching 2 tons. Workshop inside 7 sets saw machines get drawings separately start drop knife.