What is the Difference Between P20 and P20+Ni | 1.2311 vs 1.2738

When selecting materials, large molds prioritize 1.2738, small molds or ordinary molds use 1.2311, direct machining after pre-hardening reduces heat treatment deformation.

Mold Size & Hardenability

1.2311 (P20)

A piece of 1.2311 steel plate with length and width each 800 mm, thickness 400 mm, roasted in an 860-degree furnace for 8 hours. After burning through, the crane threw it into an oil tank filled with 50 tons of warm oil to drop temperature. The outer 50 mm contacts the flowing oil, temperature can drop 25 degrees per minute.

This steel material's thermal conductivity performance is only 34 W/(m·K), heat cannot dissipate out. Walking inward to the 200 mm center position, temperature can only drop less than 5 degrees per minute. Inside 1.2311 there is only 1.5% chromium and 0.4% molybdenum, carbon composition about 0.3%, completely cannot block such a slow cooling speed.

The internal metal structure cannot become solid, becoming as soft as half-cooked rice. Workers take a hardness tester to cut open and measure, the outer surface's hardness can reach 30 HRC. Probing down to 150 mm deep, hardness dropped to 27 HRC. The most center's hardness only has 24 HRC left.

The hardness differing by 6 HRC makes the machining master very headachy. Tool head rotation speed opened to 2500 revolutions per minute, when cutting the surface layer it cuts very fast, machine tool current steady at 15 amperes. Waiting until the tool digs down to the deep place, the sound starts to become muffled, machine tool current randomly jumped to 22 amperes.

Internal becoming soft does not equal easy to cut, soft and loose material becomes sticky.

· Skin cutting: runs 120 meters per minute, blade almost no wear

· Internal deep digging: speed dropped to 80 meters per minute to prevent machine tool vibration

· Deep hole drilling: iron chips cannot exhaust out, often snapping the drill bit stuck in the hole

The mold went on the polishing table, the master takes 800-grit sandpaper facing the bottom to back-and-forth polish. The steel material surface is one piece soft one piece hard, soft places are very easy to be polished off a bit more. Taking high-precision instruments to scan, the surface is entirely fine undulating waves with high-low difference of 0.005 mm.

Taking the mold carrying fine undulations to produce glossy plastic parts, the injection molded outer shell surface will bring its own layer of un-wipeable white fog. The mold loaded into a 1500-ton injection molding machine, dead-pressing the 240-degree plastic raw material into the cavity using 120 megapascals of pressure.

The center zone only has 24 HRC's hardness, cannot carry the huge squeezing of 8 seconds each time. After continuously hitting 50,000 times of plastic parts, the three-coordinate instrument re-measured and found, the bottom has already been pressure-collapsed and sunken by 0.03 mm. Workers on the assembly flow line touch it, the pieced-together plastic outer shell seam area has obvious hand-scraping feeling.

· 100 to 250 mm thick: hardness very uniform, suitable for making high-precision parts

· 250 to 350 mm thick: anti-pressure becomes weak, digging deep grooves downwards must slow down speed

· Approaching 400 mm: can only make rough parts not needing grinding and polishing

Single side thickness crossing over 200 mm, the deep place's metal then lost high-pressure carrying capacity. Forcefully increasing the thickness of this steel plate on the drawing, has already exceeded the physical endurance limit of 1.2311 material.

1.2738 (P20+Ni)

A piece of 1.2738 extra-large steel block with length and width each 1.5 meters, thickness reaching 1000 mm was pushed into the heat treatment bogie hearth furnace. The metal giant object weighing up to 17 tons stayed in the 880-degree furnace chamber for a full 24 hours.

The burned-through huge steel block was craned into the 150-ton volume high-speed circulation quenching oil pool. Facing the metal wall with doubled thickness, the strong oil flow of 5 meters per second cannot take away the center region's heat within one hour.

In the 500 mm deep hinterland, temperature drop is extremely slow, per minute can only drop temperature by about 2 degrees. Inside the 1.2738 recipe was specially added 0.9% to 1.2% of nickel (Ni) element.

The trace amount of nickel changed the internal atoms' recombination path. Under extremely slow cooling speed, carbon atoms are dead-locked in the crystal lattice, unable to run outward to form loose pearlite.

The quality inspection department cuts down a test sample block, using ultrasonic hardness tester from outside to inside continuously hitting points 60 times. Skin hardness test result is 32 HRC, going deep inside 500 mm reaching the absolute center, the screen displayed number is 30 HRC.

A full one meter's thickness span, the up-down hardness drop is dead-pressed within 2 HRC. The internally extremely uniform dense bainite structure, let the 5-axis gantry milling machine master in the workshop put down the hanging heart.

The machine tool loaded a flying cutter disk of 80 mm diameter, spindle rotation speed set at 1800 revolutions per minute. From the skin first knife cutting down, straightly digging to the 600 mm deep bumper cavity bottom, the spindle load current dead-bites at 18 amperes.

The entire cutting process had no rebound brought by hardness sudden change, did not encounter the sticking knife when hitting soft material.

· Surface fast roughing: cutting bite amount single side 5 mm, iron chips present uniform silver-white

· Deep cavity curved surface finish milling: feed speed maintained 2500 mm per minute, machine tool extremely stable

· Ultra-deep waterway drilling: 1.5-meter long deep hole drill bit hits through in one breath, chip exhaust smooth without breaking drill

The workshop recorded the single piece of cutting insert's cutting life data under different depths:

The polishing worker holding 3000-grit diamond paste, cooperating with wool wheel high-speed grinds on the car front face grille's complex curved surface.

From the surface straightly extending to the 800 mm deep cavity bottom, the metal matrix's friction resistance force against diamond micro-particles is completely consistent. After continuously grinding three days and three nights, the roughness measuring instrument probe pulls once, the whole area numerical value stabilizes at Ra 0.08 microns.

Under the blinding shadowless lamp, the entire mold cavity cannot find orange peel lines generated by microscopic high-low undulations. The high-glossiness car center grille is injection molded out, surface reflection is as clear as a mirror surface.

The car front face mold weighing up to 15 tons was loaded onto the 3300-ton super large injection molding machine. Every time producing a product, the screw takes the three kilograms heavy 230-degree PP melt glue, using 150 megapascals high pressure violently pours it into the cavity.

The up to 800 mm deep bottom surface, every square centimeter hard-carries 1.5 tons of explosive shooting impact. The center region's still firm 30 HRC hardness, makes the metal matrix like a solid load-bearing wall, easily resolving the impact force.

After continuously high-intensity running 300,000 mold shots, the mold was pulled back to the fitter area to conduct all-around maintenance. The three-coordinate measuring instrument probe goes to touch the deepest place's assembly hole position, size deformation amount is merely only 0.01 mm.

Size did not run off, the hit-out car bumper installed on the car frame fits tightly, surrounding gaps uniformly kept at 2 mm. 1.2738's unit price is higher than conventional material by 3 yuan per kilogram, the early stage input was smoothed out by extremely low mold repair frequency.

Large mold factories when opening material preparation list, encountering large size parts without hesitation knock down 1.2738 in the material column.

· 75-inch TV rear shell mold: thickness 650 mm, ensures large flat surface injection molding does not warp and deform

· New energy car door panel mold: thickness 850 mm, carries the high-pressure clamping force of large injection molding machines

· Sanitation garbage bin large mold: thickness approaching 1000 mm, guarantees deep bin bottom strength does not collapse

Heavy machine tool's processing fee is up to 300 yuan per hour, whole area consistent hardness lets the machine tool 24 hours full load run without stuck knife. The workshop production scheduler calculated one milling cutter can run 12 hours.

Workers on time change knife, the accident occurrence rate of knife head suddenly breaking and scraping-scraping the mold cavity in deep night dropped to the lowest. Scrap-ruining one set of large mold's material fee is up to a hundred thousand, processing fee hundreds of thousands starting step.

Design change needs to conduct argon arc welding repair welding at 500 mm deep position. Arc temperature instantly surges to 3000 degrees, local region is thoroughly melted.

Welding wire composition and matrix fuse, cooled heat-affected zone hardness is only higher than surroundings by 1 to 2 degrees. Fitter takes a file to trim the weld scar, hand feel is extremely smooth, completely lacking file-immovable hard knots.

Un-added nickel's ordinary thick plate deep place's material leans soft, after being heated then cooled, local hardness surges to above 40 HRC. Mold repair master extremely loathes soft-hard uneven half-cooked material, one knife cutting over snaps off quite a few blades.

Selection Indicators

1.2311 steel material's current market benchmark price is about at 12.5 yuan per kilogram. Facing that set of 320 mm thick microwave oven mold, material size is set to 800x600x320 mm. Calculating by 7.85 density, steel material gross weight is about 1.2 tons, buying back this steel plate's bare material cost is roughly 15000 yuan.

In this thickness interval, 1.2311 center position's hardness still can steadily prop at around 27 HRC. Injection molding machine every day uses 90 megapascals high pressure continuously hitting out 2000 ABS plastic shells weighing 600 grams, the cavity completely carries the daily wear. Forcefully changing the material to added-nickel 1.2738, material fee needs to shell out nearly 3000 yuan more.

Mold factory procurement department has an unwritten dead rule: as long as drawing marked thickness is lower than 350 mm, close eyes filling 1.2311, inside this line buying added-nickel material purely belongs to wasting profits.

Sight moved to that set of 680 mm thick car dashboard mold drawing, two meters long, one meter five wide huge steel block lets total weight wildly surge to 16 tons. Calculating by 1.2311 material fee is exactly 200,000, changing to nickel-containing 1.2738, per kilogram unit price instantly jumped to 14.8 yuan.

The 2.3 yuan price difference multiplied by 16 tons weight, procurement budget out of thin air gets 36800 yuan more. Finance seeing the more than thirty thousand yuan extra on the report will definitely frown. The workshop director flipped open past years' machine tool maintenance account book, this more than thirty thousand if not spent now, later machine tool processing and polishing's rework fee will need to fill a deep pit of three hundred thousand.

· Tool loss account: using 1.2311 milling 680 mm thick plate, encountering soft material extremely easy to stick knife, one box of 500 yuan flying cutter inserts originally could continuous-axle rotate four shifts, now two hours just must all scrap replace.

· Machine tool work hours account: to prevent deep cavity violently shaking knife, gantry milling machine with 250 yuan hourly shift fee must slow down, feed amount dropped from 2500 to 1500, processing period forcefully dragged from 100 hours to 140 hours.

· Try-mold claim account: dashboard leather grain surface appeared microscopic concave-convex undulations, car factory returns one set of 15 tons heavy mold's back-and-forth logistics and on-machine re-try fee, one mold will just burn away a full twenty thousand.

After thickness breaks through 400 mm, 1.2738 internally extremely uniform 30 HRC hardness smooths out all hidden expenses completely. The 140 hours of processing time was steadily pressed back to normal 100 hours.

The polishing workshop's master takes wages by square centimeter piece-rate, processing 1.2738's surface has totally no hindrance. A 2 square meters flat leather grain surface, pushing 1200-grit sandpaper over friction force is completely consistent. The process originally needing four days to hand over work, in three and a half days can push onto the quality inspection tabletop for acceptance into warehouse.

Large injection molding machine's scheduling table full load runs, stopping machine to repair mold once, every day throws away in vain 8000 yuan's equipment depreciation fee, plus 3000 sets of car injection molded parts piled in the shipping area unable to be delivered.

The extra 15% to 20% material premium, buys the peace of continuously not repairing mold for half a year after mold goes on machine. Car factory demands the mold to guarantee 500,000 mold shots non-damage life, dashboard main body weighs up to 3.5 kilograms. Under the high heat roasting of molding once every 65 seconds, the deep layer metal's propping force decides the entire set of mold's life and death.

Hitting the abacus finely is a workshop craft, blindly saving money or randomly spending money will all issue serious financial accidents. A mold factory making plastic turnover boxes, drawing bottom plate thickness exactly stuck at 380 mm. Technician for the sake of trying mold seeking stability, secretly fully changed 1.2311 inside the BOM list to higher unit price 1.2738.

One ton price difference more than two thousand yuan, a set of four tons heavy turnover box mold out of thin air spent nearly ten thousand more. This factory one month consecutively opened twenty sets of same size molds, two hundred thousand's pure profit soundlessly evaporated on the account book. 380 mm is completely within 1.2311's physical endurance firing range, the more spent money did not exchange for any visible capacity lifting.

Selecting steel material is just like building a building hitting foundation, building a three-story building's base insisting on hitting piles according to fifty-story skyscraper's specification, that is pure family-ruining behavior. Using a vernier caliper to card-dead this thickness life-death line, left of line is the saving money detailed account book, right of line is the bottom line for mold to preserve life.

· Single side thickness < 350mm: dead-defend 1.2311, corresponds to rice cooker, washing machine front door ring etc. conventional injection molded parts.

· Single side thickness 350-400mm: look at appearance requirement, high-gloss mirror surface choose 1.2738, ordinary frosted internal structural parts continue to use 1.2311.

· Single side thickness > 400mm: mandatory put on 1.2738, corresponds to car bumper, center console etc. large volume strong load-bearing parts.

Weighing up to 12 tons, single side thickness 550 mm giant mold bottom plate was hoisted by overhead crane onto 3300-ton injection molding machine. Internal 0.9% trace nickel element silently endures one ton per square centimeter's melt glue washing. The material code signed and finalized on the procurement list, at the moment high-temperature plastic shot out just doomed the future three years' mold repair bill.

Surface Finish & Polishability

Satisfying Conventional Demands

Take a router base commonly seen at home as an example, outer shell thickness roughly 2.5 mm, material is PC plus ABS plastic. The mold used to produce it, is basically cut out using a piece of 1.2311 steel block length and width each 500 mm, thickness 200 mm.

Lathe master getting the blank steel plate, doesn't need to do annealing softening, bringing it over can just go on machine tool. It leaves factory bringing its own 280 to 320 HB hardness, cemented carbide tool cutting it is very smooth-handed.

Machine tool spindle rotation speed opened to 6000 revolutions per minute, walking knife speed pushed to 2500 mm, the cut down dark blue iron chips will roll curls dropping down.

In the industry for ordinary plastic parts' appearance there is a set of SPI standard, using it to make C1 to B2 level's ordinary surface is very relaxed.

· Surface carrying a bit frosted feeling sweeping robot chassis

· Outer shell carrying 0.05 mm fine lines electric drill

· Hidden inside car dashboard cannot be seen load-bearing bracket

· Thickness at 1.5 mm TV remote controller back cover

Steel material just coming down from CNC machine tool, surface will leave behind lines of rough knife marks, roughly having Ra 1.6 microns deep. Mold master will drip a bit of kerosene, holding 320-number aluminum oxide oilstone, following one direction using force to push-grind.

After the most protruding knife marks are ground flat, master will change to 400-number and 600-number water sandpaper. Every time changing sandpaper must change a 45 degree angle crossing to polish, completely covering the print left by the previous procedure.

One skilled worker purely hand polishing 4 hours or so, steel material surface's roughness just can drop to between Ra 0.2 to 0.4 microns.

Walking to current procedure, majority of daily use products' molds can be counted as polishing finished, surface will reveal out metal gloss carrying slight fog surface. Putting the polished mold onto injection molding machine with 400 tons clamping force, hitting in 220-degree plastic solution, the made out product appearance is just very flat-neat.

Insisting on forcing it to make fully transparent acrylic parts, or extremely high reflectivity computer monitor frame, the material's own foundation just cannot carry it. Master changes on above 800-number fine sandpaper, even using 3-micron thickness diamond paste to high-speed polish, defects immediately will come out.

Placing under magnifying glass to look 50 times, 1.2311's inside mixes very small sulfide and phosphide impurities. Limited by early steelmaking process, its sulfur content is permitted to reach about 0.03%, the relatively soft non-metal impurities and steel material's own wear resistance have very big difference.

Forcefully making very bright surface, extremely easy to make out the below few big troubles:

· Wool ball 1500 revolutions per minute friction will pull out fine pockmarks

· Surface friction heating exceeding 150 degrees easily bulges up orange peel-like wave lines

· Leaning soft regions looking under light will have water wave-like dark shadows

· Using potion corrosion to make texture time deep-shallow not same, drop difference can reach 0.05 mm

Taking a piece of large steel block thickness 400 mm for example, from most outside digging inward 200 mm to center part, Rockwell hardness will slowly drop from 30 HRC to 26 HRC. Internal structure not tight enough, gives polishing bottom of mold made relatively deep increased very big resistance.

Putting down extremely harsh requirements for mirror surface, its popularity rate in factories extremely high has economic account to be calculated. Buying a piece of 1.2311 on market, expense roughly only is one third of imported high-end material.

Relatively small material loss, lets a 80 yuan 12 mm flat-bottom knife's life be 30% more. Exempted from deformation risk brought by re-burning red quenching, making a set of 3 tons heavy washing machine outer shell mold, within 35 days steadily deliver goods.

High Gloss & Precision Etching

Factory master when making mold will decisively change material to 1.2738 steel added with roughly 1% nickel element.

Even if it is a piece of giant steel billet length width exceeding 1.5 meters, thickness reaching 800 mm, from outermost layer all the way downward digging to deep place's center part. Its every region's Rockwell hardness all can dead-bite within the 28 to 32 HRC interval.

The SPI-A2 even A1 level top optical mirror surface often talked in workshop, entirely relies on material internal extremely uniform hardness indicator to underprop. After grinding sandpaper all the way to 1500-number, polishing worker will change on diamond grinding paste carrying 1-micron ultra-fine particles.

Polishing machine rotation speed pulled high to 8000 revolutions per minute, cooperating with pure cotton polishing wheel on mold surface repeatedly drawing figure 8. Without the deep-shallow uneven leaning soft regions, originally extremely easy to bump into orange peel lines and tiny pockmarks are thoroughly suppressed.

Taking a strong light flashlight sticking to metal surface illuminating, reflection is extremely flat-neat, completely cannot see wave-shaped dark shadows. When processing high-end plastic parts requested complex surface etching textures, 1.2738's uniform structure revealed out extremely big processing advantage.

Making car interior often adopted VDI 3400 standard's 36 to 45 number roughness deep imitating leather grain. Workers need to take nitric acid solution concentration proportioned at 1.05 to 1.15 grams per cubic centimeter, uniformly spray inside mold cavity.

Acid liquid downward corrosion speed completely depends on steel material internal pure degree. After adding nickel element, steel material's grain size was refined to above 8 level, metallographic structure arranged as neat and uniform as lined-up soldiers.

The depth potion penetrates down can be precisely controlled within 0.02 mm, washed out texture edge is uncommonly sharp. Demolded out plastic parts, leather grain's stereoscopic feeling and real leather are very close, completely having no deep one piece shallow one piece alopecia areata feeling.

When challenging high difficulty mirror surface or fine texture, several procedures' operating standards are carded extremely strict:

· Using 600-number to 2000-number's six passes of water sandpaper level-by-level cross push grinding

· Smearing 0.5-micron specification imported grinding paste to conduct high gloss tail-finishing

· Workshop temperature strictly maintained at 22 to 24 degrees Celsius preventing thermal expansion and contraction

Taking a 65-inch OLED TV's ultra-narrow frame for example, width usually only is 3.5 mm, demanding surface reflection rate reaching above 90%. Mold factory shipped over weighing up to 2.5 tons 1.2738 blank, went on 5-axis machining center day and night non-stop milling 72 hours.

Cemented carbide tool cutting away several hundred kilograms of scrap iron after, the left behind mold cavity bottom still maintains extremely high metal compactness. Unneeded to worry digging to inside will bump onto loose softened layer, the polishing group leader taking over subsequently doing work has very much bottom in heart.

BMW or Audi car door interior panel's large area litchi grain, to mold cavity surface's etching process is a big exam. Platemaking workers will stick onto steel material surface a layer of photosensitive film thickness only being 0.015 mm.

Through high-intensity ultraviolet exposure and developing, regions not being protected just expose in the configured chemical potion. Soaking time up to 45 minutes, acid liquid eating into steel material's speed is completely synchronized, extremely rarely appearing local over-corroded pits.

Injection molding machine mold pulled open, injection pressure set at 120 megapascals, 240-degree PC plus ABS plastic liquid fills full every tiny pit. The made out interior panel surface matte feeling is extremely uniform, under natural light naked eyes cannot see out slightest color difference.

Facing different surface processing processes, every item parameter performance is very stable:

A set of large TV frame mold solely pure hand polishing fee just needs to spend 50,000 yuan, etching procedure still must extra shell out 30,000 yuan.

On material selection coveting saving money used ordinary material, arriving at the last step polishing polished out several naked-eye visible pockmarks, the front hundred hours' machine tool processing fee all hits water float.

Per kilogram unit price is only more expensive than ordinary material by several yuan, calculated down a piece of large template totally spends several thousand yuan more. But in front of high-end mold casually costing hundreds of thousands, what is bought is extremely low material loss and almost zero rework rate.

Arriving at injection molding workshop, mold can endure up to 500,000 times above opening-closing mold high pressure cycle. Every time injection cycle set at 35 seconds, extremely strong surface wear resistance preserved plastic parts' glossiness will not happen obvious attenuation following time.

Machinability and Tool Wear

1.2311's Cutting Performance

Inside 1.2311 steel material is equipped with 1.30% to 1.60% manganese, also bringing less than 0.030% sulfur, this bit of trace sulfur when cutting can act as natural lubricant. Machine tool spindle opened to S4000 revolutions/minute, the cut down iron chips all present silver-white C-shape, length generally shorter than 15 mm.

Broken small iron chips took away absolute majority heat, cutting contact point's temperature is dead-pressed at 450°C to 550°C. Cutting fluid adjusted to 8% concentration, water pump hits out 1.5 megapascals water flow fiercely rushing toward blade. Workshop master will push cutting line speed to 150m/min, per tooth feed amount pushed to 0.25 mm, continuously rough milling 90 minutes also no need to stop machine.

Unloading tool handle putting under tool presetter high-power mirror to inspect, wear data extremely tiny:

· Flank wear amount only has 0.12 mm

· Tool tip arc not seen obvious chipping

· Surface coating intact not leaking out bottom color

Machine tool force sensor's numerical value is also very beautiful, spindle downward cutting force less than 850 Newtons, lateral thrust only has 320 Newtons. Changing onto 45 degree principal entering angle large face milling cutter disk, with 2500 mm/minute walking knife speed sweeping over steel plate bottom surface. Roughness stylus swiping once, surface finish reading steadily stops at Ra 1.2 microns.

Going on machine table hitting waterway deep holes is also completely without effort, taking M35 material high-speed steel drill bit to drill 8 mm thick, 120 mm deep hole. Rotation speed set S850, feed adjusted to 120, every time chip exhaust depth set at 6.4 mm. Metal resistance force extremely continuous, one new drill bit all the way uniform speed to bottom.

Machine tool screen's Z-axis torque number jumping amplitude less than 5%, explaining drilling resistance very stable and uniform:

· Hole inner wall roughness reaches Ra 3.2

· Size cylindricity deviation stuck within +0.05 mm

· Single branch drill bit can continuously hit through 40 deep holes

Making M10 screw bottom hole time hit to 8.5 mm, going on machine table pairing extrusion tap cooperating special oil, torque meter maintains at 15 to 18 N·m, extremely rarely happens breaking tap accident. Changing to electrical discharge machining link, this piece of material's conducting electricity and remelting performance same saves mind. Discharge gap controlled at 0.08 mm to hit 10 mm depth blind hole, spark oil hydraulic pressure set 0.2 megapascals washing.

Machine table opened to 12 amperes current, pulse width given to 45 microseconds, red copper electrode tip's volume loss rate not even reaching 0.8%. Surface burned out remelted hardened layer extremely thin, thickness only 0.015 to 0.025 mm. Taking 240-number pure aluminum oxide oilstone following texture lightly rubbing 3 to 5 back and forths, that layer of hard shell just becomes white-clean.

Day shift operator staring at machine tool dry-working full 12 hours roughing, inside scrap box also only saved down 2 boxes plus scrapped four-flute cutter inserts. Machine tool electricity meter calculated down, spindle full load cutting one kilogram iron consumes electricity only 0.45 degrees. Material block put onto slow-feeding wire cutting going up to cut 60 mm thickness, threading 0.25 mm thick brass wire, tension pulled to 1200 grams.

Soaking in 5 microsiemens conductivity water, wire cutting speed steady at 190 square mm per hour, a whole day down basically not breaking wire. After going off machine using three-coordinate hitting once, 400 mm long, 300 mm wide material plate. Diagonal warp deformation amount actual measured only 0.04 mm, unneeded again go on grinder to flatten trueing.

Digging deep groove is work that most tests material uniformity, using extending 80 mm long D16 roughing cutter to cut, radial eating knife 0.5 mm also will not trigger chatter sound. Spindle vibration amplitude was forcefully pressed within 0.005 mm. Groove bottom cut out fish scale-like knife lines fine-dense flat-neat, having no that kind of clattering joining knife steps.

Arrived at clearing corner procedure, changed on D10 ball nose cutter running finish light, rotation speed pulled full S8000, walking knife F3500. 0.15 mm step distance slowly sticking to R corner scraping past.

1.2738's Material Resistance

A D50 face milling cutter disk at S800 rev/minute speed bites into steel plate, cut down iron chips fundamentally cannot break off. Silver-gray metal broken chips connect into 150 mm long, 2 mm wide rolled band, following tool holder climbing upward.

Four pieces cemented carbide cutter inserts eat knife deep 1.5 mm, into group continuous cutting chips near spindle head crazily spin. Long strip-shaped iron chips edge like shaving razor blade same sharp. Thickness less than 0.1 mm broken chips dragging on just milled-flat mold cavity bottom surface, scraping out strips of 0.05 mm deep messy scratches.

Metal cut off point accumulated extremely huge heat energy, infrared temperature measuring gun caught local cutting contact point's temperature surged to 850°C. Nickel element largely lifted material's anti-tearing ability. High temperature heat cannot follow iron chips exhaust away, 80% heat all held inside cemented carbide blade.

Coated blade under 850°C high temperature continuously cutting 15 minutes, cutting edge local pans up dark red color, aluminum oxide protective film under high temperature roasting begins softening peeling off.

Machine tool operating panel's spindle load number extremely jumps. CNC system executing task of digging a 200 mm deep, 300 mm wide square cavity, load meter pointer from 45% fiercely jumps to 65%. Mechanical sensor captured spindle enduring radial thrust exceeds 1200 Newtons.

· Z-axis vibration amplitude instrument reading approaches 0.015 mm

· Spindle outer shell temperature is higher than workshop 25 degree room temperature by 12 degrees

· Lead screw motor's torque output often hits 35 N·m peak value

Viscous liquid iron mud at cutting edge tip cooling welded dead, out of thin air generated a layer of 0.05 mm thick false cutting edge. Built-up edge under per tooth 0.15 mm feed squeezing is forcefully torn. Moment of peeling off, continuously carrying taking blade's original tungsten carbide matrix also vividly bit down one piece.

Holding enlarging 50 times industrial microscope inspecting retired down tool holder. Full load cut less than 45 minutes, flank wear amount VB value just ran to 0.35 mm scrap red line. Cutting edge entirely is irregular dog-tooth shape micro-chipping, caliper measured out chipping depth commonly has 0.02 mm.

Machine tool water tank full power running, main water pump hits out 30 Bar ultra-high pressure. Two copper-made cooling fluid spray pipes dead-aim at blade and steel block's biting contact point, forcefully flushing away the high-temperature iron mud stuck on the blade.

· Water tank cutting fluid concentration forcedly adjusted high to 12%

· Every 4 hours needs toward water trough supplementing 20 liters evaporated moisture

· Industrial water chiller set temperature pressed low to 18°C running

One 8 mm thick high-speed steel drill bit drilling toward 100 mm deep steel plate inside, accompanied by extremely ear-piercing metal screaming. Spindle rotation speed was pressed low to S600, every time downward drilling chip exhaust depth dead-limited at 3 mm.

Viscous iron chips at hole bottom severely squeeze expanding, even if machine tool spindle hesitates 3 seconds not retracting tool, 8 mm thick drill bit just will be vividly twisted broken inside hole.

Making M12 thread bottom hole extremely spends effort. A sturdy spiral flute tap twists into steel plate inner wall, digital torque wrench's scale breaks through 35 N·m. Operator toward 10.2 mm bottom hole pours full high concentration sulfur-containing tapping oil, grasping wrench bar one circle one circle inward hard twisting.

Taking 15 by 15 mm square type red copper electrode burning downward 20 mm deep, slag exhaust gap forced to widen to 0.12 mm. Viscous metal melting slag blocks inside hole position cannot exhaust out, pushed electrode four corners' loss rate high to 2.5%.

Mold cavity inner wall leaves behind a layer 0.035 mm thick white remelted hardened layer. Polishing master taking 320-grit diamond file, on hand pressing 5 kilograms strength. Inside a 50 by 50 mm square block region back-forth pushed for 10-plus minutes, just barely filed that layer of hard shell out to metal true color.

Slow-feeding wire cutting machine table's feed speed drops extremely exaggeratedly. Cutting a piece of 80 mm thick material block, 0.25 mm thick brass wire feed speed falls to 130 square mm per hour. Cutting wire tension pulled high to 1400 grams, up-down water spray nozzles hit out 1.5 megapascals high water pressure.

Workshop's tool expense bill sharply rises. One box unit price 250 yuan high aluminum coated blade, half a shift just wears out scrapped. Changing on 80 yuan a box cheap yellow titanium blade going on machine testing, propping less than 15 minutes tip corner just burns into all-black flat head.

· Monthly tool consumable procurement list quota exceeds standard 15% above

· Roughing cutter bar shock absorption alloy pad replacement frequency reaches 3 weeks once

· Scrapped cutter inserts by kilogram recycling weight single machine table reaches 8.5 kilograms

Overhanging 100 mm long 20 mm end mill walking side edge finish-trimming intersection surface. Inside program left 0.2 mm allowance to cut, thin long cutter bar was severely pushed away by hard metal wall. Taking micrometer carding inner wall, 100 mm high vertical depth, upper end and lower end measured out 0.08 mm slope difference.

Running curved surface R corner finish-trimming totally relies on bit-by-bit hard grinding. 6 mm ball nose cutter rotation speed pulled full to S12000, walking knife speed dropped to F2000. Step distance set extremely small 0.08 mm, cut down iron chips like fine-dense steel wire ball, dead-tangled on only 6 mm thick cutter bar neck.

Processing & Consumables

Workshop order scheduling system inputs same size 600 by 800 mm mold base. Operator getting 1.2311 material block, barcode scanner inputs system after rated machine tool processing working hours stops at 45 hours. Bringing nickel 1.2738 steel plate scans code into warehouse, scheduling system jumps out estimated duration climbs to 56 hours.

Roughing procedure selects D63 flying cutter disk assembling 6 pieces conventional coated cutter inserts. Processing 1.2311 setting S850 rev, walking knife F1200. Single piece cutter insert continuous cutting 100 minutes just on flank pans up slightly white wear.

Changing to 1.2738 steel plate on machine table, rotation tachometer pointer is forcedly pressed low to S600, walking knife speed falls below F800. High aluminum content TiAlN coated blade procurement unit price 65 yuan. Cutting 45 minutes after coating surface layer turns black brightening up, cemented carbide bottom color exposed.

Unit price 28 yuan ordinary PVD coated cutter insert cutting 1.2311 runs fully two hours cutting edge maintains sharp. Consumable report's material requisition list data disparity extremely big:

· Monthly processing 1.2311 consuming conventional cutter inserts 120 boxes, expense 33,000 yuan

· Equivalent workpiece quantity switching to 1.2738, high aluminum cutter insert consumption rises to 210 boxes

· D21 shock absorption alloy cutter bar procurement budget single month adding 15,000 yuan

· Scrapped tungsten steel by 70 yuan a kilogram pricing, bringing nickel steel ledger more out 45 kilograms scrap material

1.2311 machine table refractometer measured out concentration stays at 8%. Water pump water supply pressure maintains at 1.5 megapascals, two plastic water pipes toward cutter disk periphery spraying flushing. 1.2738 machine table refractometer reading forcedly hit to 12% above.

Spindle Center Through Coolant system (CTS) opens 50 Bar high pressure output. Ice-cold water column passing through tool handle inner 2 mm small hole fiercely smashes on tool tip contact point. Nickel-containing iron chips up to 800°C heat is instantly suppressed by water column, cooling water tank liquid level every 3 hours wildly drops 15 liters.

Stopping machine changing tool frequency pulled low machine tool spindle utilization rate. Machine table cutting 1.2738 in day shift 12 hours, operator taking inner hexagonal wrench disassembling-assembling cutter insert action repeats 14 times. In-machine residue cleaning and cutter disk clearing dust occupy large amount of running time.

Changing-installing new blade must re-touch CNC tool presetter probe. Z-axis origin re-trueing generates 15 minutes stopping machine idling period. Servo motor maintaining position locked electricity meter reading continues jumping. 1.2311 machine table one day shift only needs to stop machine change tool 4 times.

Three-coordinate measuring room returned report provides size out-of-tolerance coordinates. 1.2738 high resistance squeezing generates microscopic yielding. CNC program set side wall reserves 0.1 mm finish-trim allowance, 100 mm long cutter bar is forcefully pushed outward 0.03 mm by hard side wall.

Panel tool compensation interface needs manual inputting -0.03 correction negative value. Caliper measures 1.2311 finish-trimmed side wall. 0.1 mm allowance one knife uniformly scraped flat, form and position tolerance steadily stops within 0.015 mm standard line.

Procurement department checks the manufacturing cost outside the two models steel materials' ton price:

0.25 mm wire diameter pure copper cutting wire cutting 1.2311 material block. Wire spool per 8 meters per second feeding wire running, 5 kilograms heavy one roll copper wire continuous discharge cutting 45 hours without breaking wire.

Cutting head aiming at 1.2738 thick plate, super strong viscosity triggering short circuit breaking wire alarms frequently issue. Discharge high frequency pulse current is pressed low 15% running. Feeding wire speed pulled up to 11 meters per second forcedly exhausting slag, one roll 5 kilograms wire spool only props 32 hours seeing bottom.

Conductivity instrument's resin probe soaked in deionized water tank. 1.2738 cutting generates fine heavy metal particles massively suspending in water body. Externally connected resin environmental protection filter element normal state life 60 days, processing bringing nickel material insufficient 40 days filter net entirely blocked dead turning yellow.

Single branch procurement price 120 yuan pure red copper electrode clamped loaded on spark machine head. Electrical discharge etching 1.2311 blind hole, single branch electrode continuously burns out 8 standard depth cavities without obvious deformation. Aiming at 1.2738 material block finishing burning 3rd hole, bottom tip corner rounding out-of-tolerance scrapped.

Roughing chip exhaust belt conveyor carrying weight reflects cutting removal rate. 1.2311 cut out broken chips loosely piled inside iron box, every car weight loading full only has 150 kilograms. 1.2738 generated long strip rolled chips mutually dead-tangle.

Operator taking big iron hook taking half meter long nickel steel rolled chips using force pressing solid downwards. Occupying land same size scrap collection box, loading full bringing nickel cutting chips weight rushes to 240 kilograms. Waste material recycling truck needs to use forklift just can pick up iron box load onto truck.

Constant temperature 22 degrees precision workshop runs high-power water chiller. Processing 1.2311 spindle outer jacket circulating water temperature set at 25 degrees stable running. Processing 1.2738 generates large amount of high heat unable to follow iron chips exhaust away conducted to spindle. Water chiller compressor non-stop machine running, setting water temperature drop to 18 degrees pressing down thermal deformation.