Poob ua npuas ncauj casting (evaporative qauv casting) yog ib qho ze-net-zoo li hlau ua tshuab uas siv expendable EPS ua npuas ncauj qauv es tsis txhob ntawm cov khoom siv quav ciab los yog ntoo qauv. Molten hlau vaporizes tus qauv ua npuas ncauj thiab sau cov pwm kab noj hniav, ua tiav castings tsis muaj kab sib cais thiab tsis xav tau cov xuab zeb cores. Kev tswj cov txheej txheem tsis raug ua rau cov pa roj carbon inclusions, gas porosity thiab dimensional variation, uas tsub kom cov nqi rejection rau poob ua npuas ncauj casting qhov chaw. Cov lus qhia no taug kev los ntawm cov txheej txheem tag nrho, cov kev qhia tshwj xeeb, qhov zoo thiab qhov tsis zoo, qhov tsis xws luag casting, thiab muab kev sib piv ncaj qha nrog kev nqis peev casting, pab cov neeg kho tshuab thiab cov kws tsim khoom xaiv txoj kev tsim khoom rau cov khoom siv hlau.
1. Dab tsi yog Poob Foam Casting?
Poob ua npuas ncauj casting yog ib txoj kev ploj tuag uas tshem tawm cov tsoos xuab zeb casting txwv. Es tsis txhob cais cov pwm nrog cov kab sib faib thiab sib sau cov xuab zeb cores, cov tuam txhab tsim cov khoom loj. nthuav polystyrene (EPS) ua npuas ncauj replica ntawm qhov kawg. Cov qauv ua npuas ncauj yog coated nrog nyias txheej refractory, faus rau hauv xoob, unbonded qhuav xuab zeb, thiab compacted nyob rau hauv lub tshuab nqus tsev siab. Thaum molten hlau yog poured rau hauv lub rooj vag system, lub siab kub pyrolyzes tus npaus qauv mus rau hauv cov pa roj thiab carbon residue. Cov roj khiav tawm los ntawm cov txheej txheej thiab cov xuab zeb qhuav, thiab cov kua hlau ua kom tag nrho hloov cov ua npuas ncauj los ua ib qho khoom hlau casting tom qab txias.
Qhov sib txawv loj tshaj plaws los ntawm cov pa casting: tsis muaj kab sib cais, tsis muaj cov kaum sab xis, thiab tsis muaj cov xuab zeb sib cais. Qhov tshwj xeeb tshwj xeeb no ua rau cov txheej txheem zoo tagnrho rau qhov chaw nyuaj nrog nkhaus sab hauv ntws.
2. Step-by-Step Poob Foam Casting txheej txheem ntws
Tag nrho cov khoom ua ntu zus ua raws li 7 theem meej yam tsis muaj pwm sib dhos:
- EPS Ua Npuas Ncauj Qauv Fabrication: Txiav los yog txhaj-pwm cov khoom EPS ua npuas ncauj rau hauv cov duab kos ntawm qhov tiav lawm; kua nplaum cais ua npuas ncauj ntu ua ke los ua cov rooj sib txoos ua ke.
- Pattern Tree Assembly: Pab pawg ntau tus qauv ua npuas ncauj rau hauv cov npuas dej thiab cov kab khiav haujlwm los tsim cov pawg casting, txhim kho kev tsim khoom.
- Refractory txheej & ziab: Muab tag nrho cov ua npuas ncauj rau hauv cov dej-raws li cov slurry ntau zaus los tsim cov txheej tuab, roj-permeable; tag nrho cua-qhuav txhua txheej los tiv thaiv txheej tawg thaum lub sij hawm nchuav.
- Sand Filling & Vacuum Compaction: Muab cov coated ua npuas ncauj rau hauv lub lauj kaub tais diav; Sau lub khob nrog xoob qhuav silica xuab zeb thiab co lub khob kom ntim cov xuab zeb nyob ib ncig ntawm txhua qhov chaw. Siv lub tshuab nqus tsev txuas ntxiv los tuav cov xuab zeb nruj yam tsis muaj tshuaj binders.
- Molten Hlau Pouring: Ncuav cov kua nplaum rau hauv lub sprue; cov hlau kub vaporizes tus qauv EPS thiab zuj zus ntxiv cov pwm kab noj hniav. Lub tshuab nqus tsev siab ua kom cov xuab zeb ruaj khov thaum cov pa roj los ntawm cov npuas decomposition vents tawm ntawm cov xuab zeb.
- Txias & Shakeout: Cia lub casting solidify kiag li. Tso lub tshuab nqus tsev thiab co tawm cov xuab zeb qhuav qhuav, uas tuaj yeem rov ua dua rau cov khoom siv tom ntej.
- Kev ua tiav tiav: Txiav tawm lub qhov rooj kaw lus, tshem tawm cov txheej txheej seem, moj tej tawg huv si, thiab ua machining kom tau raws li qhov kawg qhov yuav tsum tau.
3. Cov Lus Qhia Tseem Ceeb: Kev kam rau siab & Nto Zoo
Poob ua npuas ncauj casting muab qhov zoo sib xws qhov tseeb thiab qhov chaw tiav ntawm cov pa xuab zeb casting thiab peev casting. Tag nrho cov txiaj ntsig hauv qab no qhia txog cov qauv tsim khoom lag luam.
- Dimensional kam rau uaDaim ntawv pov thawj: ISO 8062 CT7-CT9; linear kam rau ua ncav cuag ± 0.5-1.0 mm rau feem ntau qhov ntev. Ntxiv kev zam tsis tau (± 0.5 hli) tshwm sim ntawm txhua qhov sib txuas ua ke ntawm cov qauv ua npuas ncauj.
- Nto Roughness (Ra)6.3-12.5 μm; ib tug faint foam hlaws zoo nkauj tseem nyob rau ntawm casting nto, smoother tshaj ntsuab xuab zeb casting tab sis tsawg polished tshaj peev castings.
- Yam tsawg kawg ntawm phab ntsa Thickness: 3 hli rau aluminium alloys; 4.5 hli rau ferrous hlau (cam khwb cia hlau thiab hlau). Cov phab ntsa nyias nyias yuav ua rau cov hlau tsis muaj zog ua ntej thiab txias kaw qhov tsis xws luag.
- Machining Allowance: 1.5-3 mm rau ib qhov chaw; qhov ze-net-shaped tsim drastic txo tus nqi ntawm post-casting machining ua hauj lwm.
- Daim Ntawv Thov: Zero lub kaum sab xis xav tau. Vertical phab ntsa thiab undercut nta tuaj yeem nrum ncaj qha yam tsis muaj kev txwv tshem tawm.
4. Lub ntsiab zoo ntawm Poob Foam Casting
Poob ua npuas ncauj casting muab kev lag luam meej thiab tsim cov txiaj ntsig rau nruab nrab-rau-loj nyuaj castings:
- Tsis muaj parting kab lossis Flash: Cov qauv ua npuas ncauj ib leeg tshem tawm cov pwm cais kab nkaus. Tsis muaj flash los zom tawm, txiav ua tiav kev ua haujlwm tseem ceeb.
- Tsis xav tau Sand Cores: Complex internal kab noj hniav, nkhaus ntws raws thiab qhov muag tsis pom kev tuaj yeem ua ke ncaj qha rau hauv cov qauv ua npuas ncauj. Kev hloov pauv ntawm cov tub ntxhais kawm thiab cov tub ntxhais tawg tsis xws luag raug tshem tawm tag nrho.
- Zero Draft Angle Design Freedom: Cov neeg tsim qauv tsis tas yuav ntxiv cov kaum sab xis rau cov qauv ejection, uas yooj yim rau ib feem geometry thiab optimizes lub zog ntawm cov qauv.
- Tsawg Tooling Nqi & Lub Sijhawm Lead luv: EPS ua npuas ncauj qauv yog pheej yig los tsim nrog CNC kub-hlau txiav; qauv txhuas lub sij hawm yuav luv luv mus rau 1-3 hnub yam tsis muaj nqi hlau txhaj tshuaj tuag.
- Recyclable Qhuav Sand: Unbonded qhuav xuab zeb tuaj yeem rov qab siv dua tom qab shakeout, txiav cov nqi raw khoom thiab txo cov khoom pov tseg piv rau resin-bonded xuab zeb casting.
- High Batch Consistency: Cov pwm ntim tag nrho thiab lub tshuab nqus tsev ua kom txo qis qhov sib txawv ntawm qhov sib txawv ntawm kev tsim khoom, tsim rau ntau qhov ntau thiab tsawg los ntawm cov qauv me me mus txog qhov ntau lawm.
5. Cov kev txwv & yam tsis xws luag hauv Poob Foam Casting
5.1 Cov kev txwv tseem ceeb ntawm cov txheej txheem
Poob ua npuas ncauj casting muaj qhov kev cai ciam teb uas tsis tuaj yeem tshem tawm tag nrho los ntawm txoj kev kho:
- Precision tsis tuaj yeem phim cov peev casting. Nws tsis tuaj yeem ua tiav cov qib CT4-CT6 nruj rau cov qib siab lossis cov iav tsom iav ultra du.
- Cov pa roj carbon monoxide yog ib qho kev pheej hmoo uas tsis tuaj yeem zam rau cov hlau thiab hlau castings, tshwm sim los ntawm EPS ua npuas ncauj pyrolysis.
- Nyias-wall Cheebtsam (hauv qab qhov tsawg kawg nkaus phab ntsa thickness pib) feem ntau raug kev txom nyem los ntawm misruns thiab tsis tiav filling.
- Cov hlaws ua npuas ncauj zoo nkauj tawm ntawm qhov pom ntawm cov nplej uas tsis tuaj yeem tshem tawm tag nrho yam tsis muaj kev sib tsoo hnyav.
- Cov txheej txheem tsis haum rau high-temperature superalloys thiab titanium alloys vim yog cov pa roj carbon ntau heev thiab tsim roj.
5.2 Feem ntau qhov tsis xws luag: Carbon Inclusions & Porosity
Feem ntau poob ua npuas ncauj casting tsis ua haujlwm yog los ntawm ob lub hauv paus tsis xws luag: carbon inclusions thiab gas porosity.
Carbon Inclusions (Lustrous Carbon Defect)
Thaum EPS ua npuas ncauj decomposes nyob rau hauv molten hlau tshav kub, tsis tiav gasification tawm cov khoom carbon soot thiab tar residues daig tawm tsam qhov chaw casting. Cov pa roj carbon dissolves rau hauv ferrous hlau, ua rau deg carburization, machinability tsis zoo thiab inconsistent kev kho cua sov.
Main triggers: excessively high EPS foam density (above 24 kg/m³), low pouring temperature, and low-permeability refractory coating that blocks gas venting.
Gas Porosity
Qhov loj ntim ntawm hydrocarbon gas yog tsim thaum ua npuas ncauj pyrolysis. Yog tias cov roj tsis tuaj yeem khiav los ntawm cov txheej txheej thiab cov xuab zeb sai txaus, cov npuas npuas ua rau hauv cov hlau ua kom muaj zog, tsim subsurface pinholes thiab blowholes. Kev pheej hmoo ntawm porosity nce siab thaum lub tshuab nqus tsev tsis txaus lossis txheej txheej permeability tsawg dhau.
Ntxiv qhov tsis xws luag xws li xuab zeb adhesion (burn-on), txias kaw los ntawm qeeb hlau sau, thiab qauv vau thaum lub sij hawm xuab zeb compaction.
6. Poob Foam Casting vs Investment Casting (Post Wax)
Cov lus hauv qab no sib piv cov kev ntsuas tseem ceeb thiab kev lag luam nyiaj txiag los txhawb kev xaiv cov txheej txheem:
| Metric | Poob Foam Casting | Investment Casting (Poob Wax) |
| Dimensional kam rau ua | CT7-CT9 (± 0.5-1.0 hli) | CT4-CT6 (± 0.1-0.3 hli) |
| Nto Roughness (Ra) | 6.3-12.5 hli | 1.6-6.3 hli |
| Yam tsawg kawg ntawm phab ntsa Thickness | 3 hli (Al); 4.5mm (Hlau / Hlau) | 1.0-1.5 hli |
| Kev faib kab | Tsis muaj | Yog (los ntawm wax ntoo sib dhos) |
| Draft Angle | 0 ° xav tau | 1-3 ° feem ntau yuav tsum tau |
| Main Defect Hom | Cov pa roj carbon inclusions, gas porosity | Plhaub cracking, ciab residue inclusions |
| Tus nqi cuab yeej | Tsawg (ua npuas ncauj qauv) | High (hlau wax txhaj tshuaj tuag) |
| Qhov zoo tshaj plaws Batch Loj | Nruab nrab mus rau loj ntim (50-50,000 pieces / xyoo) | Me me mus rau nruab nrab precision batch |
| Haum Qhov hnyav | 0.5 kg mus rau ntau pua kilograms | Feem ntau me me mus rau nruab nrab precision qhov chaw |
Txoj cai xaiv tub ntxhais: Xaiv qhov poob ua npuas ncauj casting rau loj, complex, nruab nrab-precision ferrous castings nrog txoj hauv kev. Xaiv peev casting rau nyias-phab ntsa, siab kam rau ua me me qhov yuav tsum tau zoo heev nto tiav.
7. Haum Alloys & Yam Poob Ua Npuas Ncauj Casting Parts
7.1 Siv tau hlau Alloys
- Tsim nyog heev: Grey hlau, ductile hlau, carbon steel, low-alloy steel, aluminium alloys (tsawg carbon risk).
- Kev siv tsawg: Stainless hlau (kev tswj nruj ua npuas ncauj kom tsis txhob muaj cov pa roj carbon monoxide).
- Tsis pom zoo: High-temperature superalloys, titanium alloys, thiab high-precision non-ferrous alloys prone to carbon contamination.
7.2 Hom Poob Foam Casting Parts (poob npuas casting qhov chaw)
Cov txheej txheem no yog dav siv rau cov kua fais fab, automotive thiab industrial machinery Cheebtsam nrog complex internal kab noj hniav:
- Pump lub cev, valve lub cev thiab hydraulic manifolds nrog nkhaus sab hauv ntws raws;
- Cav thaiv, lub tog raj kheej taub hau thiab tso pa tawm manifolds rau cov khoom siv tsheb;
- Heavy-duty hydraulic vaj tse, gearbox casings thiab yeeb nkab fittings;
- Compressor vaj tse thiab loj mechanical structural castings tsis nyias tav.
Kev taw qhia tus qauv: Xaiv qhov poob ua npuas ncauj casting rau tuab, cov phab ntsa zoo ib yam. Zam qhov chaw nrog ntau cov tav tav thiab cov ntu ultra-thin, uas ua rau txhaws qhov tsis xws luag.
8. Cov lus nug uas nquag nug
8.1 Puas tuaj yeem plam ua npuas ncauj ua cov castings nrog xoom parting kab?
Yog lawm. Cov qauv ua npuas ncauj ib leeg tshem tawm cov pwm sib cais tag nrho, yog li tsis muaj kab sib cais lossis flash tshwm ntawm qhov ua tiav casting. Tsuas yog cov kua nplaum sib txuas ntawm cov ntu ua npuas ncauj tawm ntawm qhov me me offsets.
8.2 Vim li cas cov hlau poob ua npuas ncauj raug kev txom nyem los ntawm cov pa roj carbon monoxide?
EPS ua npuas ncauj qauv yog ua los ntawm polystyrene (carbon-hydrogen polymer). Pyrolysis tsim cov pa roj carbon ntau ntau. Yog tias cov npuas tsis tuaj yeem ua kom tag nrho cov pa roj carbon monoxide, cov pa roj carbon monoxide nkag mus rau hauv cov hlau molten thiab nce cov ntsiab lus carbon. Qhov kev pheej hmoo yog qis dua rau aluminium castings vim qhov txo qis ntawm qhov kub thiab qis carbon dissolution.
8.3 Cov txheej txheem twg raug nqi tsawg dua rau nruab nrab ntim loj castings: poob npuas lossis peev casting?
Poob ua npuas ncauj casting tau qis dua cov cuab yeej ua ntej thiab qis dua tus nqi tsim khoom ib qho rau nruab nrab-rau-loj castings. Kev nqis peev casting tsuas yog kev lag luam rau me me high-precision qhov chaw uas tsis tshua muaj txiaj ntsig txhua xyoo.
8.4 Dab tsi yog qhov zoo tshaj plaws EPS ua npuas ncauj ntom kom txo cov pa roj carbon tsis zoo?
Qhov zoo tshaj plaws ceev yog 22-24 kg / m³ rau hlau thiab hlau castings. Densities above 26 kg/m³ drastically increase carbon inclusion risk, while excessively low density (typically below 18 kg/m³) raises the risk of foam pattern collapse during sand filling.
9. Cov Lus Qhia & Kev Xaiv Cov Lus Qhia
Lub hauv paus ntsiab lus tseem ceeb rau kev xaiv poob ua npuas ncauj yog nyob ntawm kev sib piv cov txheej txheem kev ua tau zoo rau koj qhov geometry, kam rau ua thiab ntim ntau lawm:
- Xaiv qhov poob ua npuas ncauj castings rau nruab nrab-rau-loj castings nrog txoj hauv kev ntws ntws, xoom qhov yuav tsum tau ua kab, thiab qhov siab me me (CT7-CT9). Nws txo cov nqi machining thiab txo cov qauv coj ua lub sij hawm luv luv.
- Zam cov txheej txheem no rau cov phab ntsa ultra-nyias, cov khoom me me uas muaj qhov tseeb, thiab cov alloy castings rhiab heev rau cov khoom khaws cia; xaiv peev casting hloov.
- Control three key process parameters to minimize defects: keep EPS foam density within 22–24 kg/m³, use high-permeability refractory coating, and maintain the correct pouring temperature to ensure complete foam gasification.
- Rau kev cai poob ua npuas ncauj casting qhov chaw, paub meej tias qhov tsawg kawg nkaus phab ntsa thickness, kua nplaum sib koom ua ke, thiab alloy carbon rhiab heev nrog koj cov foundry ua ntej ua tiav cov duab kos.
