Plastiki jekiseni kuumbwa shrinkage ndechimwe chezvinhu kana tembiricha yezvinhu ichidonha. The mwero jekiseni Kuumbwa shrankage inodiwa kuona kwekupedzisira workpiece kukura. Iko kukosha kunoratidza kuwanda kwechidimbu icho chinoratidzwa ne workpiece mushure mekubviswa muforoma uye ndokuzotonhora pa23C kwenguva inosvika maawa makumi mana nemasere.
Shrinkage inogadziriswa neiyi inotevera equation:
S = (Lm-Lf) / Lf * 100%
uko S ndiyo mold shrinkage rate, Lr yekupedzisira workpiece zviyero (mu. kana mm), uye Lm iyo mhango mhango zviyero (mu kana mm). Iyo mhando uye kupatsanurwa kwepurasitiki zvinhu zvine musiyano kukosha kwe shrinkage. Iyo shrinkage inogona kukanganiswa nemhando dzakasiyana senge kutonhora kwesimba workpiece ukobvu, jekiseni uye kugara zvinomanikidza. Kuwedzeredzwa kwezadza uye zvekusimbisa, senge girazi faibha kana maminera ekuzadza, anogona kudzikisa shrinkage.
Shrinkage yemapurasitiki zvigadzirwa mushure mekugadziriswa zvakajairika, asi crystalline uye amorphous polima dzinodzikira zvakasiyana. Zvese mapurasitiki ekushandira anodzikira mushure mekugadziriswa kungori nekuda kwekumanikidzika kwavo uye nekupisa kwekushisa sezvo ivo vachitonhorera kubva pakupisa tembiricha.
Amorphous zvinhu zvine yakaderera shrinkage. Kana amorphous zvinhu zvinotonhorera panguva yekutonhora chikamu chejekiseni jekiseni, vanodzokera kune akaomarara plymer. Iwo ma polymer ngetani anoumba amorphous zvinhu haana chaiwo maitiro. Mienzaniso pf amorphous zvinhu zviri polycarbonate, ABS, uye polystyrene.
Mhedzisiro yemidziyo ine yakatsanangurwa sekristaro yakanyunguduka poindi Iwo ma polymer maketani anozvimisikidza pachawo akarongeka mamorekuru kugadzirisa. Idzi nzvimbo dzakarairwa makristasi ayo anoumba kana iyo polymer yatonhodzwa kubva kune yayo yakanyungudika mamiriro. Kune semicrystalline polymer zvishandiso, kuumbwa uye kuwedzera kurongedza kwemakemikari emaketani munzvimbo idzi dzemakristalline. iyo injectio kuumba shrinkage yemaminicrystalline zvinhu zvakakwirira pane zveamorphous zvinhu. Enzaniso yemakristalline zvinhu ndeyenylon, polypropylene, uye polyethylene. Inonyora huwandu hwepurasitiki zvinhu, zvese amorphous uye semicrystalline, uye yavo mold shrinkage.
| Shrinkage ye thermoplastics /% | |||||
| zvinhu | muforoma shrinkage | zvinhu | muforoma shrinkage | zvinhu | muforoma shrinkage |
| ABS | 0.4-0.7 | polycarbonate | 0.5-0.7 | PPO | 0.5-0.7 |
| Acrylic | 0.2-1.0 | PC-ABS | 0.5-0.7 | polystyrene | 0.4-0.8 |
| ABS-nylon | 1.0-1.2 | PC-PBT | 0.8-1.0 | Polysulfone | 0.1-0.3 |
| Acetal | 2.0-3.5 | PC-PET | 0.8-1.0 | PBT | 1.7-2.3 |
| Zvinhu zvenaironi 6 | 0.7-1.5 | Polyethylene | 1.0-3.0 | PET | 1.7-2.3 |
| Nylon 6,6 | 1.0-2.5 | Polypropylene | 0.8-3.0 | TPO | 1.2-1.6 |
| PEI | 0.5-0.7 | ||||
Iyo inoshanduka shrinkage mhedzisiro inoreva kuti kugadzirisa kushivirira kunoitika kune amorphous mapolymers kuri nani zvakanyanya kupfuura iwo emakristalline ma polima, nekuti macrystallites ane zvakawanda zvakarairwa uye zvirinani kurongedza kwemaketani epolymeri, chikamu shanduko inowedzera shrinkage zvakanyanya. Asi nemapurasitiki amorphous, ichi ndicho chete chinhu uye chinoverengerwa nyore.
Kune amorphous polymers, shrinkage values haangori pasi chete, asi shrinkage pachayo inokurumidza kuitika. Kune yakajairika amorphous polymer senge PMMA, iyo shrinkage ichave iri muhurongwa hwe 1-5mm / m. Izvi zvinokonzerwa nekutonhora kubva panenge zana nemakumi mashanu (tembiricha yekunyungudika) kusvika 23C (tembiricha yemukamuri) uye inogona kuve inoenderana neyakaenzana yekuwedzera kwekushisa.
