rubutu

Roba Allura Molding Shrinkage

Gwanin gyare-gyaren allurar filastik yana daya daga cikin kaddarorin lokacin da zafin jikin kayan ya diga. Ana buƙatar ƙimar aikin gyaran allura mai ƙwanƙwasa a cikin ƙayyade girman aikin aikin ƙarshe. Valueimar tana nuna yawan raguwa wanda abin aiki ke nunawa bayan an cire shi daga sifar sannan a sanyaya shi a 23C na tsawon awanni 48.

Rinkaddamarwa ta ƙaddara ta hanyar lissafi mai zuwa:

S = (Lm-Lf) / Lf * 100%

inda S shine ƙimar raguwar ƙira, Lr ƙimar aikin aiki na ƙarshe (in. ko mm), da Lm ƙwanƙolin ƙwanƙolin ƙira (a cikin ko mm). Nau'in da rarrabuwa na kayan filastik yana da mahimmancin ƙimar shrinkage. Rinkididdigar zai iya rinjayar da wasu masu canji kamar su ƙarfin ƙarfin aikin sanyaya na ciki, allura da matsin lamba na zama. Ofarin abubuwan cikawa da ƙarfafawa, kamar fiber gilashi ko mai cika ma'adinai, na iya rage ƙyamarwar.

Rage kayayyakin robobi bayan sarrafawa abu ne na yau da kullun, amma crystalline da amorphous polymers suna raguwa daban. Duk kayan aikin robobi suna taƙaitawa bayan sarrafawa kawai sakamakon kwatankwacinsu da ƙwanƙwasawar zafin jiki yayin da suke sanyaya daga yanayin zafin aikin.

Kayan amorphous suna da ƙanƙantar da hankali. Lokacin da kayan amorphous suka yi sanyi yayin lokacin sanyaya allurar gyarar allura, sai su koma kan plymer mara tsauri. Sarkar polymer wacce ta samar da kayan amorphous ba su da wani takamaiman alkibla. Misalan kayan pf amorphous sune polycarbonate, ABS, da polystyrene.

Abubuwan da suke yin kara suna da ma'anar narkewa mai ƙyalƙyali Sarkar polymer suna ɗaukar kansu ne ta hanyar daidaita kwayar halitta. Waɗannan yankuna da aka ba da umarnin su ne lu'ulu'u ne waɗanda ke samarwa lokacin da aka sanyaya polymer daga narkakkar halinta. Don kayan polymer na semicrystalline, samuwar da kuma karin kayan da aka samu a cikin wadannan sarkakkun. Shigowar injectio na gyaran inicio don kayan semicrystalline ya fi na kayan amorphous girma. Misalan kayan adon lu'ulu'u sune nailan, polypropylene, da polyethylene.Ya lissafo abubuwa da yawa na roba, duka amorphous da semicrystalline, da kuma yadda suke kewayawa.

Ragewa don thermoplastics /%
abu rage ƙwanƙwasa abu  rage ƙwanƙwasa abu rage ƙwanƙwasa
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-nailan 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
Nylon 6 0.7-1.5 Polyethylene 1.0-3.0 PET 1.7-2.3
Nylon 6,6 1.0-2.5 Propylene 0.8-3.0 TPO 1.2-1.6
PEI 0.5-0.7        

Tasirin shrinkage mai canzawa yana nufin cewa haƙurin sarrafawa wanda za'a iya cimmawa ga polymor amorphous sunfi waɗanda suke kyallen firam ɗin kyau, saboda masu lu'ulu'u suna ɗauke da mafi umarnin da mafi kyawun sarƙoƙin polymer, sauyin lokaci yana ƙaruwa ƙwarai da yawa. Amma tare da robobin amorphous, wannan shine kawai dalilin kuma ana iya lasafta shi cikin sauƙi.

Don polymor amorphous, ƙimar shrinkage ba ƙananan kaɗan bane, amma ƙyamar kanta da sauri tana faruwa. Don polymer na amorphous na yau da kullun kamar PMMA, raguwa zai kasance cikin tsari na 1-5mm / m. Wannan saboda sanyaya ne daga kimanin 150 (zafin narkar da narkewar) zuwa 23C (zafin dakin) kuma ana iya alakanta shi da coefficient na thermal expando.


Post lokaci: Sep-19-2020