De “buckla” orsakas av den lokala krympningen efter att porten är förseglad eller orsakad av bristen på materialinsprutning. Fördjupningen eller mikrodepressionen på ytan av formsprutade produkter är ett gammalt problem vid formsprutningsprocessen.
Bucklor orsakas i allmänhet av ökningen av krympningshastigheten för plastprodukter orsakad av ökningen av väggtjockleken. De kan dyka upp nära det yttre skarpa hörnet eller den plötsliga förändringen av väggtjockleken, såsom bulan, baksidan av förstyvningen eller stödet, och ibland i vissa ovanliga delar. Grundorsaken till bucklan är den termiska expansionen och kallkrympningen av materialet, eftersom termoplastens termiska expansionskoefficient är ganska hög. Graden av expansion och krympning beror på många faktorer, among which the most important are the properties of plastics, the maximum and minimum temperature range and the packing pressure in the cavity. The size and shape of injection parts, cooling rate and uniformity are also influencing factors.
The amount of expansion and shrinkage in the molding process of plastic materials is related to the coefficient of thermal expansion of the processed plastics, which is called “molding shrinkage”. With the cooling shrinkage of the molding part, the close contact between the molding part and the cooling surface of the mold cavity is lost. Just nu, the cooling efficiency decreases. After the molding part continues to cool, the molding part shrinks continuously. The shrinkage depends on the comprehensive effect of various factors.
The sharp corner on the molding part cools the fastest and hardens earlier than other parts. The thick part near the center of the molding part is farthest from the cooling surface of the cavity and becomes the last part to release heat on the molding part. After the material at the corner solidifies, with the melt cooling near the center of the part, the molding part will continue to shrink. The plane between the sharp corners can only be cooled on one side, and its strength has no change The strength of the material at the sharp corner is high. The cooling shrinkage of the plastic material in the center of the part pulls the relatively weak surface between the partially cooled and the more cooled sharp corner inward. På det här sättet, a dent is produced on the surface of the injection molded part.
The existence of the dent indicates that the shrinkage of the molding is higher than that of the surrounding parts. If the shrinkage of the molded part is higher in one place than in another, the reason for the warpage of the molded part is analyzed. The residual stress in the mold will reduce the impact strength and temperature resistance of the molded parts. I vissa fall, the dent can be avoided by adjusting the process conditions. Till exempel, in the packing process of a molded part, additional plastic material is injected into the mold cavity to compensate for molding shrinkage. I de flesta fallen, the gate is much thinner than the other parts of the part. When the molding part is still very hot and continues to shrink, the small gate has been cured. After curing, the packing pressure has no effect on the molding part in the cavity.
The results show that the shrinkage of semi crystalline plastics is high, which makes the dent problem more serious; the shrinkage of non crystalline materials is low, which will minimize the dent; the shrinkage of filling and maintaining reinforced materials is lower, and the possibility of dent is smaller.
Om JasonMould Industrial Company Limited
Jasonmould är en Kina mögel tillverkare av plastformar- formsprutning, gjutformar, formblåsning av plast, rotationsgjutning, medicinsk formsprutning av plast, två skott formsprutning av plast, insatsgjutning, övergjutning, formsprutning av metall, formsprutning av mikro, formsprutning av pulver, keramisk formsprutning, formsprutning av vätskor, husky formsprutning, hushållsform, gjutform, formverktyg, anpassade formar, porslinformar, snabb prototypverktyg, verktyg för plastprototyp, stanspressverktyg, munstycke och verktyg för mobildelar/ mobiltelefondelar, bildelar, Dammsugare, uppladdningsbara verktyg, telefoner, kopiatorer, datorer, multimediehögtalare, och många andra elektroniska produkter och hushållsapparater. Och även en tillverkare av plastprodukter, mögeltillverkare Kina- plastdelar, vattentank i plast, plastbollar, plastlådor, plastspänne, plastankare, plasthängare, plastsked, rörmontering av plast, tumla av plast, porslin av plast, plastmuggar, plastflaska, plastbricka, kosmetisk behållare av plast, plastfodral, matbehållare av plast, stolar i plast, plastlock, stängning av plastlock, plaströr, vattenledningar av plast, knoppar i plast, plaströr, verktygslådor i plast, plastställ och så vidare.
Kontakt:
Person: James Yuan
Företag: JasonMould Industrial Company Limited
Lägg till: LongGang Village,LongXi Town,BoLuo County,HuiZhou City,GuangDong-provinsen, Kina
Tel: 86-752-6682869
E-post: [email protected]
Webbplats: https://www.jasonmolding.com/custom-injection-molding/
