Short shot refererer til fænomenet, at hulrummet i plastikformen ikke fyldes helt på grund af plastikkens utilstrækkelige flydende, resulterer i ufuldstændige plastprodukter. Hovedårsagen er forkert indsprøjtningstryk og hastighed (herunder for stort tryktab forårsaget af modstand), som primært påvirkes af følgende aspekter:
1、 Når man laver en masse knapper og andre små plastikdele
(1) Utilstrækkelig sprøjtestøbekapacitet – dette skyldes sprøjtestøbemaskinens høje kapacitet, which may also be caused by insufficient plasticizing capacity or insufficient injection quantity. The insufficient plasticizing capacity can be increased by prolonging heating time, increasing screw speed and increasing back pressure. If the injection volume is not high enough, a larger injection machine can be used to solve the problem.
2、 Improper design of plastic mould
(1) Local short shot caused by flow imbalance in each cavity of a multi cavity mold – when the injection molding capacity of the injection molding machine is sufficient, this defect is mainly caused by the uneven flow in each gate, det er, the uneven distribution of the cavity in the plastic mold.
(2) The flow range of the melt is too long and the flow resistance is too large. The parts that hinder the melt flow include nozzle, gate, runner and the thin wall of the product. By increasing the nozzle diameter / temperature and using the nozzle with small flow resistance, the flow resistance of the nozzle can be reduced.
(3) Poor exhaust. When filling the cavity, air is trapped to produce a reaction force. When the melt is injected into the cavity, the cavity is closed by the melt from the beginning, and the air is trapped in the unfilled local area. Tilsvarende, due to the high filling speed, sometimes the air does not have enough time to discharge from the plastic mold through the parting surface, but is compressed, resulting in some unfilled areas in the cavity, thus shortening the production time of the molded parts.
3、 Improper molding process
(1) Improper injection molding process – low barrel temperature, slow injection speed, short injection time and insufficient back pressure lead to plastic shortage.
(2) Excess supply of plastic – if too much plastic enters the barrel, the injection pressure is lost due to the compression of the particles, which reduces the pressure required to inject the melt from the nozzle, which is necessary for injection molding, resulting in insufficient injection pressure. The solution is to adjust the feed rate, dvs. melting rate, and make it just suitable for molding.
(3) Unstable production cycle: frequent machine shutdown and production inconsistent with normal cycle make some plastics stay in the barrel for a long time, resulting in the reduction of density and viscosity, resulting in short shot.
(4) Improper mold temperature results in lower injection rate and plastic filling.
4、 Choice of plastics
(1) Poor fluidity of plastics – if the plastic material does not have a high fluidity, it solidifies before reaching the furthest end of the cavity or before flowing into the overflow tank, which usually results in insufficient jet flow.
In order to eliminate these defects, the melt / mold temperature and injection pressure / velocity can be increased to make the melt reach the end of the cavity before solidification. det er nødvendigt at overveje, om udstyrs produktionskapacitet kan sikres før brug, large plastic fluidity is particularly important, so choosing a plastic with good fluidity is also a solution. If the flow coverage is too long and the plastic does not fill the injection molding part correctly, it is recommended to change the gate location to reduce the plastic flow.
5、 Improper product design
In the process of product design, the principle of uniform wall thickness must be followed. If the uniform wall thickness cannot be maintained, please change the plastic mold design in time. Increase the number of flow channels or ribs in areas where feeding is difficult, so as to avoid the defect of insufficient filling due to too thin wall thickness.
Kort sagt, there are many reasons for short shot, which restrict and influence each other. In order to reduce and correct this defect, we need to comprehensively consider the relationship between these aspects, constantly practice and accumulate experience, so as to quickly determine the reasons for insufficient filling, so as to reduce the waste of resources and increase the production of products.
Om JasonMould Industrial Company Limited
Jasonmould er en Kina mold maker af plastforme- sprøjtestøbeform, formstøbning forme, plastblæsestøbning, rotationsstøbning, medicinsk plast sprøjtestøbning, to skud plast sprøjtestøbning, indsatsstøbning, overformning, metal sprøjtestøbning, mikro sprøjtestøbning, pulverformsprøjtning, keramisk sprøjtestøbning, flydende sprøjtestøbning, husky sprøjtestøbning, husholdningsskimmel, støbeform, formværktøj, brugerdefinerede forme, porcelæn forme, værktøj til hurtig prototyping, værktøj til prototyper i plastik, slagpresseværktøj, dør og værktøj til mobiltelefon/ mobiltelefondele, bildele, støvsugere, genopladelige værktøjer, telefoner, kopimaskiner, computere, multimediehøjttalere, og mange andre elektroniske produkter og husholdningsapparater. Og også en plastproduktproducent, skimmel producent Kina- plastikdele, vandtank i plast, plastik bolde, plastbeholdere, plastspænde, plastanker, plast bøjle, plastske, rørledning i plast, tumlet plast, bordservice i plast, plastik kopper, plastik flasker, plastbakke, kosmetisk beholder af plast, plastkasse, madbeholder i plast, plaststole, plastikkapper, lukning af plasthætte, plastrør, vandrør i plast, plastik knapper, plastrør, brugskasser i plast, plaststativer og så videre.
Kontakt:
Person: James Yuan
Selskab: JasonMould Industrial Company Limited
Tilføje: LongGang Village,LongXi Town,BoLuo County,HuiZhou City,GuangDong-provinsen, Kina
Tlf: 86-752-6682869
E-mail: [email protected]
Websted: https://www.jasonmolding.com/custom-injection-molding/
