Short shot verwijst naar het fenomeen dat de holte van plastic mal niet volledig is gevuld vanwege de onvoldoende vloeibaarheid van plastic, resulterend in onvolledige plastic producten. De belangrijkste reden is onjuiste injectiedruk en snelheid (inclusief overmatig drukverlies veroorzaakt door weerstand), die voornamelijk wordt beïnvloed door de volgende aspecten:
1、 Spuitgietmachine
(1) Onvoldoende spuitgietcapaciteit – dit wordt veroorzaakt door de hoge capaciteit van de spuitgietmachine, 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, dat is, 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, poort, 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. Wanneer de smelt in de holte wordt geïnjecteerd, the cavity is closed by the melt from the beginning, and the air is trapped in the unfilled local area. Evenzo, 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, d.w.z. 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. Voor smeltmaterialen met een lage viscositeit, zoals polyamide, 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.
In het kort, 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.
Over JasonMould Industrial Company Limited
Jasonmould is een Chinese matrijzenmaker van plastic mallen- spuitgietmatrijs:, spuitgietmatrijzen, kunststof blaasvormen, rotatiegieten, medisch spuitgieten van kunststof, twee schoten spuitgieten van kunststof, invoegen lijstwerk, overmolding, metalen spuitgieten, micro-spuitgieten, poeder spuitgieten, keramisch spuitgieten, vloeibare spuitgieten, husky spuitgieten, huishoudelijke schimmel, gietvorm, matrijs gereedschap:, aangepaste mallen, Chinese mallen:, tooling voor snelle prototyping, kunststof prototyping gereedschap, ponsmachine tooling, sterven en tooling voor mobiele/mobiele telefoon onderdelen, auto-onderdelen, stofzuigers, oplaadbare gereedschappen, telefoons, kopieerapparaten, computers, multimedia speakers, en vele andere elektronische producten en huishoudelijke apparaten. En ook een fabrikant van plastic producten, schimmelfabrikant China– kunststof onderdelen, plastic watertank, plastic ballen, plastic containers, plastic gesp, plastic anker, plastic hanger, Plastic lepel, plastic pijp montage:, plastic tuimelen, plastic servies, plastic bekers, plastic flessen, plastic dienblad, plastic cosmetische container, plastic verpakking, plastic voedselcontainer, plastic stoelen, plastic doppen, plastic dop sluiting, plastic buizen, kunststof waterleidingen, plastic knoppen, plastic buizen, plastic gebruiksdozen, plastic rekken enzovoort;.
Contact:
Persoon: James Yuan
Bedrijf: JasonMould Industrial Company Limited
Toevoegen: LongGang Village,LongXi Town,BoLuo County,HuiZhou-stad,Provincie GuangDong, China
Tel: 86-752-6682869
E-mail: [email protected]
website: https://www.jasonmolding.com/custom-injection-molding/
