Technology of injection molding machines, to some degree, reflects the level of basic industry including mechanics, electronics and hydraulics. As people have higher requirements of thinner plastics parts with more steady size, higher-level of precision and shorter molding cycle, as well as stronger environmental awareness, demands for advanced injection molding machines with faster clamping performance, higher clamping precision, equal distribution of clamping force and high degree of adjustability are increasing. Due to the disadvantages of high cost, high energy consumption and unstable injection molding, traditional toggle machines tend to be replaced by two-platen injection molding machines and all-electric injection molding machines.
Two-platen injection molding machines have distinct advantages listed below compared with toggle machines:
(1) 30% smaller size of the overall machine that saves space of the workshop.
(2) Larger mold capacity and longer mold opening stroke make production of deep-cavity parts available.
(3) Four clamping cylinders get pressure at the same time. Equal distribution of clamping force on the mold that has longer service life.
(4) Automatic compensation from the lubricating pads of four cylinders under mold height change thanks to equal distribution of clamping force. Hardly any flashes of the plastic products.
(5) Less moving parts, less maintenance of the machine and more energy-saving: traditional injection molding machines are made up of many moving components such as toggles, toggle pins and crossheads, which are heavy and have high requirements on maintenance. For two-platen injection molding machines, their moving parts are replaced by hollow pistons and thus have less and more simple surface, saving kinetic energy.
(6) Larger space between tie bars, without restriction from the toggle layout and limitation of the moving platen.
(7) Larger mold opening force and mold opening under high pressure available with four clamping cylinders. More suitable for manufacturing products with deep cavities and of complicated shapes.
(8) Faster mold clamping and opening. Moving platen of the two-platen injection molding machine is driven by two cylinders, with higher operating speed, shorter response time and higher productivity.
(9) Short tie bars and adaptable locknuts which are convenient for adding function of tie bar extraction.
(10) Adjustable clamping force for protecting the mold.
In western countries, medium and large two platen injection molding machines are replacing traditional toggle machines massively. Die casting machines with two-platen clamping units also become mutual in technology. Typical manufacturers of those new injection molding machines include KraussMaffei，ENGEL，HPM，SACMI NEGRIBOSSI, Milacron, LS, Toshiba and Mitsubishi. Western two-platen injection molding machines vary in design and structure: Some have fixed tie bars and platen, clamping cylinders mounted on the moving platen and locknuts that offer pressure; some have clamping cylinders mounted on the fixed platen and lock nuts mounted on the moving platen; and some have an extra support plate at the rear end.
Western injection molding machines, represented by KraussMaffei’s MX series that consists of machines ranging from 850T to 4000T, have outstanding merits such as compact and simple structure, high-rigidity platens, reliable locknuts with little oil stains, fast clamping, stable production and high repeatability. They have been widely applied in middle and high end automobile industry including car trim and high-load parts. In 2011, BMW placed an order for a large MX 4000-24500 injection molding machine to produce instrument panel carriers.
In foundry industry, Daimler AG introduced Italpress’s TF series 3200T two platen die casting machine to manufacture parts for Mercedes-Benz. BMW bought Buhler’s Carat 4000T two-platen die casting machine in 2008 for developing magnesium-aluminum cylinder block casting. Germany’s DGS Company used Carat 2800Tdie casting machine to manufacture auto parts which have large size, thin wall and excellent mechanical performance.
China’s manufacturers began to develop large two-platen injection molding machines over a decade ago, but failed to achieve significant technical breakthrough. Limited by instability and high manufacture cost, domestic two platen injection molding machines have far less market share compared with toggle type injection molding machines. On the other hand, mature two platen injection molding machines are in an urgent need to substitute the traditional machines. Whoever masters the latest technology can seize larger market share in auto industry in the future.
In 2012, taking world-leading technology as benchmark, Yizumi set about R&D of two platen injection molding machine and aimed at making breakthrough in the machine stability, reliability, operation precision, rigidity, efficiency and energy consumption. The newly-developed machine was expected to reach or be close to the highest level in order to provide another satisfactory choice for customers.