FOAM MOULDING | TECHNOLOGY
cally foamed gas. Woojin Plaimm said its foaming technology has a lower maintenance cost com- pared to third-party physical foaming technology. The new SFV unit is fitted with a 2400 size servo-driven rotary table that accommodates five moulds and can operate with five different mould sizes. The vertical clamping system delivers 75 tons of clamping force. The clamping station is de- signed with 200 mm of daylight. Other features of the SFV unit include installa-
instead delivers the gas volume at one rate. The gas is delivered under low pressure, Morita said. JSW jointly developed its SOFIT technology with
Maxell, and the RIC-Foam method developed at Kyoto university. With the SOFIT approach, the concentration of dissolved gas is controlled by the pressure vessel. Pressurisation of the physical blowing agent to a supercritical state is unnecessary. A density and thickness reduction of three-times that of a solid part is achievable with SOFIT, Morita said. Physical foaming was also a topic of interest at IPF for machinery group Woojin Plaimm, which is headquartered in South Korea. Two different machine models in its IPF exhibit booth produced low pressure physically foamed articles by incorpo- rating the company’s Super-Foam technology. This includes the SFV2400, Woojin Plaimm’s newly developed horizontal injection/vertical clamping super foam model, designed as a dedicated system for the footwear industry. The company developed the machine jointly with South Korean material and shoe designer Comtech Chemical (CTC). The Super-Foam Vertical (SFV) machine incorpo-
rates the company’s self-serviceable gas injection system to deliver nitrogen into the molten resin. The system is comprised of an N2 gas cylinder, 0-10 Mpa gas regulator, a gas supply tank and pressure sensor. The nitrogen is injected through a port into the injection barrel where it dissolves and dispers- es into the molten polymer before it is injected into the mould. Two nozzle injectors provide stabilised injection of the polymer-gas mix. A decompression step during the injection process grows and stabilises the bubble nuclei to produce a uniformly porous product, the company said. Users can control the degree of foam moulding by adjusting the ratio of applied resin and physi-
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tion of the company’s IMC 500 controller with 18 inch screen that manages precise injection control, and an optional automated mould exchange system that can manage thirty sets of mould settings through a mould rack management robot interface. Woojin Plaimm produced a shoe midsole from TPE in a two-cavity mould in a cycle time of 100 s in a demonstration of the technology at the IPF show. Woojin Plaimm also installed its Super-Foam technology on a DL500A5 servo-hydraulic two platen unit to demonstrate lightweighting of a test part made from a 20% glass-filled PP. By adding gas to the molten material at an 11% foam rate, part weight dropped from 316 g as a solid to 280 g as a foamed part. Cycle time was reduced to 80 s. Gas under 10 MPa was delivered into the molten resin through the Super-Foam system. At Shibaura Machine’s IPF show booth the company demonstrated a low-pressure physical foam injection moulding approach in which material foaming is conducted using compressed air under 4.3 MPa pressure along with a precisely moving core back step in the mould. Shibaura placed a gas compressor from Dubai-
based Satarco in the moulding cell, where it delivered compressed air directly into a port on the injection machine barrel. The compressed air unit controls the delivery of the gas that mixes with the molten material in the metering zone. A Plagate shut-off nozzle from Fisa controls the uniformity of the mixture before it is injected into the two-cavity test mould. Shibaura’s precision core back control detects
mould expansion due to a rise in mould tempera- ture and automatically adjusts mould movements at increments of 0.01 mm. Shibaura said part weight is reduced by 47% while cycle time, injection pressure and clamping pressure are also reduced.
CLICK ON THE LINKS FOR MORE INFORMATION: �
www.jsw.co.jp �
www.woojinplaimm.com �
www.shibaura-machine.co.jp
May/June 2024 | INJECTION WORLD 53
Left:
Masanori Morita from JSW holding a file box
moulded using the company’s SOFIT foaming process
IMAGE: M KNIGHTS
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