Response of a sequential‐valve‐gate system used for thin‐wall injection molding

Chen, Shia‐Chung; Chien, Rean‐Der; Tseng, H. H.; Huang, Jianguo

doi:10.1002/app.22371

Cited by 9 publications

(6 citation statements)

References 10 publications

(6 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The delay in the sequential valve gate system is critical to control the filling time during plastic injection molding. Chen et al [13] found that the commercially sequential valve gate system delay time is from 0.3 to 0.5 seconds and most affected by the pneumatic control system air pressure responding to the valve opening and closing. Larger air pressure of 100 bars may give a shorter delay time of fewer than 15 milliseconds, and this more accurate control of the on/off switch valve helps connect the flow fronts to reduce the filling pressure loss.…”

Section: Introductionmentioning

confidence: 99%

Investigation of the Large-Scale Pallet by Recycled Polypropylene and the Sequential Valve Gate System during the Injection Molding

Cheng

Tsai

Liao

2021

Advances in Polymer Technology

View full text Add to dashboard Cite

Plastic pallets are essential devices for the transport of industrial products within containers and can be made from recycled plastics to be more environmentally friendly. However, numerous thin reinforcing ribs are required to mold such large-size pallets, thereby requiring a large-scale injection-molding machine. Many filling gates can reduce the welding lines to enhance the structural strength of the pallet to achieve injection molding using a lower locking force machine. This study simulated the production of recycled polypropylene plastic pellets using a 3500-ton super-large injection-molding machine and the Moldex3D package to derive the flow analysis of the moldability. The PTC Creo software is used to construct plastic pallets ( 1100 mm × 1100 mm × 140 mm ), filled by twelve gates using a baffle cooling system. During the four-stage filling of the sequential valve gate system, the flow front spreads from the central gate to the four corners of the pallet, decreasing the number of welding lines, with an average filling pressure of 19.23 MPa by a sequential valve gate scheme which is approximately 65% of the concurrent valve gate opening scheme. The maximum clamping force by this sequential valve gate opening scheme in the molding of plastic pallet is 874.6 tons, only half of the one by concurrent valve gate opening scheme. The average welding angle was 85.7° in the concurrent valve gate opening scheme, with smaller angles than that of the sequential gates controlled scheme. The maximum temperatures during the filling by the two schemes with the concurrent valve gates opened and the sequential gates controlled were 230.5 and 232.5°C, respectively. The sequential valve gate opening scheme’s warpages are smaller than the ones by the concurrent valve gate opening scheme. The warpages of the pallet by the sequential valve gate system are smaller than the ones by the concurrent valve gate system. A higher temperature of the cooling channel and a medium level of cooling time result in lower warpage of the pallet.

show abstract

Section: Introductionmentioning

confidence: 99%

Investigation of the Large-Scale Pallet by Recycled Polypropylene and the Sequential Valve Gate System during the Injection Molding

Cheng

Tsai

Liao

2021

Advances in Polymer Technology

View full text Add to dashboard Cite

show abstract

“…Numerous remedies have been developed to eliminate the problem of a weak weld-line structure. These include control processing parameters [4 -7] to enhance the strength in the weldline area, changing geometry and gate locations [8,9] , applying additional schemes to increase the melt temperature [10,11] , and developing theoretical models to predict weld-line strength [12,13] .…”

Section: Introductionmentioning

confidence: 99%

The influence of level of interfacial healing on the weld-line strengths of injection molded parts

Huang¹,

Wu²,

Chang³

et al. 2012

Journal of Polymer Engineering

View full text Add to dashboard Cite

Weld lines are commonly present within injection-molded plastic components and generally reduce strength. In designing a plastic part, the designer can often vary the wall thicknesses, or move the gate locations to position the weld line, so that its structural loading is minimized. By altering such variables as melt temperature, mold temperature, and packing pressure, slight increases in weld-line integrity can be achieved. These approaches often do not increase the part strength or performance to an acceptable level, resulting in the exclusion of numerous applications for plastic conversion. This study investigated a hot runner system, sequential valve gates, and heat degree, to achieve economical methods for predicting weld-line properties. By calculating melt front temperatures with MoldFlow analysis, we can predict the strength of the weld line according to the definition of " heat degree " , which is the effective cross-sectional area of the melt front multiplied by the temperature gradient. An effective crosssectional area of the melt front is defined as the area of the temperature above the melting point. In contrast to the test result, when the " sum of heat degree " is lower than 1150 mm 2 ° C for PA6 (Mitsubishi 1030J) and 500 mm 2 ° C for polypropylene (PP) (FCFC K1012), the molecules cannot bond adequately at the interface of the melt fronts. Therefore, the mechanical property declines significantly.

show abstract

“…Their experimental results indicated that the overflow trap can change the location of weld lines and move these defects into an unimportant area. Chen et al8 developed a gas‐driven sequential valve gate system for molding parts with thin walls. The system supported the rapid control of the sequence in which the gates are used to allow the melt to fill the cavity.…”

Section: Introductionmentioning

confidence: 99%

Enhancement of weld line mechanical strength using a novel ejector‐pins compression system

Shen

Huang

2012

J of Applied Polymer Sci

View full text Add to dashboard Cite

This study proposes a novel ejector-pins compression system (EPCS) to improve the mechanical strength of weld lines that are formed in the injection molding process. Weld lines are significant defects that affect injection molding quality, causing the poor appearance and low mechanical strength of injection-molded parts. In this experiment, several ejector pins are placed intentionally near the weld lines appearing, and are initially sunken beneath the cavity surface to form a reflow trap such that some of the molten plastics are allowed to flow into it during the filling process. These molten plastics are then compressed by the arisen ejector pins. Accordingly, the compressed molten plastics reflow through the weld lines, disordering the molecular orientation. Experimental verification revealed that the use of an EPCS can efficiently eliminate the orientation of the molecules parallel to the weld line. The specimens' impact strength of using EPCS can increase to between one and two times than that of conventionally injection-molded. Therefore, this simple and novel method is feasible for greatly improving the mechanical strength of weld lines. V C 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 128: 509-516, 2013

show abstract

Response of a sequential‐valve‐gate system used for thin‐wall injection molding

Cited by 9 publications

References 10 publications

Investigation of the Large-Scale Pallet by Recycled Polypropylene and the Sequential Valve Gate System during the Injection Molding

Investigation of the Large-Scale Pallet by Recycled Polypropylene and the Sequential Valve Gate System during the Injection Molding

The influence of level of interfacial healing on the weld-line strengths of injection molded parts

Enhancement of weld line mechanical strength using a novel ejector‐pins compression system

Contact Info

Product

Resources

About