Online control of the injection molding process based on process variables

In this work, a procedure is reported which is suitable to analyze online the quality of molded parts in terms of shrinkage. The procedure is based on the evaluation of the average solidification pressure, namely the average along the thickness of the pressure at which each layer solidifies, a parameter which is known to correlate well with shrinkage. The calculation of this parameter normally requires the estimation of the solidification history, information which is currently not reachable experimentally. The procedure reported in this work allows adoption of the pressure evolution measured by a piezoelectric pressure transducer to make an estimation of the solidification profile and thus of the average solidification pressure. The procedure is applied to the data of shrinkage measured on an amorphous PS and a semicrystalline iPP in a wide range of processing conditions.

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“…2 Matching eqs 3 and 6, and rearranging, one obtains the relationship for local pressure profile (valid for t > t sol and Fo > 0.1).…”

Section: ■ Experimental Sectionmentioning

confidence: 98%

Adopting the Experimental Pressure Evolution to Monitor Online the Shrinkage in Injection Molding

Speranza

Vietri

Pantani

2012

Ind. Eng. Chem. Res.

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“…Both control methods reduced variance in part weight. Michaeli et al (2004Michaeli et al ( , 2009) developed an online cavity pressure controller, which realized a constant gradient of the cavity pressure during the filling phase and calculated the cavity pressure with a PVT optimization in the holding pressure phase. They indicated that the specific volume displays a significant dependence on the viewed disturbance variables, in particular the melt/mold temperature.…”

Section: Development Of Process Control Methods With Polymer Pvt Propmentioning

confidence: 99%

PVT Properties of Polymers for Injection Molding

Jian¹

2012

Some Critical Issues for Injection Molding

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“…The above studies used different types of sensors, mostly flat specimens in the same thickness for research, while seldom discussing the molded part in nonuniform thicknesses. The injection molding process often uses direct cavity pressure for real-time monitoring and control, as the cavity pressure has higher accuracy than the pressure in other positions, e.g., pressure of hydraulic line or injection nozzle [37]. Installing the cavity pressure/ temperature sensor in the cavity can obtain an accurate history profile; however, the molded product of the cavity will be faulty.…”

Section: Introductionmentioning

confidence: 99%

Correlation between runner pressure and cavity pressure within injection mold

Tsai

Lan

2015

Int J Adv Manuf Technol

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Cavity pressure in the injection molding process is closely related to the quality of the molded products and is used for process monitoring and control to upgrade the quality of molded products. However, the sensor installed inside the cavity makes the molded product of the cavity defective, reducing productivity. In view of this, this study investigates the correlation between melt pressure and cavity pressure in different runner positions and determines the appropriate runner position, where the runner pressure can represent the cavity pressure, in order to increase productivity. First, the Taguchi method is used to obtain the optimal parameter combination of injection molding, and then, the experiment is conducted based on this condition in order to discuss the difference between runner and cavity pressure history profiles. According to the experimental results, the quality of molded products can be monitored and controlled by installing sensors at different runner positions, and the maximum value of the cavity pressure profile varies with the runner position. When the distance between the top of the pressure sensor mounted in the secondary runner and the outside diameter of the runner is greater than the maximum thickness of the molded product, the obtained pressure history profile approximates to that inside the cavity. In other words, the runner pressure can represent the cavity pressure. Mold temperature significantly influences the runner pressure history profile and form accuracy (contour precision) of the lens during the injection molding process, which can be used as a process monitoring and control parameter. In addition, the cavity pressure profile at the cooling stage is closely related to the form accuracy of the lens and is the key to determining process monitoring and control parameter.

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Online control of the injection molding process based on process variables

Cited by 56 publications

References 7 publications

Adopting the Experimental Pressure Evolution to Monitor Online the Shrinkage in Injection Molding

Adopting the Experimental Pressure Evolution to Monitor Online the Shrinkage in Injection Molding

PVT Properties of Polymers for Injection Molding

Correlation between runner pressure and cavity pressure within injection mold

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