Abstract: The critical dimensions of product samples made during a standard certification procedure for an injection molding process are measured and a loss factor value is computed for each such dimension. Using statistical techniques, the largest loss factor value is partitioned into percentages of loss contributed by a predetermined set of loss elements. The loss element contributing the largest percentage is corrected so as to improve the quality of the process and the product. The method provides a way of determining what kinds of process corrections will most effectively improve product and process quality.

Abstract: An injection molding machine control device where mold element separation distance is measured and integrated as a function of time while moldable material is being introduced in the mold cavity between the mold elements. When the integral value reaches a preselected value, the mold injection pressure is changed and the moldable material is allowed to cure within the cavity.

Abstract: A method and an apparatus for monitoring the process stability of an injection molding machine having a reciprocating screw engaged in the plasticating of a moldable material in preparation to its being introduced into the mold cavity. The invention involves the measurement of the duration of the operation of the screw engaged in the plasticating of the moldable material and includes the analysis of this duration over a period of time thus providing the supervisor with the necessary information to determine whether the machine/process is meeting or deviating from the desired operating requirements.

Abstract: An improved technique for use with a molding apparatus having a pair of separable mold elements and forming a mold cavity therebetween which includes a means for opening and closing the mold elements and a means for introducing a moldable material into the mold cavity at a first pressure and for exerting a second pressure on the moldable material as it cures in the cavity has been developed. The technique involves measuring the separating distance of the mold elements while the moldable material is being introduced into the cavity and integrating the separation distance as a function of time. When the integral value reaches a preselected value, the mold injection pressure is changed and the moldable material is allowed to cure within the cavity.

Abstract: A molding machine having a pair of separable mold elements forming a mold cavity therebetween is arranged for separation along a part-line. Means is provided for controlling the molded product which comprises means for measuring the separation of the mold elements resulting from the introduction of the moldable material into the mold cavity. Means is provided for detecting a predetermined separation of the mold elements, and means is provided for changing the pressure from the first pressure to the second pressure in response to the detection. The separation measuring means is arranged to measure the separation of the mold elements following changing the pressure. Means is provided for sensing when the separation of the mold elements stops increasing and for determining whether the cessation occurs within a predetermined cessation window. Means is provided to generate a signal if the cessation is not within the window to indicate that the cycle has exceeded the product limit.

Abstract: A method of operating an injection molding machine having a pair of separable mold elements forming a mold cavity therebetween with means for opening and closing the mold elements with means for introducing a moldable material into the mold cavity at a first pressure and for exerting a second pressure on the moldable material as it cures in the cavity. The method controls the molded product and comprises the steps of closing the mold elements and introducing a moldable material into the mold cavity. The separation of the mold elements is measured during the injection of the moldable material and a predetermined separation of the mold elements is detected. Upon detecting the predetermined separation the pressure is changed from the first pressure to the second pressure and the separation of the mold elements is continued. Measurement of mold element separation is continued and the cessation of the increase in the separation of the mold elements is detected.