Plastic injection molding machinery is capable of injecting plastic resin into a mold and applying heat and pressure to it to produce plastic components at a very high speed. Precise timing of all pressures and temperatures is an especially critical factor for this high-speed process. Until recently, one major manufacturer of plastic injection molding machinery could only identify incorrect pressures, temperatures, or timing issues during product development or field service. What’s more, the instrumentation they used was bulky and awkward to move.

Application Summary
At various stages in the injection molding process, a plastics manufacturer ensures that its plastic injection molding machinery is maintaining specified setpoints for heat and pressure. In addition, the manufacturer verifies that all changes in heat and pressure happen at a precise rate to avoid damage to the component being produced. If heat and pressure setpoints are incorrect, the end result could be a component that lacks tensile strength and/or uniform color or texture. Therefore, when designing a plastic injection molding system, it is necessary to verify that each step in the molding process meets specific, pre-determined criteria. For example, the heat and pressure sources must maintain their respective parameters for the time required in the mold. All moving parts (e.g., injection pistons and material source valves) must operate precisely within a specific tolerance. If any of these parameters are outside the specifications, the quality of the end product is compromised.

Plastic injection molding machinery consists of many moving parts, most of which are repeatedly subjected to tremendous heat and pressure. As the equipment ages, the internal moving parts begin to wear, resulting in increased vibration and a lack of precision. The condition of the plastic injection molding machinery affects the quality of the product being produced.

Potential Solution
Until recently, the particular plastic injection molding machinery manufacturer in question helped its customers monitor timing and process problems via a digital storage oscilloscope (DSO) and a digital voltmeter. Although the manufacturer’s field service personnel found the DSO adequate for the job, it was difficult to transport to field locations. In addition, many of the field service personnel found that locating the source of the machinery’s problem was a time consuming, iterative process because of the slow speed at which the process variable changed. This slowness made it very difficult to compare timing changes on the DSO’s scope.

IOtech’s Solution
The manufacturer’s field personnel selected IOtech’s WaveBook as the replacement field-test system because of its ability to collect data from up to eight sensors in one system at one time, thus saving them time in locating defective parts. In comparision, the DSO could only collect data from one sensor at one time. Also, the PC-based WaveBook enables field service personnel to clearly display timing defects and easily compare them to the rise and fall of other process variables.

Field service personnel were also impressed by the WaveBook’s ability to record files greater than 2M samples. The timing or process variable defect is sporadic. Given the DSO’s limited memory depth, field service personnel were seldom able to capture an entire process cycle. This forced them to engage in multiple captures, making it difficult to correlate events. Because the WaveBook uses its host PC’s memory and disk storage, field service personnel are now able to collect data samples at a rate greater than 200 kHz for the duration of a process cycle time. Capturing the entire cycle makes it easy to scroll through process cycles to identify problem areas.

Finally, field personnel were pleased with the WaveBook’s form factor. This compact unit fits into a briefcase or piece of carry-on luggage, making it much easier and more affordable to transport than a digital storage oscilloscope (DSO).

Conclusion
The WaveBook simplifies testing and eliminates the need for costly, specialized instruments. Its high-speed data acquisition and 1-MHz streaming to RAM make it an ideal DSO replacement for plastic injection mold machinery test diagnostics.

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