Hydraulic Presses Improved with PLC and HMI

Overview:

A manufacturer running 10 lines of molded plastic items suffered from poor productivity, inefficiency and a large number of operator errors. They needed an automated solution. Using a simple setup with an Omron PLC and Omron HMI, the manufacturer reduced wasted time and material and utilized his hydraulic presses to their full potential.

The Problem:

The process in question was a fully manual process. It consisted of an operator filling a mold with resin, setting the pressure, and activating the hydraulic press. The operator would wait for a given time as indicated in the “recipe”, then increase the pressure setting. The operator, again, would wait for a given time, and then disengage the hydraulic press. The mold is flipped over, and the process repeated. The total time of production for one part could run from 30 minutes to 300 minutes, depending on the resin composition and size of the finished product.

This type of process, while simple in nature, is actually inherently prone to productivity issues. The process relies completely on the operator to accurately set and control variables, such as pressure and pressing time. Human error, and unfortunately a lack of care by the operator, was resulting in these variables being inaccurate and ultimately many parts were rendered useless. On a typical day, the manufacturer had 10 presses running and was losing two parts a day due to operator error, at an average of $175 per part.

The Solution:

Our solution was to automate the process by installing an Omron CP1H PLC and an Omron NS series Industrial Touch Screen HMI on each press. The operator from then on would only need to select the “recipe” from a user friendly menu on the HMI, and press start. The PLC from then on would control the process by starting the hydraulic press, setting the pressure required, and time to hold. It would alert the operator when the process was completed, either to flip the part over or to remove the product. It also would trigger an alarm if a mechanical failure had occurred in the press and the set pressure could not be achieved.

The total cost for setting up the system, allowing for programming, hardware, and installation was $130,000.

The Results:

The manufacturer eliminated the losses due to defective products coming out of the presses. While that alone would have covered the cost of the automated solution in approximately one year and directly increase his revenue by $127,750/yr from then on, there were also added benefits that became apparent. Productivity was increased as now a visual alarm allowed the supervisor to quickly see when a press was sitting idle, and the situation corrected immediately. The solution provided also reduced the manpower required to run the ten presses from five operators to two.

Materials Used:

OMRON CP1H Series PLC with Ethernet Interface.

OMRON NS Series Industrial Touch Screen HMI, 8” with Ethernet Interface