/ Catalog / Testimonials New Controls Reduce Maintenance Costs Item 6 of 6 by David Ross, Manchester Plastics, as reported in Machinery & Equipment MRO, February, 1996, p. 30. MANCHESTER, MI-Manchester Plastics, a leading Canadian plastics producer with four plants in Ontario and three in Michigan, has cut its scheduled downtime by 80%, by upgrading injection molding machine controls to a new microprocessor design. The controls used in the past experienced frequent faults. Machine problems could not be identified except by testing multiple control circuit boards. Switching to the latest microprocessor controls has largely eliminated these problems. The new controls offer extensive diagnostic capabilities which make it easy to identify machine problems. The entire control logic is contained on a chip which has not failed to date. Finally, the new controls can easily be reprogrammed to add new machine capabilities. A good example is adding a shutoff valve that allows the screws to rotate while the old one is opening. This increased production rate by a factor of five on the machine. Manchester Plastics is a custom injection molder specializing in automotive interior trim components such as instrument panels, consoles, door panels, and miscellaneous trim. The company has four plants in Ontario and three in Michigan. Each plant has developed the specialized engineering and manufacturing talent needed to produce a certain type of interior trim product. The Manchester plant employs 200 and has grown to 160,000 sq. ft. through eight different additions. This plant uses a wide range of molding machines, including Cincinnati Milacron, Mir, Van Dorn, and others. Five years ago, the company had a wide range of control system set ups, most of which were supplied by the manufacturer of the machine. Some of these were solid state controls that used modular input and output boards to set operating logic and others were older style controls with relay logic. Many of the older solid state systems and all of the relay controls lacked diagnostic capabilities. When problems occurred, it was very difficult to locate their source. It was generally necessary to call in a factory service person even for what turned out to be very simple problems. The machine control service people could frequently order a new circuit board which took several days to arrive. Then the board would be installed and the problem would remain. This would be the first indication that the problem resided in the machine rather than in the control. In many cases one signal could go through six or seven output boards, making it necessary to troubleshoot each of these boards. In addition, the contacts on the relay controls frequently failed and shut down the machine. As a result, a minimum of two or three molding machines were always out of service in the plant, which raised expenses. This also made it difficult to meet customer delivery requirements. Manchester Plastics decided to upgrade the control system of one of the machines which was causing problems with a Scoremaster EL controller from Solid Controls, Inc., Hopkins, Minnesota. This controller soon demonstrated diagnostics capabilities superior to the others in the shop. The system makes it possible for the operators to view process parameters, including set up data and actual data, clearly and concisely. By looking at the screen, the operator can see each step in the process: the output board tells the clamp to close, the input board signals clamp closed, the output board moves the injector forward, the input board signals no response. These diagnostics features make it possible to quickly isolate a problem and determine which part of the machine it is coming from. In the example above, the problem was pinpointed as the solenoid driving the injector or the connecting wiring. It then becomes a simple task for maintenance to fix. Based on the success of this single control, over a period of several years, Manchester Plastics upgraded every control in its plant to either Scoremaster EL or System 10 (Trailblazer) models from Solid Controls. The result has been a drastic reduction in downtime throughout the plant. Several machines have not had one minute of unscheduled downtime since the new controls were installed. Another advantage of the new controls is that they can easily be reprogrammed to add capabilities to the molding machine. For example, several machines have been reprogrammed so that the mold is opened while the screw is rotating to decrease cycle time. Thin walled parts produced for the automobile industry have a faster than normal cure time. Adding a shut off nozzle makes it possible to take advantage of this faster cure time by opening the mold and removing the part while the screw is still rotating. The equipment needed to activate a second set of cores was added to another machine. With the old controllers, the logic required to implement these changes would have been very difficult to install. A factory service person would have had to come to the plant for two days to rewire the controls, which would have been very expensive. All that is required with the new control is ordering a new EPROM chip and plugging it in, which takes only a few minutes. The new controllers automate statistical process control (SPC) data collection, thus eliminating the need for manual data collection. Manchester Plastics now maintains records on all important molding parameters such as injection pressure, barrel temperature, velocity profile, etc. The controllers are capable of tracking both internal and external process parameters and producing X-bar and R graphs. The documentation is also an important first step towards ISO 9000 certification, which the company plans to achieve within a few years. After helping factory service people install controls on several machines, Manchester Plastics maintenance staff said they could do the job themselves and have ever since. This has provided additional cost savings. It generally takes one person about 10 days to install a control. Overall, the plant has been extremely happy with the new controls and intends to use them on all future machines in the plant. The plant has also recommended them to other Manchester Plastics plants and several of them have begun to standardize on the new controls as well. -David Ross is Facilities Superintendent at Manchester Plastics, Manchester, Michigan. Solid Controls, Inc., 820 South 5th St., Hopkins, MN 55343 USA Phone: 800-899-5586 Fax: 952-933-8961 E-mail: info@solidcontrols.com Copyright © 2001, Vert Tech LLC. All rights reserved.