/ Catalog / Testimonials Electronic Parts Molder Cuts Scrap 50% After SCI Trailblazer Upgrade Item 2 of 6 By Jim Petosky, Plant Engineer, Moldamatic, Inc. PENNDEL, PENNSYLVANIA-Moldamatic has cut the scrap rate on typical parts by 50% by upgrading older machines to closed loop controllers that automatically adjust injection pressure in response to molding conditions. The new controllers reduce scrap by sensing machine faults such as a solenoid failure and stopping the press after only a single bad part is produced. Productivity is higher because the new controllers drastically cut set-up time and reduce shop floor downtime 20% by quickly pinpointing molding problems. Moldamatic is a custom injection molding house that produces a wide range of components for many different industries. The company's largest single market is the electronics industry for which it makes printer cartridge cases, edge connectors for circuit boards, input/output connectors and many other parts. The company uses Van Dorn presses nearly exclusively. Examples of machines used by the company are two, eight and ten year old, 75 ton Van Dorn molding machines with 5 ounce barrels. These machines were originally equipped with open loop controllers that had no way to verify that their commands were actually being carried out as intended. This made it difficult to handle parts with tight dimensions or other critical features that require a very tight processing window to maintain quality standards. They were also highly dependent upon electro-mechanical devices such as relays and limit switches that would frequently malfunction without any warning. Management considered purchasing new machines but questioned whether the high cost was justified since their basic mechanical functionality was excellent. So, they decided to upgrade the control systems on the machine with Trailblazer (System 10T) closed-loop controllers from Solid Controls, Inc. (SCI), Hopkins, Minnesota. At the same time, mechanical systems on the presses were improved by rebuilding cylinders, and repinning and rebushing the toggle linkages. Hydraulic systems were overhauled including replacing valves where necessary. The Trailblazer controllers they selected provide the important advantage of being able to keep all molding variables under close surveillance. The controllers can be programmed to issue an alarm or even shut off the machine if process parameters fall outside control limits. They also offer digital set up of all molding parameters, thus avoiding the problems that were previously experienced with the failure of electromechanical components. The diagnostic information provided by the controllers normally pinpoints the problem, which eliminates troubleshooting. Closed loop position control makes it possible to maintain screw travel within hundredths of an inch as compared to the fraction of an inch accuracy possible with the old open loop controls. The improved repeatability virtually eliminates the possibility of overpacking or short shots which can produce significant damage to the mold. Clamping repeatability has also been improved to hundredths of an inch. This makes it possible to set low pressure closings more accurately, further reducing the risk of damage to the tool. The Trailblazer also accurately controls barrel temperature on a multizone basis. For example, suppose the mold loses clamping pressure. The injection screw will rush forward and the mold will flash, thus spoiling the part. In the past, it was possible to produce hundreds of bad parts before an operator noticed the problem. Now the controller will detect this problem by monitoring the injection velocity profile and shut down the machine, usually after only one piece of scrap is produced. Set up time has also been substantially reduced. The old controllers relied on a number of manual settings such as thumbwheels and limit switches and there was no way to be sure they were right except to start the machine. This process typically took about two hours each time the machine had to be set up. The new controllers take only an hour to set up the first time for a new mold because parameters can be entered onto the keyboard directly from the set up sheet. A bit of trial and error is normally required to get it running right the first time. The whole process takes about one hour. After the mold is running right, the configuration is saved into the controller's memory and it can be recalled at any time in the future to produce perfect parts in about a minute. Besides stopping the machine, the controller also includes diagnostic tools that help maintenance staff identify the problem. When the power is turned on, the controller checks itself as well as key machine functions such as solenoid valves. If a fault occurs, the controller issues a code that provides the location of the problem as well as a graphical depiction of the machine with the fault highlighted. With the problem immediately identified, maintenance can immediately begin work on solving it. In the past, it typically took an hour or two just to locate the source of a machine problem. The new controls are considerably simpler than older solid state controllers. They have only 12 screens and these screens are arranged in a very logical manner. For example, with a single keystroke the user can jump from the clamp screen to the injection screen or vice versa. It normally takes only about 15 minutes to explain all of their functionality to a new operator. All in all, switching to the new controllers has dramatically improved quality and productivity at Moldamatic. 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.