Think Plastics Webster Plastics molds a niche replacing historically metal parts with leading-edge composites.
ByDavid Drickhamer Webster Plastics, Fairport, N.Y.
At a GlanceWeb-Exclusive Best Practices ByDavid Drickhamer Benchmarking contact: Alan Gross, director of operations,
[email protected], 716/425-7000
Process Monitoring Drives Technical Expertise Since 1990 Webster Plastics, Fairport, N.Y., has been using a dashboard-type production monitoring system to track its injection-molding processes. This system, known as MATTEC, is core to the company's ability to successfully mold the highly engineered composites that are its specialty. "Without a good process-monitoring program, you don't have the repeatability that's essential for injection molding," says Joe Buonocore, plant manager. Over time, Webster's process-monitoring system has become increasingly sophisticated. During the first phase of implementation, the company equipped all of its machines with independent monitoring devices, such as thermocouples, external pressure transducers and linear potentiometers. These instruments were installed in addition to the machines' built-in measurement devices. Webster Plastics engineers and technicians can now test and verify that a machine's capabilities are within specifications. Tracking 13 process parameters for every shot, the system converts statistical data into live process control graphs that the workcell team can easily monitor in order to maintain optimum quality and efficiency levels. The system also collects data on raw materials used, color blends, quantities, tool usage, and job start and completion times. In the second and third phases of implementation, manufacturing engineers established limits and then optimized the process parameters using designed experiments. This scientific approach required a change of culture because it removed some of the "art" from the process technicians' jobs. They had to become comfortable setting the 13 parameters for each job and walking away with enough faith that it would run properly. "If things go out of spec," notes John Doucette, process engineer, "we are immediately notified." An strobe light starts flashing and the suspect parts are automatically diverted to a different bin. Beyond optimizing the production flow and improving traceability, this process information has other uses as well. Armed with relevant data showing tool wear, it's easier to sell customers when their tools need to be refurbished or replaced. It's also possible to use the SPC data as a quality assurance tool, completely eliminating dimensional checks "We draw correlations between process parameters and dimensional results through DOEs," comments Alan Gross, director of operations. "Presenting that data as a package to the customer will convince them, in some cases, that we don't have to do dimensional checks any more. It saves us money; it saves them money. But it's still too much of a leap of faith for many customers."
Maintenance Fanatics The sophisticated process-monitoring system at Webster Plastics wouldn't be half as effective without a commitment to fix machine problems before they crop up, whether or not they are having an immediate impact on product quality. This required a change in mindset on the part of maintenance personnel. Looking at it purely from a throughput perspective, like many manufacturers the maintenance department used to try to eke out as many parts as possible from a set of tools or a machine before shutting it down for repair. Today, they will stop the machine at the first sign of trouble and fix the problem. If a critical part or component is overly worn-even some expensive parts such as the machine barrel or the screw in the barrel that heats, mixes and injects the plastic, which could conceivably run for a few more hours, or even weeks-it is replaced. As a matter of policy, plant managers say they won't turn off a cavitation (an individual cavity in a multi-part tool) or run a machine at a slower rate to meet quality requirements. "We talk about maintenance in three ways. One, reactive, or problem related; you have a problem and you solve it. The other is preventative, where you anticipate problems and that's where process monitoring comes into play," says Alan Gross, director of operations. Much of the tool maintenance done at Webster Plastics, when the tools are disassembled, cleaned, retouched, coated and plated, falls into the preventative maintenance category. At any given time one machine in each workcell is shut down for preventive work. The third facet of Webster's maintenance program is predictive. "Predictive maintenance is really where the future is," Gross predicts. "That's being able to-based on the data you've collected-alter your PM [preventative maintenance] schedule to minimize any downtime. It also reduces your direct costs because you're doing PM when PM needs to be done, as opposed to an arbitrary schedule or when the machine manufacture recommends." All of this effort to maintain repeatability and product quality is aided by the fact that Webster Plastic's injection molding machines are only 5 years old on average. Company managers say they are moving toward all-electric models, which currently account for only two of their 46 injection-molding machines, because the servo-motor driven equipment reportedly offers higher repeatability and fewer maintenance requirements. Although such a proactive maintenance and equipment program requires more investment on the front end, it has delivered measurable cost savings and has won over the most doubtful observers. "I was extremely skeptical about this," recalls Stephen Wheeler, quality manager, "but our scrap numbers are becoming invisible."
Centralized Material Handling Unusual for a custom injection molder of its size, Webster Plastics invested in a semi-automatic, centralized material feed system when it moved to a new building in 1998. The closed-loop system features ten miles of piping and plays a critical part in the company's ability to mold 650 active part numbers from 350 different resins with minimal waste. Specializing in highly engineered composites, approximately one-third of Webster Plastics' total costs is raw materials. One operator manages the whole process, making sure the appropriate resins are mixed, dried, and delivered through flexible pipe that runs octopus-like to the 46 injection-molding machines in the production area. The resins must be dried because they are hygroscopic, absorbing water from ambient air, and need to be brought to the proper moisture level prior to molding. Runners and some scrap is reground and sucked back to the central system where the material is filtered and metered into the raw material flow at specified proportions. The flexibility of the material-handling system supports the molding operations' need for rapid machine changeovers. Indeed, material handling is one of several disciplines -- including the toolroom, set-up, processors, inspectors and operators -- that Webster Plastics has successfully orchestrated to reduce set-up times. In combination with such technologies as hydraulic clamping, mold carts, quick disconnect hardware and other tools, they have cut changeover times from 225 minutes to 15 minutes on average. That's especially impressive considering the broad range of materials used by Webster Plastics. It's not just a matter of changing dies; all of the material handling equipment also has to be purged. "It's especially difficult when you're going from light materials to dark materials because one pellet that's left over in this ten miles of pipe could conceivably contaminate a lot of parts. That's one of the more obvious challenges," notes Alan Gross, director of operations. "Even with small batches, if you contaminate polypropylene with polystyrene for example, you would get a very brittle part. You couldn't see the difference but it could be a catastrophic failure in the field. That's why it's so important that the lines are cleaned out and that it's verified at the machine and back at the material control system."
Overcoming The Cultural Barrier To Empowerment Like many of the improvements at Webster Plastics, the establishment of an empowered work culture was a slow process that demanded a long-term commitment. When they began the transition to work cells in the early 1990s, company president Vern Dewitt recalls that he mistakenly assumed that everyone would want more responsibility and authority. That wasn't the case, and the benefits of the non-traditional work structure really only took hold with natural attrition, as people who didn't fit the new organization left for other companies and the company hired people who were comfortable with increased responsibility. "It's contrary to everything people have been taught," he says, blaming the American education system. School is about rules, and doing what you're told. The desire for "authority and responsibility comes from your parents. You either accept it or reject it. A lot of people don't want it. They don't see the advantage, what's in it for me." Today, three-person teams on each shift-comprised of a quality technician, molding technician, and material handling specialist-manage Webster Plastics' three workcells. They conduct their own training, cover for downtime, schedule jobs, and oversee various continuous-improvement projects. Through the process-monitoring system, they also have access to real-time information on every aspect of the manufacturing operation. "If they're really excited about their jobs, the more information you give somebody, the better," Dewitt notes. One of his key objectives, critical to maintaining the company's flexibility and responsiveness, was to streamline the information flow between the plant floor and material suppliers and customers. "There's no value added in having a supervisor around," he adds. A supervisor is just another layer that customers have to go through to get an answer or decision.
- Plant size: 75,000 square feet
- Start-up date: 1954 (new facility 1998)
- Special Achievements
- 1996, 1997 Most Innovative Use of Plastics Award, Society of Plastics Engineers.
- IIIE/NIST Outstanding Achievement Award for Successful Lean Manufacturing.
