Automation: Think Outside the Work Cell

Delphi’s new molding facility in Vienna, OH, makes maximum use of automation to take errors and manual labor out of the injection molding process. It has achieved a pinnacle of automated manufacturing, with as few as 8 machine operators for a plant of 120 molding machines. That works out to one operator per 15 machines.

The plant produces about 387 different parts, for a total of about 1.4 billion parts per year. The US$58-million facility is part of the Delphi Connection Systems business unit. It supplies plastic connector housings and related parts to the automotive, computer, telecom, aviation, medical and military markets.

The Vienna plant demonstrates some groundbreaking thinking about the molding process and how to organize and manage it.

“At the old plant, we took care of quality problems on a part-to-part basis,” explains Gregory Pachol, project manager. “For these two new plants (Vienna and Cortland, OH), we stepped back from the problems, and used a lot of involvement from the people in the plant.

“We set out to put solutions in place to prevent errors.”

Those solutions include “e-manufacturing” systems: the Microsoft.NET software and platform, combined with an Ethernet network and GE’s Cimplicity manufacturing information system. This advanced IT structure enables real-time monitoring of order entries, material needs, tooling changeovers, production runs and direct-ship labelling.

Handling parts can be automated

“We modeled the entire operation to determine bottlenecks,” explains Pachol. “We found that a lot of time was spent on container handling.” So that process was automated. Under-press conveyors separate bad parts from good, based on process monitoring by the machine control.

Good parts are conveyed into a shipping container placed by an automated guided vehicle (AGV).

The containers are filled by the conveyor, sealed and labeled at the machine by an operator, and then picked up by an AGV. The AGVs, supplied by Frog Navigation Systems, follow a magnetic grid set in the floor, and receive data input by wireless communication.

The AGVs off-load containers at a series of conveyors which direct them to either pallets for direct shipping or to a storage area for inventory. More than half of this plant’s production is packed, labeled and direct-shipped to the customer right from the press.

Materials handling can be automated

An integrated materials handling system supplied by Novatec conveys, blends and dries more than 90 different compounds. Raw materials are centralized in two rooms. There’s one attendant per room.

Bulk compounds are delivered in sealed aluminum returnable bins (rather than gaylords) from a Delphi compounding facility. The metal bins are a proprietary airtight design, so there is no contamination by debris or moisture. A central materials handling system conveys material from these bins to blenders and dryers which are grouped together in one area of the production floor. From there, an innovative vertical valve stack actuated by I/Os can send any material to any injection press. Each press has a single incoming material line to a just-in-time receiver.

For lower-volume materials, portable bins are wheeled to press-side, and can be hooked up to a portable loader/dryer combination. The portable conveying/drying units communicate with the molding machines via the Ethernet network, and the bins are equipped with a level sensor to alert operators when a change is needed.

Scrap parts can be reground at press-side, but the regrind is conveyed back to the materials handling room where it is sifted to remove fines and longs before being mixed back in with virgin material at a specified rate. This achieves consistent material quality to ensure minimal process variability.

Consistency is king in an automated environment

The decision to use only all-electric machines reduced capital costs for the project, and produces on-going savings through reduced energy consumption and less waste. Delphi’s one-time savings amounted to more than US$1.7 million due to downsized utility infrastructure, less need for machine cooling and other mechanical changes. Annual operating savings are gained by a 55% reduction in energy consumption, and sharply reduced tool cleaning costs.

Delphi chose Milacron to supply 124 all-electric injection molding machines. The units are all Roboshot models, either 55, 110 or 165 ton. Pachol believes the all-electric machines are more quiet and more compact than hydraulics. As well, they are able to perform simultaneous functions to decrease cycle time, such as overlapping the metering, clamp open and ejection phases. The company estimates the electric presses deliver 15% higher throughput than similar hydraulic presses.

The molding machines were modified with a unique control to be compatible with the facility’s GE Cimplicity manufacturing system. In addition, each machine has its own Ethernet hub and I/O rack for interface to auxiliary equipment, such as granulators, loaders, pickers and AGVs.

To ensure that each machine is set to proper and optimal parameters for each job, Delphi engineers use the four laboratory presses to optimize process parameters for each tool before it goes out on the floor. The settings are then recorded in a central database, not at a particular machine control. When the tool goes into production, the machine control accesses the optimal settings from this central repository, ensuring it has the most up-to-date settings and documentation.

Another policy that contributes to process consistency is the “no blocked cavities” rule. Blocking off one under-performing cavity to keep a multi-cavity tool in operation is not permitted, says Marco Popovitch, general supervisor, plastic molding. “We have a zero-bolcked-cavity policy. If one cavity has a problem, we correct it immediately, so we have the same process running consistently.”

The Vienna plant also adheres to strict machine and tooling maintenance schedules.

While it may seem Delphi Vienna has achieved the peak of automated manufacturing, they are still open to ideas for improvement, which guarantees they’ll stay at the top.