Deployment of Robots Within Insert Molding Workcells Results in Dramatic Improvements

Every year products are being made smaller and smaller and tolerances become tighter and tighter. And when you add the need to meet strict safety-code requirements, it becomes a formula for finding new ways to do business.

Molding International and Engineering Inc. is a custom insert molding specialist in Temecula, Calif., that serves the automotive, telecommunications, electronics and medical industries. Applications include high-precision insert molded components incorporating metal terminals and lead frames in material thickness ranging from .005 to .032 inches.

In producing insert molded connector housings for safety-critical automotive applications, MIE needed a better way to load precision stamped terminal pins into the injection mold cavities. Of critical concern was consistency of insert placement to minimize potential for mold and insert damage. The company also had to meet difficult molding cycles, offer high placement tolerance of components, conduct 100% inspection and eliminate failure modes associated with manual operations.

The solution was to introduce robotic workcells into the manufacturing process. MIE selected DENSO Robotics’ six-axis VM 1000 units, which are used in an insert molding workcell and interface directly with the molding press. This was the first time MIE had used flexible automation as part of its insert molding strategy. ‘‘The nature of the business was to continue with time-tested manufacturing processes, using custom automation on a limited basis, being designed around specific insert molded components,’‘ said David Hart, MIE’s engineering manager.

MIE had seen other companies invest in product-specific automated systems only to be caught with surplus machinery at the end of the production run, which tied up valuable working capital once runs were completed.

‘‘The new DENSO robots offer a wide range of usage flexibility in programming for current projects and for those in the future, so companies like ours will have options on how to expand and leverage the investment by integrating robotics as part of an overall flexible automation strategy,’‘ Hart said. ‘‘The robots can be adapted to satisfy a wide variety of manufacturing challenges that are unique to insert molding. That was the key reason to go with all six-axis units. We wanted long-term flexibility for years to come.’‘

The first job in which MIE deployed its flexible automation strategy was in the manufacture of an insert molded connector housing, which used terminal pins having a 0.008-inch lead thickness. The traditional manual loading of the inserts was not practical, in terms of both quality and cycle time.

From this first application, the company has leveraged the flexibility of the six-axis robotic workcell into the manufacturing strategy of nearly every insert molded part evaluated for production at MIE. In the manufacture of insert molded connector housings, used for holding accelerometers in airbag deployment systems, MIE noted a significant improvement in part cleanliness, dimensional consistency and in-process yields. Failure modes normally associated with a manual process are now nonexistent with robotics in place. ‘‘The insert molded products manufactured at MIE today are so rigid in their quality requirements that our best existing processes could not consistently meet the standards,’‘ Hart said.

Installing robotic workcells had multiple impacts on MIE’s business. It reduced the labor content required in each process and it reduced operator-related failure modes. In addition, molding process consistency was greatly improved because of a significant reduction in shot-to-shot cycle-time variation that is achieved when using a robot to load and unload the injection mold. With the use of DENSO robots, MIE also realized a significant reduction in small particulates generated when the soft tin plating common on connector terminals comes in contact with the hardened mold steel cavity, during the manual loading and unloading of an injection mold.

‘‘We were very surprised at seeing how much cleaner our processes have become as a result of deploying the DENSO robots to more accurately perform insert loading tasks,’‘ said Stephen Hughes, director of sales and marketing. ‘‘MIE customers demand insert molded connectors free of imbedded metal particulate, which we are now able to produce using DENSO robots to load our inserts.’‘

Since deploying DENSO robots in its insert molding workcells, MIE has seen dramatic improvements in quality, increases in volume and a reduction of PPM defects by more than 150 percent. There are a reduced number of failure modes and a more consistent molding cycle. The production lines are now achieving more hours of operation with less personnel and overall increase in plant utilization. Employee health and safety was another factor in the final decision to use DENSO robots. The risk of exposing MIE employees to repetitive-motion injuries is now minimized even further, allowing staff to focus their energies on continuous process improvements and innovative valued-added customer strategies.