Technology Notebook: Automation can keep U.S. molders competitive in world markets

The demands of producing medical goods, ones that comply with Federal Class IV standards, are well known in the molding industry. Legendary quality standards and rigorous documentation and testing are accepted practices in this segment of the injection molding marketplace. Molders have created tools for the health services field that are highly effective. Good examples of injection molded plastics products commonly used in hospitals include suture guns or syringes, both used in direct patient care applications.

Typically molded using virgin resins, parts such as those just noted demand tight tolerances and specific labeling to show volume and to comply with the legal obligations a processor has to meet when producing these parts.

A molding workcell is able to mold, remove the part from the mold, degate and deflash it, and decorate or weld it well within the 10- to 16-second cycle time parameters common in this industry segment. Moreover, a processor can ensure that quality standards and the related, necessary documentation is met because the integrated vision system can measure the accuracy of the part to within hundredths of a millimeter and document it, as well. In fact, in most instances the limiter with these workcells is the molding machine cycle time, as the automated function happens well within the parameters of the cycle.

Cutthroat Car Biz

Any supplier to any automotive OEM will tell you that efficiencies are critical not to just gaining business, but also to holding on to existing business. In the cutthroat world of automotive OEM suppliers, workcell systems are gaining hold, particularly when a processor is molding ?under the hood? or interior automotive parts. In the example of a molded interior part or trim component, the workcell would operate in the following manner:

The press molds the parts, and the robotic arm retrieves and ejects the parts from the mold. Degating, deflashing and clip-insertion functions are preformed, typically using a 6-axis articulated arm robot to flexibly maneuver a part to the secondary operation phase of manufacturing. In a fully automated workcell, metal clips or other fasteners are inserted into the part, making the molded part ready for installation into the automobile. The part is then off-loaded onto a belt conveyor adjacent to the press, and sent to the OEM for final installation.

Other examples of an automotive part that is rapidly being produced in automated workcells are instrument clusters or shrouds. From molding to decorating, and in some operations for full component assembly, parts are being molded and made ready for final installation into the vehicle with beside-the-press automation systems. The part is touched only once, but as many as four steps have been completed during the manufacturing process.

Keeping a Lid on It

The packaging marketplace is a hotbed of competition for the North American molder, who must exhibit a technological as well as geographical edge to land and keep what can be a very lucrative business. More and more, however, the OEM wants something different, even unique, that will pique a jaundiced customer?s eye. Oftentimes the eyecatching variation is found in the form of unusual packaging, whereby new plastic technologies and bold colors and graphics are used to hold a customer?s interest. In the packaging market, the ability to mold and decorate in one seamless operation can be the key to both technical and commercial success.

Why handle parts more than once? In at least one case, a processor made a label with more graphic impact with an inmold labeling (IML) workcell. The label smoothly integrates itself within a molded plastic lid, for a seamless appearance that shows off bold colors, imparting a nearly artistic quality to the part. Within a 20-week timeframe, an inmold labeling system was designed and built that gave the customer a higher quality part, with the ability to run continuous quality control functions, reduced work-in-progress, handled changeover better, offered the flexibility to adhere labels to various container sizes and shapes, and packaged the end parts for shipping, with no secondary operation.

In this way, up to five steps are reduced into one operation, reducing work-in-progress substantially by conducting all these steps within a 4- to 8-second cycle time of the molding press. These IML robotic workcells extend the benefits of quality and repeatability to molders making precise, decorated parts to meet large production demands. Placing a high-speed side entry robot into the molding area, and relying on vision systems to ensure quality and accuracy, can manage the entire molding and automated functions. Further, it is monitored by a single controller, with superior and repeatable results.

Going Vertical

Molders are increasingly using vertical clamping injection molding machines as the most reliable and cost effective way to mold plastics with metal inserts. Metal inserts are loaded into mold cavities by means of a gantry or a six-axis robot, providing accurate and fast placement of the inserts with a consistency unattainable with a human operator.

Many cells are equipped with a shuttle or rotary table, which allows for the concurrent loading of inserts and the unloading of finished parts, plus actually molding the part in the first place. Integrated machine vision systems check for the appropriate and complete placement of the inserts, thus avoiding damaging the tools and increasing the parts yield rates. While the molder must invest in additional lower mold halves and automation to make this possible, a return on investment is typically achieved within 6 months, when the molder utilizes a two-shift operation. In addition to the labor savings, the greatest cost savings are realized with greatly reduced mold damage and much higher yields. Well-designed vertical press automation systems can handle different inserts and process different parts, simultaneously, reducing the return-on-investment period even more dramatically in most cases.

Taking Advantage

North American molders are met with business challenges coming from all over the world. But they hold major advantages over competitors in that geography?the ability to quickly respond to time-to-market demands, and communicating in the same language and currency are all formidable tools.

By looking and going beyond simply ?shooting and shipping,? molders with workcell final assembly of a molded part have a definite edge to compete and be more profitable.

With today?s systems, molders can go from mold debugging to Six Sigma quality results in shorter times than ever thought possible, with inspection scores for acceptable parts yields as high as 99.99%.

As the global economy gets more vigorous, North American molders must maintain their quality and technological advantage, and workcells have shown themselves to be one of the tools that can help keep molding programs in North America.