Build it and they will come: How the Tech Group tailors the job to fit the machine

Most injection molding is akin to eating at a cafeteria. Molders are typically handed a part or a mold, and then asked to devise a molding process to accommodate it: a press here, a dryer there, a robot here, a conveyor there. If you throw insert molding or overmolding into the equation, customization then becomes trickier and more expensive.
     Several years ago Scottsdale, AZ-based molder The Tech Group was in just such a conundrum: How do you design specialized molding cells without requiring excessive capital up front? Tom Podesta, vice president for marketing and sales of consumer products found the answer. Don't build a customized work cell for each customer; design one and modify the job to fit the molding cell. "We decided to not go down the path of fitting a machine for a job," Podesta says. "With life cycles getting shorter and shorter, it's important to have flexible work centers that can easily be converted to new applications as dictated by our customers' needs."

Keep it Simple
The flagship of this concept is a vertical insert molding work cell The Tech Group designed for an insert-molded needle assembly (Figure 1). The press is a 125-ton Newbury with a three-station rotary shuttle. Two Fanuc LR Mate robots handle all of the inserts and parts. The pin inserts, .5 inch long and 1 mm in diameter, are sorted and presented to the first robot, which places eight in each mold. The second robot degates and pulls the finished parts and transfers them to separator chutes.
     While this setup may seem somewhat ordinary as far as insert molding and automation are concerned, for The Tech Group, this is as specialized as it will get in order to keep things flexible. For subsequent customers who need a part insert molded to tight tolerances, the work cell will look remarkably similar. "The beauty of it," says vice president Jeff Goble, "is that this work cell can service several different customers. When we have to change over, all we have to do is change the end-of-arm tooling and the part handling, switch out the tooling, and we're set to go."
     In fact, the 125-ton press may be a tad large for future applications, but by standardizing on a 125-ton press The Tech Group can meet the needs of most jobs. By standardizing on one set of machinery for every insert molding job, The Tech Group reduces operating costs and puts the process within reach of many more customers. "The future is in automation, in reducing manual labor. We are not a manual loading molder," Goble says. "We adjust the job to fit this standard setup. We adjust cavitation, we adjust mold layout-within reason-to fit the cell."
     The Newbury molding cell produces 30,000 parts a day. The Tech Group is currently duplicating this cell on three additional programs and soon will install a system that senses absent pins and automatically discards the affected part.

Two Materials, Two Presses
The flexibility built into The Tech Group's automated insert molding cell is carried through on its two-material overmolding jobs as well. The best example of this process is the work cell used to mold a two-component cartridge. The part consists of a square frame about 3 by 3 inches molded from a 30 percent glass-filled polyphenylene oxide (PPO). Overmolded along the inside edge of the PPO frame is an opaque PP with a tolerance of ±.001 inch.

     The Tech Group uses two injection molding machines side by side running with almost identical cycles to mold the part (Figure 2, p. 76). A high-speed robot between the presses pulls PPO parts from the eight-cavity press in the first machine and transfers them to the second press, where the PP is overmolded. Finished parts are pulled by the same robot and transferred to separator chutes.
     The strategy here is to employ standard, single-barrel horizontal presses whenever possible. Although a two-barrel press might seem ideal for the job, the flexibility of the two-press configuration means the machines can be more easily adapted to other cells in the future. It also means the job did not dictate a huge outlay of capital on a two-barrel press. Again, the process is adjusted to fit the configuration. And by standardizing on one configuration, costs are reduced. "Our customers are really excited to find a solution that's cost-effective, that allows them to combine materials," Goble says.
     The company has duplicated this cell several times already and shipped it to other Tech Group locations throughout the world for production. Every work cell assembled at The Tech Group is engineered and qualified first in Phoenix before it's shipped to the production site: Singapore, Ireland, Guadalajara, Oregon, or one of the company's local sites in Phoenix. The Tech Group also sources its equipment from just a few suppliers, namely Conair for auxiliaries, Van Dorn Demag, Netstal, and Cincinnati Milacron for its presses, and Zeiss and OGP for quality control work.