Assembly in Action / Medical Devices Assembly / Plastics Assembly

Cap Maker, Welding Supplier Combine to Lock in Drug Safety

More than 30 years after the Tylenol tampering case—in which seven people died in Chicago and surrounding suburbs—prescription drug safety remains critically important and an ongoing challenge for pharmaceutical manufacturers. The Tylenol case prompted the development of tamper-evident safety features on bottles and packages, and push-and-turn caps on prescription canisters.

In 2011, Cap-N-Lock LLC introduced the industry’s first combination cap for canisters called The Locking Cap. Made of lightweight ABS plastic, the cap is designed to be completely childproof, provide maximum protection against teen pre-scription use and be senior-friendly.

The cap has four dials users must turn to match a preset combination that allows the cap to be twisted and removed. Up to 10,000 combinations are possible.

Joseph Simpson, president of Cap-N-Lock, developed the cap in reaction to his younger brother Steven’s addiction to prescription medication. He worked closely with Dukane Corp. to develop The Locking Cap. Dukane provided feasibility studies and product-design assistance before developing an ultrasonic welding system for welding the cap together.

Henry Plastics injection-molds the cap’s eight components and sends them to Cap-N-Lock, which assembles the caps. Cap-N-Lock also produces two Locking Cap adapters that fit a wide range of the most common prescription bottles.

The welding system includes Dukane’s iQ series servo welder press and a custom horn and holding fixture. The press system offers dynamic servo motion control, robust mount construction, data acquisition, and reliable calibration and validation.

“The speed, accuracy and precision of the welding process are critical to the production of the cap,” says Simpson. “The weld needs to be perfect every time to ensure a high level of quality control.”

During assembly, the locking mechanism (containing the four dials), a tension plate and a twist-on piece are welded together to make The Locking Cap. A lower housing ring is then welded to the canister to complete the assembly.

An electric system, the iQ press performs repeatable and reliable welding. The system’s dynamic servo technology de-livers precise control of ultrasonic stack velocity, force and location. Dynamic velocity melt initiation allows velocity and force control of sonic energy during welding.

The system’s Melt Match mode enables Cap-N-Lock to match the velocity of the ultrasonic stack with the melt flow ve-locity of ABS plastic. This technology ensures optimum molecular intermingling, while producing strong and reliable welds.

The Locking Cap is sold as an aftermarket product for about $10 at Save Mart, Ralph’s supermarkets on the West Coast and other pharmacies.

For more information on ultrasonic welding systems, call 630-797-4900 or visit

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