Reducing packaging time of surgical saw blades—safely

Pharmaceutical & Medical Packaging News staff

A new system makes changing heat blocks for blister sealing safer, while improving heat transfer and sealing-time efficiency.

Synvasive Technology Inc. (El Dorado Hills, CA) has carved out a niche in the medical device market by making surgical-steel saw blades for orthopedic surgeons to use when reconstructing bones and preparing joints for implants. Synvasive’s blades include a patented tooth design known as Stablecut, which is intended to cut more accurately and more coolly than competitive blades.

Synvasive packages the blades using a new Aergo 2 Plus sealing machine from SCA Consumer Packaging (DeKalb, IL; formerly Alloyd Co.). Operators at the machine’s two stations place blades into secure, easy-to-open trays at the rate of 16 per cycle.

According to Allen Culuris, manufacturing process engineer at Synvasive, the company ordered the new Aergo 2 Plus because increased demand was requiring more packaging capacity. The new Aergo 2 Plus is now the primary sealer.

The Aergo 2 Plus medical tray sealer is the latest version of SCA Consumer Packaging’s ergonomic line of medical tray and retail blister sealing machines, incorporating design changes intended to make operation less stressful for both operators and trays. The unit is a front-to-back shuttle sealer that includes two load-and-unload stations, each with a shuttle-bed apparatus to slide the trays under the press-and-seal station located in the center of the machine. Depending on workload, either one or two operators can load trays, products, and lid stock, in that order, into cutout areas in the nesting tray that rides on the shuttle apparatus. Because the machine’s operation is largely based on the operator’s pace, any ergonomic enhancements can increase productivity.

Improvements incorporated in the newer Aergo 2 Plus have made the shuttle smoother and ergonomically easier on operators’ hands. The table is 40 in. high—a height recommended by industrial designers for maximum comfort—and a footrest has been added.

The newer sealer also features SCA Consumer Packaging’s patented ATEX (automatic heat-plate tool exchange) system for changing heat plates during package changeovers. The system enables operators to change hot (up to 500°F) and heavy (up to 12 lb) heat plates safely and more easily, without having to call for additional help.

Heat plates are changed using transfer trays. The operator places an empty tray on the shuttle bed and then turns the ATEX system key to the “unlock” position. The Aergo 2 Plus automatically lowers the hot heat plate onto the tray and releases the positioning cones that keep it aligned. The operator then moves the tray to a holding cart and positions another tray holding the new heat plate on the shuttle bed. The ATEX key is turned to the “load” position, and the Aergo 2 Plus automatically activates clamps that grip and hold the positioning cones, securing the heat plate in position. The connection is positive, and alignment is perfect each time.

“The ATEX system really cuts changeover time,” says Culuris. “We now change over in 25% of the time it took on the older system without ATEX.”

While SCA engineers were developing the patented ATEX system, they also studied the transfer of heat from the machine’s heat platen to the heat block that does the sealing. The heat block is a custom-machined tool, the contour of which perfectly matches the geometry of the tray flange to which the package lid is to be sealed, focusing heat and pressure during the sealing process to the precise points on the package where they are most needed.

What the engineers found was that, because the ATEX system seats the heat block to the machine’s platen perfectly each time and locks it in place securely at three points, heat transfer between the two parts meets less resistance than it does in machines where the installation is done by hand.

In practical terms, the increased heat reaching the blister means less dwell time is required for each seal, increasing the number of blisters that can be sealed per hour.

“Our study showed an increase in transferred temperature of 4%,” says Ken Sullivan, director of marketing for SCA Packaging. “Small as that seems, it was enough to increase the productivity of the machine we studied by one cycle per minute. That amount of increase adds up very quickly.”

For Synvasive, the new Aergo 2 Plus with ATEX produces approximately 32 blisters per minute, while the older SCA sealer that the company had used delivered about 18. When time needed to load and unload twice as many blisters and blades per cycle is taken into account, the gain is significant.

The newer heat blocks also feature an Alloyd Armor coating, a codeposit of Teflon and electroless nickel to separate the block from the blister tray. Earlier blocks used a Teflon-impregnated fiberglass membrane that could be a source of contaminating particulates and had to be replaced when it wore with use.

“These coated blocks have yielded more-consistent seals and better process capability (Cpk),” says Culuris.

SCA Packaging also aimed to make machine validation less time-consuming. A validation port on the Aergo 2 Plus enables Culuris to continuously check the time, temperature, and pressure settings of the sealer while it is running, letting him keep a running record of those numbers.

“I attached a data logger to the port,” he says, “which collects temperature data every 2 seconds and continuously charts dwell time and air- pressure figures. Since it went into operation, temperature in the Aergo 2 Plus heat platen has varied only about 3°F, which is acceptable.”

Synvasive’s Aergo 2 Plus was validated and placed in production in June 2006. As new tools and heat blocks are delivered, Culuris needs only to run a few hundred blisters from each one to demonstrate that they work as described. Then they, too, can play their role in streamlining the company’s production schedule.