Innovations in batching, dosing and weighing

David Chappell, who works for Proctor & Gamble (P&G), responded to our question with questions of his own. “Is it better to implement all the batch addition control functions in the process automation system (PAS) software,” he asks, “even if you have to compromise the control algorithm? Or, is it better to integrate best-in-class, standalone instruments and devices with the PAS?”

Chappell explains that, several years ago, P&G engineers developed a predictive adaptive control (PAC) algorithm that dramatically improved P&G’s ability to make accurate, efficient, repeatable material additions. However, each PAC algorithm deployment required some specialized knowledge and support that P&G engineers weren’t able to consistently provide across P&G’s global operations.

“We knew we had created a better mousetrap,” says Chappell, “but we were only able to support about 20% of the P&G deployment opportunities, so we begin seeking outside assistance. In 2001, we (P&G) licensed our PAC algorithm to Mettler Toledo, which has successfully commercialized its Q.impact material transfer controller. By using Mettler Toledo’s products and services, P&G engineers are now available to assist with additional PAC deployments.” (See “The Better Mousetrap Dilemma: Buy Versus Make” sidebar below.)

However, not all challenges associated with batching, dosing, and weighing can be solved with new hardware or software—or can they?

Dose of Regulations
Regulatory oversight is another batching, dosing, and weighing challenge that food, cosmetic, pharmaceutical and wine producers share. Whether that oversight comes from the U.S. Food and Drug Administration (FDA), the Alcohol and Tobacco Tax and Trade Bureau (TTB), or the rabbi, their goals are essentially the same—to ensure that established quality standards are maintained.

A statement in the FDA’s “Guide to Inspections of Dosage Form Drug Manufacturer’s” emphasizes the importance it places on weighing and dosing systems. It reads, “Critical manufacturing steps include the selection, weighing, measuring, and identifying of components and addition of components during processing. It includes the recording of deviations from the batch record, mixing time, and testing of in-process material, and the determination of actual yield and percent of theoretical yield. These manufacturing steps are documented when done, and not before or after the fact.”

Such emphasis illustrates why Wyeth materials manager Javier Suarez says, “We needed to become FDA-compliant to achieve our goal of becoming the worldwide supplier of Refacto. AspenTech’s weighing and dispensing software solution is a critical component for attaining this compliance, and we’re very pleased that our weighing and dispensing solution didn’t receive any observations from the FDA during the approval process.” Refacto is an intravenously administered product that helps correct deficiencies in the blood of people with hemophilia.

Now Add PAT
The stated goal of the FDA’s Process Analytical Technology (PAT) framework is to encourage regulated industries to design and develop processes that build quality into a product, rather than trying and testing it in after the fact. One of the more innovative technology investigations being advanced under the PAT framework is a collaboration between a global pharmaceutical manufacture, BOC Edwards Pharmaceutical Systems, and Bruker BioSpin to use time-domain nuclear magnetic resonance (TD-NMR) technology to provide online check-weighing.

“The FDA’s PAT initiative has highlighted that traditional sample checking, such as using precision scales, is no longer sufficient. This non-contact, check-weighing (NCCW) system represents a significant innovation and advance in check weighing,” says Paul Stewart, BOC’s technology director.
What makes BOC Edwards’s NCCW system so innovative is that it provides 100% in-line weight measurement at speeds up to 400 vials per minute, and it supports closing the loop to BOC’s filling equipment.

When we first began developing this article, we anticipated that user challenges would include measurement, such as load cells and tank gauging systems, and final control devices, such as analog verses on/off valves. We also thought there might be some industry-specific challenges identified. We were wrong on both counts. What we learned, and what you should keep in mind is, that when you’re facing batching, dosing, and weighing challenges, look beyond your own industry for solutions because it’s highly likely that the solution already exists somewhere.

The Better Mouse Trap Dilemma:
Buy Versus Make

DESPITE THE existence of many instrumentation and automation devices designed to perform very specific measurement or control functions, there continues to be integrators and engineers who argue that they can “build a better mouse trap.” The justifications are many, even though some may be suspect. Nevertheless, the biggest justification usually is verbalized as: “We bought this really great automation system, why don’t we use it?”

Certainly that argument has merit, and the tradeoffs of integrating a third party device as opposed to developing the equivalent functionality in the automaton systems software must be evaluated, but occasionally a device comes along that provides patented or proprietary functionality that’s impossible to replicate. One such device is Mettler Toledo’s Q.impact (Q.i) material transfer controller. What makes this particular device unique is its use of a patented predictive adaptive control (PAC) algorithm originally developed by Proctor & Gamble (P&G). The PAC algorithm accounts for such things as material-in-suspension, lags in input signal updates, and material kinetic forces to predict the precise moment the measured material addition will equal the target value.