In any setting, the manufacturing process is like a complex puzzle, and specifying the appropriate components and equipment provides the backbone for efficient, cost-effective operations. Manufacturing is indeed a precision game, where every machine, component and piece of equipment must work in unison. In the pharmaceutical and biopharmaceutical industries, it’s even more so; products directly impact the health and well-being of the population, making precision paramount throughout the manufacturing process. In this manifestly complex manufacturing ecosystem, everything from aspirin tablets to cough syrup are expected to deliver consistent dose, form, texture and taste, producing the same symptomatic relief and health benefits pill-for-pill, tablet-to-tablet, or dose-after-dose.
Scale equipment in the pharmaceutical manufacturing setting continues to play a critical and integral role in achieving quality and consistency objectives. To achieve such consistency and quality, the precise weight of each ingredient must be assured. For instance, bench scales and check-weighers can provide a high degree of accuracy in manual operations, while load cells and indicators with advanced integration capabilities can provide an automated weighing solution. System automation effectively decreases dependence on manual monitoring, manipulation and operation, minimizing human error. By applying advanced weighing technologies to complex pharmaceutical blending and batching applications, manufacturers can enhance quality control, improve inventory management, increase throughput and reduce labor and other production costs.
High-Accuracy Manual Weighing
Bench scales and checkweighers offer pharmaceutical manufacturers versatile weighing capabilities, delivering in-line weighing or package verification prior to distribution. Providing highly accurate, legal-for-trade weighments, bench scales allow manufacturers to mix precise ingredient amounts during processing and afterward employing checkweighers to confirm package quantity. Bench scales and checkweighers are designed to accommodate fast-paced automated processes, delivering instantaneous, exact readings in numeric or easy-to-interpret graphical formats.
Bench scales and checkweighers generally feature a simple interface to facilitate use, minimizing errors and increasing production throughput. By clearly displaying Over/Under/Correct, operators can identify at a glance if products meet process requirements for simplified monitoring. Also, to meet pharmaceutical hygiene standards, many bench scales and checkweighers are fabricated of stainless steel, designed to withstand washdown conditions. In pursuit of enterprise connectivity, these scales can also be set up to print results or communicate and store data via standard protocols, delivering to users, among other things, sophisticated product traceability.
Similar to baking, when manufacturing pharmaceutical products, such as vitamins and drugs in tablet form, operators must combine measured amounts of multiple ingredients. For instance, a company that manufactures supplements and vitamins must include the exact amount of each element each time the product is produced to retain its engineered and expected characteristics. By placing a bench scale at each station on the processing line, operators have the ability to precisely measure each component prior to adding it to the mixture. Common practice typically finds users placing batch ingredients directly onto the scale until the pre-determined amount is reached, ensuring batch recipes are followed accurately each time.
Once the dose forms are packaged, checkweighers ensure each container’s weight meets the designated amount listed on the package. Once the tolerances have been inputted into the scale, operators will be able to decipher immediately whether the product meets weight requirements. For example, if a given jug of powdered supplement is placed on the checkweigher, displaying Over/Under/Accept fan graphs allows operators to determine if its weight corresponds to what is listed on its label.
Scale Systems for Automated Pharmaceutical Processing
A weight sensor, or load cell, is a steel structure with strain gauges, or electronic sensors, positioned on the outside surfaces: two sensors on the top and two on the bottom. Unsupported on one end and fixed on the other, this structure acts as a cantilever. When a load is applied on the unsupported end, the sensors detect strain in the structure and provide an analog mV/V output. This output is interpreted by indicator electronics, and the weight indicator digitally displays the strain as the load’s weight.
For pharmaceutical batching and blending applications, electronic weight sensors can be affixed to bins, tanks or hoppers holding dry or pre-mixed ingredients, effectively transforming ingredient containers into highly accurate, in-line scale solutions. As materials are placed into a container, the electrical current running through each weight sensor changes, and this altered current is brought to and combined at a junction box. From here, the collected data is sent via interface cable to a scale indicator, which converts the current to a digital weight display.
In these operations, the accompanying indicator is a key component, because it can be programmed to control filling and batching applications through bin or hopper monitoring — observing each operation until its designated container meets a user-programmed set-point. Adding weight sensors to existing packaging and batching equipment is, in most cases, straightforward and unobtrusive, and not likely to disrupt operations if installed. Similarly, sensors equipped with stainless-steel housings withstand washdown in pharmaceutical and chemical applications.
Ingredients dispensed into the container cause the suspended end of the weight sensor to deflect slightly as it absorbs the force of the load. The force measurement is then translated as the ingredient’s weight. As subsequent ingredients are added, the weight sensor deflects an appreciable amount from its current position to represent the new ingredient’s weight. The suspended end of the load cell then returns to its initial position once the container is emptied. Adding to this design, some weight sensors have two pairs of electronic sensors located on the outside of the weight sensor structure, one pair on top and one on the bottom. This sensor arrangement helps ensure uniform compressive strain throughout the structure, which eliminates the effects of end loading, side loading and torsion effect.
Indicators are the heart of this weighing system, collecting and communicating data throughout the manufacturing enterprise for heightened process transparency and streamlined, cost-effective production. Indicators are also multitaskers, with some capable of simultaneously monitoring several independent scales, as well as directly controlling automated weight-based operations.
To facilitate at-a-glance decipherability, indicators can provide a combination of text and graphics that clearly convey process status and product weights. For instance, horizontal bar graphs can display over/under readings in checkweighing operations, vertical bar graphs display ingredient amounts, and pie graphs track rapid fill operations. This reduces read errors and allows operators to quickly take action if a process becomes obstructed or products do not meet weight regulations.
With fast-paced production speeds and minute margins for error, indicators with sophisticated data acquisition and management improve efficiency and throughput. For example, indicators can be programmed to automatically recall recipes, track product usage and update inventory records based on the amount of product used or remaining. Plus, indicators that interface with common industry-standard protocols enable the device to connect with diverse serial devices, including printers, bar code scanners, label printers and remote displays. This allows data to be stored and printed from the indicator, downloaded and reformatted by a host PC or accessed via an Intranet or Internet connection.
Automated Systems, Improved Production
Given that pharmaceutical end products must be pure and consistent, batching and blending applications must be verifiably exact to protect product integrity. In many plants, manufacturers store raw ingredients or pre-mixed formulas in tanks or hoppers to be dispersed during production. By integrating weight sensors and indicators with these containers, users can not only ensure accurate measurements and product consistency, but can also perform advanced data acquisition and inventory management procedures.
Coupling weight sensor technology with an indicator that stores recipe components ensures the exact amount of each ingredient is dispensed, without requiring operator intervention. The weight sensors are placed on each leg of the material container to capture readings, and an indicator with recipe-recall is integrated with plant devices and communicates with PLCs, PCs and other vital operating systems to provide an automated weighing solution. Once the measurement parameters have been entered into the indicator the automated weighing systems can be configured to recall recipes, routinely measuring according to the specified weight values or percentages.
As the pharmaceutical product moves through the production process, the indicator monitors the weight sensor to identify when the proper amount of product has been released. Once the product meets a configured dispensing station, the indicator sends a signal to begin dispersal of the first ingredient until the set point is reached. The indicator then uses its output to communicate this status to the filling equipment’s control system which, in turn, closes the product release valve on the first hopper and begins dispensing the second ingredient. The process continues until the batch is complete. Additionally, some indicators can store multiple recipes at once to ease product changeover.
Further, these automated scale systems can accommodate rapid product switchover, controlling multiple weighing requirements in a single application while delivering high-quality results. For additional automation, indicators can be configured to track product usage, keeping a running total for inventory purposes — maximizing process efficiency and reducing inaccuracies associated with operator error.
Benefits of Automated Production
Using a system that automatically tracks material disbursement and usage enables operators to increase inventory control, product quality and customer satisfaction, all while decreasing labor and production costs. Automated electronic scale systems offer unmatched reliability with minimal human error and costs.
Since customers depend on pharmaceutical products to improve or maintain their health, any minute inconsistency could have drastic consequences. Blending and batching applications hinge on a manufacturer’s ability to obtain accurate measurements. Therefore, utilizing an automated weighing system that makes operator monitoring obsolete, manufacturers can perform frequent quality checks, while eliminating the need for a separate checkweigher and manual supervision. By utilizing the indicator’s ability to communicate with and control plant devices, these applications will be completed the same way every time, which promotes product consistency.
Inventory management is directly correlated with a company’s pocketbook, as both shortages and waste result in significant lost revenue. For instance, when pharmaceutical plants experience shortages, this can lead to production halts, and extended downtime can be costly. Alternatively, given that some of the materials used to make these products have a window of viability, any excess, unusable materials must be thrown away, translating into lost profitability.
Automated scale equipment actively tracks and monitors product usage and remaining amounts, logging and communicating real-time product inventory updates. Plus, to ensure these records are constantly refreshed, the system relays this information to office computers, signaling when product inventory is low and reordering is necessary. For example, indicators can be programmed to measure the weight of a tank after each time the product is dispensed, repeatedly calculating the amount left. The indicator automatically totals product usage and eliminates risks of shortage and surplus concerns.
Today’s focus on efficiency and cost-effectiveness will continue to drive the way manufacturers piece together the components that make up their plant floors. Though the configuration may evolve, using equipment that promotes productivity and quality while simultaneously driving down costs will remain a constant. Implementing scale equipment integrated fully into production is a key element in streamlining pharmaceutical operations for enhanced profitability and customer satisfaction.
Published in the March 2013 issue of Pharmaceutical Manufacturing