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Weighted-Bin Technology: Accurate Inventory Without the Heavy Lifting

08/01/19

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Thomas Toll, Senior Director, Supply Chain Operations

According to historians, evidence of scale use dates back about 4,500 years. The fulcrum scale, based on the ancient balance scale concept, is still used in advanced laboratory settings because of its simplicity and precision.

Of course, using a fulcrum scale to monitor supply use in a health care setting isn’t the most efficient tool since it doesn’t provide an accurate count for inventory. Instead, supply chain departments turn to common methods like manual inventory checklists, Kanban cards, and closed or open-shelf systems to track and replenish supply items. While all of these provide an acceptable way of securing the necessary information, they involve multiple steps and are subject to human error.

Experienced supply chain professionals have employed most, if not all, of these processes and are all too familiar with the hiccups that can result from human error. The inaccurate counts from traditional inventory methods waste time for supply chain leaders since the staffers cannot get a true and complete picture of their inventory.

So what can an organization do to avoid a never-ending guessing game of what’s exactly in their stock? A number of health care organizations are finding they’re able to get a more precise measure of their inventory by using weighted-bin technology. This type of inventory management system uses supply bins suspended from or sitting atop scales that are hard-wired into a system to record transactions based on changes in weight. Each time an item is removed from the bin, the scale shows the count for those items decreasing, indicating that inventory needs to be replenished.

Scaling benefits

Weighted bins can help supply chain departments with their inventory needs in more ways than one. The cost for using this more accurate scale can be 10 to 20 percent less than conventional, closed-cabinet systems. Those taking the greatest advantage of the technology are placing orders directly to suppliers who ship replenishment orders picked and containerized for individual locations. This is made simple through confidence in the accuracy of the orders being created.

I recently saw an example of how this system improved ordering efficiency at a small hospital. The facility, which had more than 4,600 separate stocked bins, started simply by recording the number of stock-outs (empty bins) each day. This allowed them to determine root cause and make corrections like changing PAR levels and lead times. They improved their percentage of stocked bins from 99.1 to 99.95 percent with 12 weeks of focused effort and learned to have great confidence in the accuracy of the weighted bins.

Use weight for correct count

In a hospital setting, a weighted-bin system is best used for items that require frequent restocking. These are found in high-volume clinical areas, such as emergency departments, critical care areas and general nursing floors, to name a few.

Of course, no system is perfect. Before deciding if a weighted bin system will be your go-to approach, here are some considerations to keep in mind:

  • Will the items being measured be charged to a patient or will they be non-chargeable items used routinely by hospital staff? Requiring staff to focus on chargeable supply allocation by patient can accelerate staff transaction process as well as increase accuracy and compliance in the patient charge process. Not requiring staff to allocate non-chargeable items to specific patients can save them time in the item retrieval process and improve compliance on correct accounting of the chargeable items.
  • Do you have adequate staff to monitor your inventory when it runs low? Typically one full-time employee is required per 50 stocking locations to monitor and update the system as needed. Stocking of substitute items and conversion to different items does require additional effort and resources as the weight of any different or new item must be assessed and entered into the system. Also, items of different weight cannot be stocked in a bin without affecting count accuracy so when transitioning from one product to another, stock must be replaced completely.
  • Are you prepared to engage stocking location leaders in pre-installation training and configuration of stocking location layout? A weighted bin system has significant differences from other automated supply dispensing systems and requires thorough training – especially for end users and affected supply chain personnel. Adequate time should be budgeted for this training.
  • When planning layout, be sure to allow adequate vertical space between rows of bins. You don’t want supplies in a lower bin pressing on the underside of the bin above, creating an erroneous quantity reading. A second layout consideration – which is most often learned the hard way – beware of putting bins with very lightweight items near HVAC supply ducts as the air pressure captured by the bin can falsely increase the registered on-hand quantity. Lastly, you will need to allow enough lateral space between bins, preferably ¼” as, over time, the suspended bins can move slightly to the left or right on the scale arm.  It’s important to keep bins from coming into contact with neighboring bins and creating reading errors.

Once you have assessed whether your supply chain department could benefit from this technology, you can move toward implementing the system by creating a reasonable timeframe for installation and committing to it. After the system is installed, it will be important to meet regularly with stocking location managers to review statistics like charge compliance and variances in non-chargeable expenses to ensure fluid operations.

The use of weighted-bin technology can eliminate a number of potential human errors. No longer does supply chain rely on the end user’s accurate recording of activities, pulling the correct card or pressing the right button. Instead, supply chain staff have a more accurate count on their inventory, knowing the exact amount of items in stock and the right time to replenish their supplies when needed.

While weighted-bin technology may not be the right approach for every environment, it’s certainly an alternative that deserves to be, well … weighed.

About the author. As senior director in supply chain operations for Vizient, Thomas Toll provides on-site supply chain leadership and mentoring to select Vizient members. A graduate of Indiana University’s Kelly School of Business and a veteran of the U.S. Navy., Toll’s health care career spans more than 46 years, with 40 years in health care supply chain management.

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