by Chuck LaMacchia, The Progress Group, LLC
“Our competitor turns its inventory six times per year, but we’re only at four. We should be able to turn our inventory six times as well!” says the boss. “And get it done quickly!” From that, the inventory reduction crusade is set into motion. What’s the easiest way to lower inventory? Yep, slim down the stock on the medium and high movers. The inventory gets reduced, but expedites go up, and service goes down. You achieved six turns, but at what price?
Why does this happen? Because inventory reduction gets managed in a vacuum. Trying to control inventory independently of the variables that cause it is a no-win strategy. Inventory is a dependent variable based on the inputs of many factors including: demand and demand variability, supply lead time and lead time variability, supply chain design, manufacturing capabilities versus customer purchase characteristics, transportation modes, and desired service levels. In order to achieve sustainable inventory reduction while maintaining or improving customer service, the variables that drive inventory must be improved. Too often, inventory is adjusted to meet financial goals, without corresponding improvements in the variables that drive inventory levels.
Why is inventory the target? Because it shows up directly on monthly and quarterly financials. There’s no line item for supplier lead time, forecasting accuracy, or setup cost reductions. Inventory is usually a big number and in plain view to executive management and the shareholders. It is also expensive. Generally it costs 20% to 40% of the materials cost or COGS per year to store. Some of this cost is based on the value of the product (cost of money, taxes, insurance, scrap); the rest is based on storage (warehouse space, maintenance, utilities, equipment).
Here are 10 approaches to lowering your inventory. The key to sustainable reductions is to focus on the input variables. But remember, the overarching goal of the organization is to maximize long-term profits. Any attempt to reduce inventory should be in harmony with this goal.
Gather sales and inventory in dollars by item. Construct two Pareto charts. For the first chart, classify your items into A, B, C, and D (80%, 15%, 5%, 0%) based on sales. Then calculate your inventory for each group. Do your A items represent 50% of your inventory? If not, you may not have enough inventory for these items. A significant amount of inventory on low demand items may indicate problems with product run-outs, transitions, engineering change management, and managing obsolete inventory.
For the second chart, classify your items based on inventory. Then calculate the sales for each group. Again, do your A inventory items represent at least 50% of your sales? If not, inventory may be out of balance. These charts are an excellent way to begin looking at your inventory. After gathering this information, you have the makings of a supply chain data warehouse for further analysis.
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