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What Is Manufacturing Inventory? Production Inventory Intro

Tuesday, October 13, 2020

British science fiction writer Arthur C. Clarke once said “any sufficiently advanced technology is indistinguishable from magic.”

Spend one minute in a modern manufacturing facility and you’ll see. Conveyor belts, cranes, mixers, extruders, blowers, heaters, storage tanks, lifts, shredders, compressors, robotic arms. Everything clicking and whirring together like clockwork.

In one end, a bunch of raw materials. Out the other, something whole and useful. And the process to get from one to the other is so complex that for the average person it’s almost inconceivable.

But there’s a method to it all. It’s called manufacturing inventory management, and it’s magical.

What Is Manufacturing Inventory?

Manufacturing inventory, or production inventory, is all of the supplies and materials on hand meant for the manufacturing of products. Retailers and wholesalers have inventories that include only items ready to sell, or merchandise inventory. But a manufacturing company’s inventory consists of goods in multiple stages of production. From raw materials on up to finished products ready to ship.

For that reason, a manufacturing company’s balance sheet has three categories for its inventory: raw materials, work-in-process, and finished goods inventory.

Raw Materials

Raw materials inventory is all the most basic materials needed in production inventory management. Things like produce, individual food ingredients, metal, plastic, stone, chemicals, and everything else that gets worked into finished goods. 

Take, for example, a company that produces jellies and jams. Some of the primary raw materials would be fruit and sugar (for the jam) and glass (for the jars). 


Work-In-Process inventory, or WIP inventory, is whatever inventory is past the raw material stage but not yet a finished product. Work has gone into developing the raw materials, but there’s still some boxes left to check before the product is ready for sale.

In our example, this could be an enormous vat of jam that’s still cooking, waiting to be finalized, put into jars, and sealed. It could also be sealed jars of jam that have yet to have labels affixed to them. Anything that’s past raw material but before finished goods is considered WIP inventory.

Finished Goods

Finished goods are the end of the line. They made it all the way through production and are ready to leave the nest. When a product is ready for sale and shipment, it’s a finished good.

Back to the example, this would be sealed and labeled jars of jam packaged for shipment.

These three types of inventory are the parts that make up the whole of manufacturing inventory. But there is another type of inventory not traditionally considered part of the big three of manufacturing inventory. That’s inventory packaging.

What Is Inventory Packaging?

Inventory packaging is the physical inventory used to package finished goods products in preparation for their journey up the supply chain. That may be the next manufacturer, a wholesaler, or a retailer.

Packaging inventory management and packaging control are important because inventory packaging cost can quickly spin out of control. Here’s how to get good at packaging control: Outsource your packaging inventory management.

Using a VMI (vendor managed inventory) agreement with your packaging supplier is ideal for most businesses. That’s because most businesses are experts at managing their manufacturing inventory, not packaging inventory. By outsourcing your packaging inventory management to a third party, you spend virtually zero time managing what you’re not intimately familiar with. Let someone else monitor, anticipate, and meet your fluctuating needs within agreed-upon levels.

Manufacturing Inventory Management Tips

Manufacturing inventory management is the process of overseeing and improving raw materials, WIP, and finished goods inventories. Just what does a company gain from improving their manufacturing inventory management? They:

  • Improve the accuracy of their manufacturing and fulfillment cycle
  • Keep their physical inventory and space organized, which optimizes cost per square foot
  • Save money by decreasing shipment and transport time and lowering the inventory carrying costs of in transit inventory
  • Save time streamlining production

Smart manufacturing inventory saves time and money. Here’s how to do it.

Choose the Right Manufacturing Inventory Process

Good manufacturing inventory management relies on a smooth manufacturing inventory process (that includes smart MRO inventory management). Here are a few different ways manufacturing companies deal with inventory management in production and operation management.

Perpetual Inventory In Production Management

Perpetual inventory is inventory that’s taken continually. Every time goods are sold or used, inventory is updated. If you’re thinking of manual inventory taking and trying to reconcile that with perpetual inventory, it’ll be tough. To manually maintain a perpetual inventory requires either a small inventory or an army of employees. 

Today, automated inventory software platforms do all the heavy lifting. Materials and parts moving around a warehouse can be tracked with barcodes or QR codes and accounted for with computers.

Manufacturing inventory management software tracks raw materials, work-in-process goods, and finished products. Once a system like this is in place, it largely runs on its own, and manufacturing inventory management becomes a matter of analysis.

Just-In-Time Inventory In Production Management

JIT inventory endeavors to manufacture precisely what’s needed to fill demand. Goods are created to-order. By manufacturing only what demand requires, production costs go down while production quality (typically) goes up.

Toyota famously uses JIT inventory to great effect. Their production system employs something called kanban cards. Every parts box used in Toyota’s manufacturing process has kanban cards attached to it. They list which parts in the box are used when and where. When a part is removed from a parts box, the kanban card is removed. The removed kanbans are periodically collected from assembly lines and sent along to parts factories. The parts factories then produce the necessary parts to replace what’s reflected in the kanban cards.

Supermarkets do a version of this, too. They only order to replenish what has been sold. They started doing that before Toyota, actually, and some people refer to Toyota’s kanban card approach as the supermarket method.

ABC Inventory In Production Management

ABC inventory is based around three inventory presumptions:

  1. That the majority of a manufacturer’s sales are a minority of their products. 75% of a company’s sales may be for only a dozen SKUs, for example. These are the “A” products.
  2. Conversely, that a majority of product types make up a minority of sales. 50% of your products account for 5–15% of your sales, for example. These are the “C” products.
  3. That the rest of your inventory falls in between A and B products. This is the inventory that doesn’t move as fast as A but doesn’t risk turning into worthless dead stock like C.


The implication is that different parts of your inventory have different inventory turnover rates. And that a manufacturing company can use those different turnover rates to make beneficial decisions about inventory management.

Are your slow-moving C products priced too high? Could you fulfill more A product orders if you minimized the resources used to create B and C products?

A classic example of this is identifying your C products and minimizing the production resources and storage space they take up so they can be used for A and B products. Well-done ABC manufacturing inventory unlocks a mountain of opportunity for the manufacturing operation willing to listen to it.

Consignment Inventory In Production Management

Consignment inventory is when a manufacturer gives finished goods to a supplier or retailer who then only pays for the product if it sells. It’s a useful lever for a manufacturer to pull if they’re unsure of the demand for their product. It’s also a good way to get products in front of the buying public with little risk for suppliers and retailers.

Focus on Production and Inventory Control

Inventory control is the part of inventory management that focuses on upholding and improving the operational standard.

Is your raw material being transported and processed in a timely manner? How long does it take to get from WIP inventory to a finished good?

These are the questions that manufacturing inventory control specialists address.

And successful manufacturing inventory management depends in large part on their answers.

Two crucial concepts that impact manufacturing and production inventory control are reorder points and safety stock.

Reorder Points

Reorder points are similar to par levels in the hospitality industry. These are the inventory levels you shouldn’t fall below. The right reorder points allow for time to get raw materials from their source and to work with those raw materials to get them to the next stage of the production cycle.

The thing about reorder points is that there are a lot of them. Every single raw material needs its own reorder point. And an inventory analyst who can set proper, informed reorder points is worth their weight in gold. It takes a lot of guesswork out of running a smooth manufacturing operation.

Safety Stock

Reorder points are set based on expected raw material supply and finished product demand. Safety stock, not so much. Safety stock is the amount of inventory kept on hand for unanticipated material shortages or demand spikes.

Manufacturer safety stock is larger than wholesaler or retailer safety stock because it covers both raw materials and finished products. Like reorder points, every product at every part of the production inventory management process should have enough safety stock to weather a storm.

Insulating your business from uncertainty is important, but it comes with a cost. Every square inch you use to store safety stock could be used to store your finished products with the highest turnover rate.

Manufacturing Inventory Software

Today, finding the right manufacturing inventory system is a matter of finding the right manufacturing inventory software.

Manufacturing inventory software streamlines the manufacturing process by monitoring inventory levels in real time. It allows for the management of inventory across multiple locations, and the creation of bills of materials, and manufacture and work orders.

The right manufacturing inventory software helps you do everything we described above. You’ll be able to avoid wasting resources on slow-moving products, know where to double-down to ignite your profits, and generally streamline operations.

Look for manufacturing inventory software that:

  • Allows you to add multiple production stages to a bill of materials, so you can be sure the right items are in the right place at the right time
  • Lets you house multiple work orders in a manufacture order, so you can add the right bill of materials or work orders to specific manufacture orders
  • Converts sales orders into manufacture orders so items that have yet to be manufactured can still be represented in an order
  • Creates purchase orders for out-of-stock raw materials (Hello, kanban cards!)
  • Creates work orders for disassembly, maintenance, and repair
  • Provides accurate estimates on a finished product’s final cost so you can roll out effective pricing strategies
  • Integrates with your accounting platform and generates invoices and packing slips

You’ll also want a manufacturing inventory software platform that generates an inventory and manufacturing report. For the uninitiated, here’s an inventory and manufacturing report definition:

An inventory and manufacturing report provides the values of sales and product inventory for manufacturers, along with indicators of economic growth or decline like sales ratios, how long existing inventories will last under current sales conditions, and rates of change.

You find manufacturing software inventory that does all that, you stare it straight in the eye, shake its hand, and introduce yourself. Because it’s the beginning of a beautiful friendship.