INVENTORY: Inventory has value on the balance sheet of a company, but it is not value. The customer will not pay you more for your product if you hold more inventory, and will also not pay you less if you manage to meet his delivery expectations with less inventory. While inventory will often be necessary (e.g. as buffer to compensate for variation in customer demand), it should always be considered to be waste and be minimised.
WAITING TIME: Waiting time is the unproductive time spent by employees waiting for something to happen. Often they will be waiting for another employee to complete his or her task or waiting for a machine to complete its cycle. While waiting, the worker is not adding value to the product and therefore waiting is waste.
MOTION: In many tasks, employees will spend a lot of their time walking. Walking from one part of a production line to another, walking back and forth to collect or deliver materials, or walking around their work cells. While walking, employees are not adding value to the customer, so motion is waste.
TRANSPORTATION: Closely related to motion is transportation time. This is the time spent moving materials and products around your plant or from location to location—a necessity if you have a large site or multi-site operation, but it does not add value to the product and is therefore categorized as waste.
DEFECTS: Ask most manufacturing people about waste and they will talk about scrap or defects. Making scrap and defects does not add value to customers’ products, and obviously should be considered waste.
OVER-PROCESSING: Production processes frequently incorporate processes that do not add value to the product and we should consider those processes wasteful and try to eliminate them altogether. Examples of this kind of waste include excessive inspection steps, packaging of work in progress or subassemblies that need to then be unpacked later in the process, and de-burring parts (when the drilling or cutting process that caused the burr can be redesigned to prevent the burr in the first place).
OVER-PRODUCTION: Over-production is the opposite of just in time. Over-production is producing more than is needed sooner than needed. Over-production usually manifests itself as work-in-progress inventory. Over-production is usually caused by big batches and unbalanced processes and is in some ways the worst form of waste as it is associated with increased inventory, more transportation of materials, and often with over-processing.