Lean manufacturing is something nearly everyone in the industry talks about and strives to achieve. Lean manufacturing is a method of identifying and eliminating waste to improve the manufacturing process and give customers only what they are willing to pay for. Before we discuss ideas for reducing or eliminating waste, let's identify the types of waste.
The 8 types of waste within manufacturing spell out the word downtime:
Here are some real-world examples of how lean tools can be used to eliminate waste.
Reworking or scrapping defective products pulls resources away from their normal tasks, adds extra labor and material costs, creates potential delays, and could result in lost customers. Defective products can be the result of incorrect documentation, bad materials, unstable processes, lack of training, or other issues.
Shop floor example: During assembly, an incorrect part was installed, preventing the final assembly from functioning correctly. The defect was identified at final inspection and the line was stopped. Additional product was checked to determine the scope of the issue and to stop defective parts from shipping. Extra resources were needed to identify bad assemblies and make decisions about whether it made sense to rework or scrap the product. If items had already shipped, customers might need to be notified to verify or recall product. A lean tool to help reduce the chance of this happening is single piece flow of the product, also known as pull vs. push system. In addition, standardization, best practices, and Kanban could be used to decrease the potential of using the wrong part in the assembly process.
Office example: An invoice does not match what the customer received. Resources need to be allocated to investigate what went wrong and to determine if the customer has the right parts. The invoice and bill of lading need to be reviewed and compared. Lean tools to help here would be best practices, standardized work, and value-stream mapping (VSM).
A shop floor example is running more parts than the customer ordered. In addition to the material cost and wasted processing time, the company must decide if it makes sense to store and handle the extra parts in hopes the customer will purchase them later. Keep in mind that the customer could make a revision to their product, rendering the old parts useless. Should the company scrap the product, keep it in inventory, or sell it at a loss? Once again, resources will need to be assigned to deal with this, which adds cost and pulls resources from other work. A lean tool to help here is Takt time, manufacturing the product at the rate the customer is using it. In addition, VSM and single-minute exchange of dies (SMED) are great tools to prevent this from happening.
An example of overproduction in the office area is the scheduling area setting plans and quotas based on cycle times rather than actual customer needs. This causes operations to build product based on nonexistent demand, tying up resources, machines, and materials. A great lean tool here is Takt time, understanding the customer's actual demand, and then implementing a pull vs. push system and using VSM to streamline operations to meet the customer's Takt time.
You find this type of waste on the shop floor in a variety of ways, including when an employee or machine is idle, waiting for the downstream operation to provide product. This is often due to any combination of the following issues: push vs. pull manufacturing, cycle times not matched, WIP (work-in-progress), batch vs. single piece flow, not operating based on Takt time, and much more. Lean tools are VSM, work cell organization, line balancing, single piece flow, and pull vs. push manufacturing system.
An office example could be that purchasing is waiting for engineering to update materials, BOM, part masters, or others. This results in not being able to order the supplies needed and can cause shutdown or delays not only in manufacturing but also in inventory management and the supply chain. A great tool to eliminate this kind of waiting is to perform a VSM that focuses on the flow of information and value-added operations in the front office.
This type of waste is not like the other types that can be easily observed or measured. It relates to not utilizing talent and skill level, as well as not having a lean manufacturing and continuous improvement culture within the company. This waste is often generated by management or the company’s human resources staff.
Each person has unique skills and talents, which are sometimes more than what the assigned task or job requires. If you are not tapping into extra skills, you are not utilizing all the talents your employees could bring to the table.
To remove this waste from the office and shop floor, you need to embrace a company culture of employee empowerment, engagement, and continuous improvement. Establish an environment where every employee feels valued and responsible for helping the company become the best it can be. Training, solid understanding, commitment, and support from all levels of the organization to lean manufacturing are important to get everyone on board.
You also need to foster an environment where teamwork and the exchange of ideas are welcome. Employees should feel their input, thoughts, and comments are welcome, whether they relate to their workstation or to a different part of the company. To achieve this, give employees the tools they need, including lean, and allow them to communicate their ideas to leadership. This is not about employees complaining about everything—it is about bringing up an issue or concern and offering a possible solution. For this to work, true employee empowerment should be practiced. Only then will you be able to tap into all the talent within your company and remove waste to achieve value for your customers.
Transportation waste occurs every time an item is not where it should be and needs to be moved or transported. A shop floor example is having to move material from workstation to workstation. This results in non-value work, which the customer is not paying for. Causes for this can be poor shop floor layout, push vs. pull flow, batch sizes, multiple inventory locations, etc. Great tools to deal with this kind of waste are workplace and cell layout configuration tools like 5S, VSM, pull vs. push, and single piece flow.
An example for the office is when departments are not located where they need to be. If your engineering staff must travel miles to interact with manufacturing or sales or your schedulers or planners must walk to check on inventory or if a job has been started, you are wasting your resources. VSM should be used here to remove as much travel as possible to keep staff at their workstations. In addition, electronic communication and paperless systems like ERP, MES, and MRP can reduce the need for travel.
Maintaining too much inventory costs a company more due to needing to pay for processed material and labor, as well as inventory and material management, storage, and control.
A shop floor example is having more inventory stocked than you have orders, like having preassembled parts from a supplier in your on-site warehouse. Tools to manage and set appropriate inventory levels are Kanban systems, first-in, first-out (FIFO), just-in-time, ERP, MRP, and MES systems, as well as scheduling to demand and working with your suppliers to have them on the Takt time you are operating.
An example of an office area inventory waste would be ordering more supplies than manufacturing can process to meet customer Takt time. Kanban systems, VSM, FIFO, ERP, MRP, and MES systems are key tools to not overorder for manufacturing. As far as physical office waste, examples are ordering too many office supplies and batch processing of invoices, payroll, and other requests. For this kind of waste, Kanban, VSM, and FIFO are key lean tools.
This refers to any unnecessary movement or motion an employee must make to produce the product for the customer. A shop floor example would be an employee needs to walk to an area to retrieve tools or items so work can be performed. Tools to eliminate this kind of waste are 5S, VSM, and cell layout.
Office wasted motion examples are central filing, walking to copiers or fax machines, and needing to walk across the plant to interact, retrieve, or provide information. Tools to help here are plant and office layout, VSM, and work cell layout as well as 5S.
Excess processing is work that the customer has not requested and is not willing to pay for. This type of work can reduce your profits or make your operational costs higher than your competitors—you are doing work and not getting paid for it.
On the shop floor, this could be relying on quality control or inspection rather than improving processes to eliminate quality issues. For example, instead of improving a machine that is incapable of consistently meeting the tolerance need for a good product, the company chooses to inspect parts after they have been machined. The inspections are just a coverup of the machine’s inability. Poke-yoke, process improvement, and predictive maintenance are lean tools to reduce this kind of waste.
Some office examples would be entering the same data into multiple systems, making more copies than needed, generating reports that are not used, cumbersome processing, poor communication, human error, VSM, and poke-yoke (error proofing).