One Piece Flow Manufacturing

When you go to the car wash, you expect cars to be soaped, rinsed, and dried one at a time. But imagine the challenges if a batch of 20 cars all needed to be rinsed before the car wash could move onto drying them:  

• With that many cars to rinse, how long will you have to wait for yours to be ready? 
• If they rinsed your car earlier than others, will it start to dry with streaks? 
• With 20 cars ready at once, how difficult will it be to leave the car wash? 

With one car flowing through at a time, each car is ready sooner, without waiting for the batch to complete.  

This is the idea behind one piece flow manufacturing. Where batch manufacturing often creates bottlenecks, piles of unfinished work, and long lead times, one piece flow manufacturing takes a different approach: build one item at a time through a connected flow of processing steps.  

Let’s walk through what one piece flow manufacturing is, how it works, and how to put it into practice. 

What is one piece flow?

The one piece flow method, sometimes called “single-piece flow” or “continuous flow,” is a core principle of lean manufacturing. One piece flow means products move through the production line one at a time. Each unit is finished and handed off before the next begins. The focus is on smooth, continuous movement instead of letting work-in-progress inventory stack up. 

The opposite of this is batch production, which groups items together. For instance, 100 parts might get stamped before moving on for painting. With one piece flow, a part gets stamped, painted, and assembled without waiting for the rest. 

Here’s a quick side-by-side comparison of the two methods: 

Batch Production	One Piece Flow Production
Items move in large groups	Items move one by one
Long waiting times between steps	Quicker production times
Defects are harder to spot straight away and may affect an entire batch	Quality problems surface immediately
Builds inventory that takes up space and ties up cash	Lower inventory costs and need for storage space

The one piece flow method is used by Toyota Production System (TPS) for vehicles manufacturing, in electronics assembly (e.g. smartphones move one by one through soldering, testing, and assembly) and medical device manufacturing (precision tools benefit from unit-by-unit production, ensuring strict quality standards), to name a few examples. 

Advantages of one piece flow manufacturing

Companies that switch to one piece flow often see significant benefits. What really stands out is how a one piece flow strategy can be used to reduce the 3Ms (over exhaustion, inconsistency, waste) – key principles of lean manufacturing for eliminating inefficiencies and wasteful practices:  

1. Muri (over exhaustion of workers or equipment). Businesses have a higher likelihood of better engaging their teams when using a one piece flow method instead of batch production. One piece flow creates small, manageable workstations and tasks. This removes overburden on workers and machines. It’s also more motivating for operators to see results of their efforts immediately with one time flow.
2. Mura (inconsistency). A continuous approach focused on producing one item at a time makes it easier for frontline operators to achieve consistent and higher quality in the production process. Any mistakes show up right away for immediate correction with one piece flow. Defects don’t have the chance to spread across an entire batch. 
3. Muda (waste). By producing a single item at a time as it’s needed, businesses don’t have piles of extra inventory taking up floor space or workers waiting around for the next step in assembly. One piece flow also makes it easier to adjust production based on changing demand or a quality issue surfacing, without having to discard an entire unfinished batch of goods. Additionally, with goods moving through the whole production process faster, businesses benefit from delivering on shorter lead times and products reach the customer more quickly. 

Considerations before implementing one piece flow 

That said, one piece flow isn’t always the right fit. Some challenges include: 

• Setup Needs: Workstations need to be closely connected 
• Product Fit: Very large or highly custom products may not suit the method 
• Learning Curve: Teams need time and training to get used to the approach 

Even so, many manufacturers find the long-term gains outweigh the upfront effort of implementing the right setup and training for a one piece flow system. 

Before making the switch, ask: 

• Are the processes stable and predictable? 
• Can products be moved one at a time without major redesign? 
• Do we have leadership support and buy-in from the team? 
• Can we rearrange the layout to keep steps connected? 

A “yes” to these questions may signal a good fit. 

Implementing a one piece flow system

Switching from batch to one piece flow takes planning. Here are some key considerations for businesses implementing one piece flow: 

1. Map the Process: Track each step from start to finish and look for delays or extra handoffs. Make sure no single step slows the entire line 
2. Standardize Tasks: Clear, repeatable steps make it easier for operators to keep flow consistent 
3. Use Takt Time: Match the pace of production work to customer demand calculations exactly so you don’t over- or under-produce 
4. Design a Lean Layout: Arrange workstations close together such as in a U-shaped or cellular layout to reduce travel time and make communication easier. This helps make handoffs smooth as work pieces move from one operator to the next and allows teams to spot and solve problems quickly 
5. Encourage Improvement: Get input from operators on the production process and potential inefficiencies. They’re the closest to the process. And collect data to verify and optimize the production process. 

Why process is everything with one piece flow

Having stable processes that are executed on consistently is vital to the success of one piece flow. Frontline operators are the ones responsible for producing high-quality output one item at a time and not letting a unit progress through the production process if a quality issue arises. This makes training and process verification essential, ensuring standardization of steps and identification of process nonconformances that can impact downstream quality.  

On-the-job training tools can help operators get up to speed faster and provide contextual, just-in-time information on how to execute processes correctly. For instance, these tools can guide operators to fix a quality issue with standardized steps, such as walking them through how to recalibrate a machine. 

Digital audit and inspection software can also help surface problems faster and capture process failure data to identify inconsistencies in processes or training. For instance, if a process audit on one line reveals a nonconformance that may apply to other production lines, teams can immediately add a question to those audits as preventive action. 

One piece flow can be a big change for workers and the business. Monitoring production processes to check how efficiently and consistently the system supports continuous movement of single units through each step is critical to know how the change is paying off.  

Final thoughts

One piece flow manufacturing is a lean way to cut waste and improve flow by producing one item at a time. It reduces lead times, improves quality, and keeps production flexible. 

Making it work takes planning: mapping processes, balancing workloads, standardizing tasks, and verifying processes – including checking for takt time alignment, quality checks, and minimized inventory. The payoff is shorter cycles with less waste and better outcomes for both businesses and customers.