Standard Work Instructions (SWI) and Lean Manufacturing

Standard or standardised work instructions (SWI) are instructions designed to ensure the consistency, timing and repeatability of a process. They are kept at or near the operator's workstation, where the work happens. Standard work instructions are subject to lean manufacturing's approach of continuous improvement, also called Kaizen: document the best way currently known, follow it, and keep improving it. In short, update your standard work instructions regularly with better ways of doing things, and remove any waste that adds time or lowers the quality of your products.

What is lean manufacturing?

Lean manufacturing is a way of running production that focuses on removing waste – any activity that does not add value from the customer's point of view, such as waiting, unnecessary movement, overproduction, excess inventory and rework. It grew out of the Toyota Production System, developed in Japan in the decades after the Second World War. The term "lean" was coined by John Krafcik in 1988, and James Womack and Daniel Jones later summarised it in five principles: specify value, identify the value stream, make value flow, let the customer pull, and pursue perfection. Standard work is one of its foundations: you cannot improve a process reliably until everyone does it the same way.

Why standard work instructions matter

Without standard work instructions, operators have to rely on collective memory to perform tasks. That makes the process harder, because different people remember things differently. To be effective, standard work instructions need to be clear and understandable to both operators and managers. That is what "standardised" means: everyone can follow it.

With standard work instructions in place, you can expect improvements in four areas:

• The quality of the finished product
• The consistency of the finished product
• Throughput of the process
• Operator safety

Write standardised work instructions for lean manufacturing in 5 steps

Before writing, answer three questions: who performs the task? When do they perform it? And how do they perform it? The answers are the inputs for your standardised work instructions.

Then follow these five steps:

1. Observe the work

Start by observing the task you want to standardise. A simple process study sheet helps you take notes. When collecting details, record real times, stay focused, and don't guess what the workers are doing.

2. Understand the throughput of the process

Understand cycle times, inputs and outputs, and how many parts per period the process can deliver. Focus on takt time (available time divided by customer demand) and line balancing. Simple calculations are enough if you know the available time and the number of products required.

3. Define the task steps

Using a standard work chart, define the exact sequence of steps needed to perform the task. Add images, diagrams and tables to make it visual. Include the quality checks that show whether each step was done correctly.

4. Document the standard in-process inventory

Lean aims to keep it to a minimum. Define how much stock is needed at the start and end of the process, and how much work-in-progress may sit between the steps.

5. Create a standard work combination sheet

The standard work combination sheet (or combination table) brings the steps together for one operator. For each step it shows manual time, automatic machine time and walking time, plotted against the takt time. It shows at a glance whether the operator's work cycle fits within takt, where the operator waits for a machine, and where walking or waiting can be cut. It is a shop-floor tool, made by the people who study the process – not a project schedule.

SWI following the Kaizen approach need regular updates to keep quality and consistency high. Following these five steps leads to work that is done faster, problems that are solved sooner, less waste and lower costs.

Where REWO fits

REWO Guides hold the operator-facing side of standard work: visual step-by-step instructions with approval and version history, so each Kaizen improvement reaches the line as a new controlled version. See how REWO supports Lean and CI managers.

Read next: REWO for Lean and CI managers · How to reduce changeover times · Standard work instructions and SOPs