What is a Water Spider in Lean Manufacturing?

Lean manufacturing aims to eliminate waste and increase efficiency in production processes. One key role that helps achieve these goals is the “water spider”. But what exactly does a water spider do?

An Overview of Lean Manufacturing

Lean manufacturing is a methodology that originated from the Toyota Production System in Japan The goal is to improve flow and reduce waste in order to maximize value for the customer

Some key principles of lean manufacturing include:

• Identifying and eliminating waste (muda)
• Improving flow by reducing work in process (WIP)
• Pull-based production based on customer demand
• Continuous improvement (kaizen)
• Visual management and transparency
• Standardized work and procedures

Implementing lean requires a cultural shift as well as practical changes on the shop floor It relies heavily on employee engagement and developing a workforce skilled in problem-solving

What is a Water Spider?

A water spider is a dedicated material handler in a lean production environment. The water spider is responsible for retrieving and delivering materials as needed to assembly stations.

Water spiders get their name from the whirligig beetles that can walk on water. On the production line, water spiders seem to swiftly “skate” from station to station, providing materials where they are needed.

Responsibilities of a Water Spider

The primary responsibilities of a water spider include:

• Monitoring inventory at assembly stations and replenishing as needed
• Retrieving materials from the warehouse or supermarket (storage area)
• Delivering parts, components, tools, and supplies to production workers
• Communicating with team members about material needs
• Escalating any material shortages or quality issues
• Maintaining the organization of the work area

The water spider has a dedicated material handling role, allowing production workers to focus on value-adding activities rather than material collection. This improves productivity and flow.

Benefits of Using Water Spiders

There are several benefits to using water spiders in lean manufacturing:

• Reduces waste – Workers don’t have to leave stations to get materials, reducing motion waste. Excess transportation and overproduction are also reduced.

• Improves flow – Consistent material replenishment means production isn’t delayed waiting for parts. Smoother flow through stations.

• Increases productivity – Production workers can dedicate their time to value-adding work rather than material handling.

• Enables pull system – Water spiders only deliver what is needed, when it is needed, based on demand. Enables just-in-time material delivery.

• Visual control – Water spiders can update kanban cards or signals for visual control of inventory and replenishment needs.

• Flexibility – Water spiders can fill gaps and pitch in where needed to balance workloads.

Implementing Water Spiders

Here are some tips for effectively implementing water spiders:

• Provide dedicated material handling training – Water spiders need knowledge of the material flow, inventory systems, replenishment procedures, and production processes.

• Setup visual signals – Kanban cards, two-bin systems, or colored lights/flags can help water spiders visually identify material needs.

• Determine spider routes – Plan the most efficient routes to maintain continuous flow. Routes should be standardized.

• Communicate material needs – Encourage workers to clearly communicate material needs with the water spider verbally or via signals.

• Level workloads – Balance the workload for water spiders across shifts. Monitor and adapt as needed.

• Update support tools – Use technology like tablets to provide water spiders real-time information to improve material flow.

Water Spider Process Example

Here is an example of how a water spider might operate on an assembly line:

1. The water spider periodically checks inventory levels at each assembly station using kanban cards. Yellow cards signal material is running low.

2. Jane at Station 1 flips her card to yellow for part A. This signals to the water spider she will soon need more.

3. When the water spider sees the yellow signal, he retrieves a standardized amount of part A from the supermarket.

4. The water spider delivers the new parts to Jane at Station 1 and exchanges the kanban card back to green.

5. This cycle repeats as the water spider continually loops to check signals and deliver materials as needed.

6. If there are no materials to deliver, the water spider may support production by assisting workers or performing 5S activities to improve organization.

Key Takeaways

The water spider is a dedicated material handler role designed to improve flow in lean manufacturing systems. By providing consistent material replenishment, they prevent delays and allow production workers to focus on value-added tasks.

Implementing water spiders requires training, standardized work, visual signals, balanced workloads, and integrating technology. When used properly, water spiders can significantly improve productivity, reduce waste, and enable just-in-time material delivery.