What are Mixed Model Value Streams?

Optimizing Mixed Model Value Streams: A Step-by-Step Guide

Given the manufacturing requirements of the 21 st century to maintain a balance between absolute versatility and efficiency, mixed model value streams are important. Mixed-model value streams are designed to orchestrate manufacturing in a way that enables production of several different products using the same production resource and getting the most from them for the greater good of higher productivity.

This blog will walk you through 10 key steps to implement and optimize mixed model value streams, based on Duggan’s model.

Step 1: Defining Product Families

The first step in implementing a mixed model value stream is to define product families. A product family consists of items that share common production steps or processes, which allows them to be grouped together for more efficient production.

There are two approaches to defining product families:

• The 80% Rule: Create groups where 80% of the process steps are common across all products within the family. This helps minimize unnecessary complexity and ensures that products in the same family can flow through the value stream with minimal disruption.
• The 30% Difference Rule: Create groups where the total workload required to produce two products varies by no more than 30%. This ensures that the products within a family don’t have widely varying production times, allowing for smoother flow and more efficient resource use.

By grouping products into families based on these guidelines, you ensure that your mixed model value stream can operate with both versatility and efficiency.

Step 2: Calculating Cycle Time

Once product families have been defined, the next step is to calculate the cycle time for each family. Cycle time refers to how frequently a product can be produced to meet customer demand and is a crucial metric for balancing the production schedule.

The formula for cycle time is:

Cycle Time = Total Production Time Available / Total Product Demand

By calculating the cycle time, you can ensure that production is aligned with customer demand and that your resources are being used efficiently.

Step 3: Machine Capability Analysis

The third step involves analyzing the capabilities of your machines to ensure they can meet the required cycle times. It’s important to assess whether the machines have the uptime and efficiency needed to produce the entire product family within the allotted cycle time.

To improve machine capability, you can use SMED (Single Minute Exchange of Die) techniques to minimize changeover times, ensuring that machines are utilized to their full potential. Reducing setup times between different products allows for smoother transitions and higher overall efficiency.

Step 4: Determining Production Interval

Next, you’ll need to determine the production interval for each product in the family. This interval represents how frequently each product will be manufactured. Shorter production intervals lead to more frequent production runs, allowing for reduced inventory and shorter lead times.

It’s important to ensure that your machines and production resources can handle these shorter intervals without becoming overwhelmed. By determining an optimal production interval, you can maintain a smooth production flow that meets demand without overproducing.

Step 5: Workforce Efficiency

In this step, evaluate the efficiency of your workforce in meeting the cycle time for each product family. One effective tool for this is the Yamazumi analysis, which visually represents the balance of tasks across workstations. The goal is to ensure that no worker is overburdened and that everyone is working within a 5% margin of the cycle time.

By optimizing your workforce’s capacity to handle varying production demands, you’ll ensure that your mixed model value stream operates smoothly and without delays.

Step 6: Balancing Production Mix

To maintain a balanced production mix, you can implement Heijunka, a technique used to level production and ensure that different products are produced in the right quantities. By balancing the mix of products with higher and lower workloads, you prevent bottlenecks and ensure a continuous flow of production.

Incorporating finished goods supermarkets or adjusting work hours are effective ways to handle fluctuations in demand. These approaches ensure that production is balanced and that resources are allocated in the most efficient way possible.

Step 7: Standard Work Development

Developing standardized work procedures is key to ensuring consistency in your mixed model value stream. This involves creating visual work instructions for employees that outline the steps needed for each task. To make these instructions clear and easy to follow, use photos, arrows, and minimal text to convey information quickly.

These standardized procedures help maintain efficiency, reduce errors, and ensure that production tasks are completed correctly, regardless of the product being made.

Step 8: Establishing the Pitch

A critical aspect of mixed model value streams is setting up a pitch system to monitor production intervals. The pitch represents a set time frame during which a certain amount of work should be completed. By monitoring this interval, you can ensure that production is on track.

For example, a pitch runner might check production every 15 minutes to ensure that products are being manufactured at the right pace. This allows for real-time feedback, enabling immediate corrections if any part of the process falls behind schedule.

Step 9: Production Schedule Control

Once the production schedule is established, a Heijunka box can be used to control and monitor the production flow. The Heijunka box helps you visualize how different products are being produced, ensuring that the right mix of products is maintained and that production is aligned with demand.

By keeping the production schedule under control, you can quickly identify any issues and make adjustments to ensure that the value stream remains efficient and productive.

Step 10: Adapting to Customer Demand

Finally, it’s important to build flexibility into your mixed model value stream to accommodate changes in customer demand. By using dynamic supermarkets to adjust inventory levels based on fluctuating demand, you can ensure that your production remains responsive to market changes.

This adaptability is key to maintaining an efficient mixed model value stream in a competitive manufacturing environment. By staying agile and responding quickly to changes in demand, you can reduce waste and maximize productivity.

Wrapping Up

Implementing and optimizing mixed model value streams allows manufacturers to produce a variety of products using the same resources while maintaining high levels of efficiency. By following these 10 steps, you can create a production system that is flexible, responsive to customer demand, and optimized for higher productivity.

Mixed model value streams are essential for businesses looking to compete in today’s fast-changing manufacturing landscape. By mastering this approach, you can ensure that your production resources are being used to their full potential, resulting in smoother workflows and increased output.

Now is the time to start incorporating mixed model value streams into your manufacturing processes and unlock the benefits of greater flexibility and efficiency!