High-Mix Low-Volume (HMLV)

What is High-Mix Low-Volume?

High-Mix Low-Volume (HMLV) manufacturing is a production method used to produce a wide variety of products within limited quantities. HMLV environments are typically characterized by high flexibility and agility.

• “High-mix” refers to the high number of product lines that are produced by one manufacturer.
• “Low-volume” refers to the low volume of finished products.

Sometimes referred to as MTO (make-to-order) manufacturing, High-Mix Low-Volume companies largely work on a contract-by-contract basis. The work and specifications are directly dictated by the customer, emphasizing the needs of the consumer as opposed to the needs of the product line or company.

How Do HMLV Operations Work?

High-Mix Low-Volume (HMLV) assembly operations produce a relatively small amount of product but have much more variation. HMLV manufacturers receive contracts and then augment their production environments to assemble the products according to their client's needs. These manufacturers will often be working on multiple contracts at the same time and shifting their production methods frequently.

Since HMLV operations are constantly changing, it is common for these manufacturers to assemble a wide variety of products in the same facility, including disparate products like medical devices, toys, electrical components, and more.

Due to the nature of contract work, workers may not see certain assembly processes for a few months at a time, making it difficult to remember the ins and out of each operation. For this reason, High-Mix Low-Volume manufacturers require intelligent tools to ensure effective assembly management within a high-mix environment.

Advantages and Disadvantages of High-Mix Low-Volume

High-Mix Low-Volume Advantages

• Flexible production: An HMLV production environment is ready to take on new projects and augment their production lines to meet their varying customers’ needs.
• Proactive improvement: Unlike low-mix high-volume methods, HMLV production environments are free to make small and continuous improvements that don’t require heavy investment, enabling these manufacturers to enact new improvements and innovations faster.
• Less inventory: Since most products are made-to-order (MTO), needed parts and materials are only bought for specific projects. At the same time, finished products move fast since the customer has formally ordered the exact amount that was produced.

High-Mix Low-Volume Disadvantages

• Low-yield manufacturing: Flexibility comes at a cost. Since the work is constantly changing, HMLV manufacturers never have time to fully optimize or automate the complete production lines.
• Complex operations management: With multiple production lines, HMLV manufacturing can get quite complex. Not to mention, production orders, workplace requirements, and machine usage can change from month to month and even week to week.
• Complex employee knowledge: With varying processes across multiple departments, workers can forget key processes as soon as they learn new ones. HMLV operations have to be careful to ensure their workers always know their tasks and responsibilities.

How to Optimize High-Mix Low-Volume Operations

HMLV productions are often quite complex and ever-changing, meaning the methods used to optimize high-volume environments are not always applicable. But with the emergence of Industry 4.0 and 5.0 technology, there are several methods and tools manufacturers can use to optimize their high-mix operations.

1. Standardize Your Methods

The first step to optimizing your HMLV production is to standardize your best practices, SOPs, and work instructions. Since operators will see a number of jobs from week to week, you can stabilize each process by standardizing the methods and tools that they use.

• Best practices: These are the best working standards that are dictated by a company's vision, ethics, and working standards involving quality, safety, and the workforce. Best practices can range from specific actions to broad methodologies.
• SOP (standard operating procedure): These are documents that explain the Who, What, and When of the best practices and frequently performed actions.
• Work Instructions: These are step-by-step instructions that guide employees through How your best practices are achieved.

2. Prioritize Flow

While there are many moving parts within an HMLV production, there are always opportunities to increase flow for the various elements within the product line.

• People: Your workers are the most mobile force within your operation. However, by cutting down their movements, companies can create a highly efficient operation. Ensure that the next three elements work together to prioritize the efficiency of the worker.
• Materials: Ensure that parts and materials are never too far from the workstations while also not overcrowding the operator.
• Machines: Create an optimized usage and maintenance schedule to ensure there is no unnecessary downtime when it comes to your machines.
• Products: Make sure that the product flows efficiently through the production line and quickly exits the production line when finished. A product buildup or bottleneck will hinder the whole production line’s ability to work effectively.

Effective HMLV productions will often move workstations, machines, and materials to optimize how people, materials, and products flow throughout the operation.

3. Improve Communication

The more complex the operation, the more important communication is. Within HMLV environments, it is imperative that companies enable workers and leaders to communicate effectively.

When jobs change and improve, workers need to know about these changes. Also, leaders need to have their ears on the ground and understand how the operation is running.

But how is this accomplished?

There are several lean methodologies and technologies that enable companies to maintain an environment that is open to suggestions and improvements.

• Regular meetings: To get everyone on the same page, hold frequent meetings to go through action goals, recent changes, and progress.
• Gemba walk: Go to the real place and observe the realities of the day-to-day operations. This will allow you to connect with workers and hear first-hand suggestions for improvements that can then be added to your work instructions, SOPs, and best practices later on.
• Andon procedures: Under Andon, workers are encouraged to illuminate problems on the production line as soon as they see an issue. Create Andon smart forms within your work instructions to quickly notify the right people when problems or opportunities occur.
• Digital employee feedback: When using VKS, workers can provide feedback and make notes directly within their work instructions while they are working. This practice enables workers to quickly provide feedback without sacrificing productivity on the shop floor.
• Digital alerts: Whenever there are new procedures added to a process, authors can program alerts to inform users of the change. As soon as users open the VKS guidebook, they need to confirm they have seen the changes before they can proceed, ensuring all communications are not overlooked.