Industrial Process Optimization: Manufacturing Design

Manufacturing and processes

Which comes first: the product or the process? Naturally, the product takes precedence. It's essential to understand what you're making before determining how to make it. However, in practice, this sequence is rarely straightforward because companies don't start from scratch. Typically, existing process capabilities influence the design, and product designers are encouraged to stay within these established limits, avoiding designs that would require extensive new process development. In some industries, however, this conventional approach is reversed. For instance, in the semiconductor industry, process development often comes before product design. A test circuit is used as a technology platform to develop and validate the assembly process. Once this process is stable, product development begins, utilizing the refined process.

Industrial Process Optimization: Process Design

Process design is crucial in ensuring that production meets volume requirements. Whether the goal is to produce a single unit, one unit per day, or thousands of units daily, the manufacturing process is specifically designed to match these demands. This approach ensures that the process is efficient and adaptable to different production scales. The volume requirement is a significant consideration that directly influences the capacity that must be established, and this information is communicated early on to the engineering team responsible for designing the manufacturing processes.

Typically, the development team creates product prototypes in limited quantities, allowing process designers to observe and assess the product's characteristics directly. It is also beneficial when the product is produced with the active involvement of the developers and when process engineers participate in the product's development. This collaboration enhances the product's manufacturability and leads to improvements in the manufacturing design. The process design is refined through this integrated approach, resulting in a more efficient and effective production system.

Industrial Process Optimization: Seven-step approach to process design

Designing a manufacturing process is a complex task that requires a series of increasingly specific decisions, each leading to investments that will have long-lasting effects. The process typically begins with a focus on the final product and can be summarized with the following general approach:

1. Establish a Sequence of States for the Product: Begin by defining the various stages the product must pass through from start to finish within the manufacturing plant. Although working backwards from the end product may seem counterintuitive, this approach tends to be less prone to errors compared to starting from raw materials, especially when the final product is already defined. Key criteria for determining these stages include opportunities for (a) testing and partially validating parts and work-in-progress, and (b) outsourcing any upstream processes.
2. Identify Multiple Transition Methods Between States: Once the stages are set, explore various methods to achieve the transitions between these states. While the process suggested by product developers serves as a starting point, it is essential to consider alternative methods. These methods, known as unit processes, should be evaluated for their capability to deliver the desired product performance. Ideally, any capable unit process should yield the same quality in the final product. However, in practice, especially in high-tech industries, interactions between different unit processes can lead to a final product that doesn't function as intended, even when all individual characteristics are within tolerance limits.
3. Integrate Unit Processes into a Complete Manufacturing Process: The next step is to integrate the identified unit processes into a coherent, start-to-finish process that reliably produces functional units. The complexity of this integration varies by industry; in some cases, it might involve simply linking unit processes together, while in others, it may require reengineering the entire process through extensive failure analysis.
4. Determine Equipment Requirements: Identify the equipment necessary to carry out the process at the required production rate. This could involve selecting machines, though in some cases, it might be more important to choose the appropriate cutting tools and work-holding devices before selecting machinery. For example, in machining operations, the core of the process is often the control program, which may already exist from the product development phase unless the prototype was produced using additive manufacturing techniques.
5. Define Human Roles in the Process: Clearly outline the roles that people will play in the manufacturing process, which can range from performing tasks with hand tools to monitoring and responding to alarms in an automated system. This step also includes determining the number of operators required and their skill levels. As automation increases, operators' focus may shift from managing equipment to inspecting the product, such as using go/no-go gauges between automated operations. Moreover, automatic systems require programmers, and the nature of maintenance work evolves with higher levels of automation.
6. Acquire, Install, and Learn to Use Equipment: Once the equipment has been selected, the next step is to acquire and install it, while simultaneously learning how to operate it efficiently. This phase often involves making layout decisions within the plant. While some processes necessitate new machines, others may not. For instance, in assembly lines, the same conveyors and power tools might be used across multiple generations of products. However, in semiconductor wafer fabrication, new processes usually demand a new facility with stricter cleanliness standards, along with a new generation of machines and systems for handling larger silicon wafers.
7. Initiate and Scale Up Production: The final phase involves starting production and gradually ramping it up to the desired level. The transition from producing a single unit to making samples and eventually scaling up daily production typically reveals a range of technical, logistical, and managerial challenges that must be addressed swiftly.

Throughout this entire process, developers strive to work on multiple steps simultaneously, a method known as concurrent engineering. They fully recognize that not every development will be utilized, yet this parallel approach allows for greater flexibility and efficiency. Consequently, these steps do not follow a strict sequential order, where one must be completed before the next begins. Instead, they are often developed concurrently, with ongoing adjustments made as needed.

Industrial Process Optimization: The Hayes-Wheelwright product-process matrix

Robert H. Hayes and Steven C. Wheelwright introduced a manufacturing process classification system that distinguishes between process types and product types. The core idea behind the Hayes and Wheelwright matrix is that the chosen process must align with the product's characteristics. A significant point emphasized by this model is that efficiency can be enhanced by moving rightward and downward within the product-process matrix. However, this movement should not compromise effectiveness. The matrix also highlights that certain process designs naturally align with specific product characteristics, which is illustrated by the diagonal "line of natural fit." Moreover, it suggests that shifting processes towards the lower right can increase productivity.

Despite its utility, the Hayes-Wheelwright matrix has some notable limitations, some of which are discussed below:

1. Demand Variability: The matrix does not account for fluctuations in demand. For example, a low-volume, unique product might be well-suited for line production if the demand is stable and the equipment is appropriate. Such equipment might be older, slower, and less flexible, yet capable and sufficient in capacity. Many machine shops have such machinery, accumulated over decades, that can be revitalized with new jigs and fixtures, an overhaul of moving parts, and a control system retrofit, all at a fraction of the cost of acquiring new machines.
2. Line Concept Limitation: The matrix confines the line concept to assembly processes. However, not all line processes involve assembly. In machining, for instance, there are transfer lines and cells designed for one-piece flow through a sequence of steps, which the matrix does not fully consider.
3. Product Categories Exclusion: The matrix includes categories like "standardized products" and "commodity products" but omits configurable or customizable products. These products, which can range from computers to cars and airplanes, often represent some of the largest and most expensive manufactured items.
4. Project Process Misalignment: The matrix suggests that a project process is best suited for products produced only once or very few times. However, projects do not necessarily qualify as manufacturing, nor do they always take place in factories. Examples include the construction of oil platforms, cruise ships, and bridges, which are often managed as projects rather than traditional manufacturing processes.
5. Job-Shop Characteristics: The matrix distinguishes between job-shops and flow-shops, noting that job-shops lack fixed routes for workpieces. In a job-shop, machines are organized by type into "farms" (e.g., all lathes together, all milling machines together), and a workpiece may move through these farms in a unique sequence, processed on any available machine within each farm. The location of a workpiece in a job-shop does not indicate its position in the overall process, which is why a traveller document is attached. Traditional machine shops are often organized as job-shops, even in high-volume, low-mix, stable production environments like those found in the automotive and aerospace industries. The matrix's "white zone" for the job-shop concept extends to "High-Volume Standardized Products." See also: Leverage RFID for smarter asset tracking operations.
   
6. Emerging Technologies: The Hayes-Wheelwright matrix is also challenged by advancements such as additive manufacturing, particularly 3-D printing of plastic parts. Additive manufacturing holds the promise of enabling high-volume production of multiple products, all conducted most efficiently in a single operation. This development poses a significant challenge to the traditional views represented in the matrix.

In summary, while the Hayes and Wheelwright product-process matrix offers a valuable framework for understanding the relationship between manufacturing processes and product types, it also has limitations that must be considered, especially in light of new technologies and the evolving nature of manufacturing.

FAQ Industrial Process Optimization

What is the importance of aligning the manufacturing process with product characteristics?

Aligning the manufacturing process with product characteristics is crucial because it ensures that the production method is suitable for the specific requirements of the product. This alignment leads to greater efficiency, reduces the risk of errors, and optimizes resource usage. By selecting the right process for the product, manufacturers can achieve higher quality, reduce waste, and streamline operations, ultimately leading to better overall performance and profitability.

How can industrial process optimization enhance productivity without sacrificing effectiveness?

Industrial process optimization enhances productivity by refining processes to be more efficient, often by eliminating unnecessary steps, improving workflows, and integrating advanced technologies. However, it is essential to balance these improvements with the need to maintain or improve the effectiveness of the process. This means ensuring that quality standards are met and that the final product still meets all required specifications. The key is to optimize processes in a way that increases throughput and reduces costs while preserving or enhancing the effectiveness of the product.

What are the limitations of the Hayes-Wheelwright product-process matrix in modern manufacturing?

The Hayes-Wheelwright product-process matrix, while useful, has several limitations in modern manufacturing. It does not account for demand variability, which can make certain production methods less suitable if demand is unstable. The matrix also restricts the concept of line processes to assembly, overlooking other types of line processes like machining. Additionally, it does not consider configurable or customizable products, which are common in industries such as automotive and aerospace. Finally, the matrix is challenged by new technologies like additive manufacturing, which enable efficient production of high-volume, customizable products in ways that the traditional matrix does not adequately address.

Takeaway Industrial Process Optimization

The Hayes-Wheelwright model emphasizes the critical need to align manufacturing processes with the product's specific characteristics. This alignment is fundamental to optimizing production efficiency and maintaining high standards of quality. Manufacturers can reduce errors, streamline operations, and achieve cost-effective outcomes by carefully selecting processes that are well-suited to the product.

In the pursuit of optimization, it is essential to balance efficiency with effectiveness. While the Hayes-Wheelwright model suggests that moving toward more efficient processes can boost productivity, these improvements must not compromise the final product's quality or functionality. Effective optimization should enhance productivity while ensuring that the end product meets all necessary specifications and standards.

Semi-automation, supported by Automated Identification and Data Capturing (AIDC) technologies, offers a promising avenue for achieving this balance. AIDC can help bridge the gap between manual and fully automated processes by enabling real-time data collection and process monitoring. This integration allows manufacturers to maintain control over critical process variables, improve traceability, and make informed adjustments, leading to optimized production workflows that are both efficient and effective.

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Sources:

(1) Baudin M., Netland T. (2023): Introduction to Manufacturing. New York: Routledge