10.5 Design for X (DFX)

Design for X or DFX is a structure of knowledge. It provides information about the methods to reach particular properties of technical systems collected and organized into suitable forms during the design stage. The contents of this information are essential and should be tailored according to the designer needs. Instead of modifying the production system according to the product, the product must be modified around the production system.

DFX is a value-added service in the manufacturing process. It is used to improve X, where X is the propagation of functions. A conventional design usually begins with a rough draft of components and assemblies. The rough drafts are then passed on to production and assembly engineers, who are responsible for the optimization of the products. Generally, the production and assembly problems are revealed at this stage and a request for modifying the design are put across.

It is important to identify the alteration in the early stages of the design. The later the change occurs, the more the increase in the costs. DFX is an important part as it helps in the selection of the idea about the product in the identify phase and in the assessment and management of the risk in the design phase. The revealing of the alterations in design in the early stages of development leads to cost savings, improves quality and reduces time to market.

DFX is a generic stage which is customized to develop more DFX tools quickly and continuously. The resulting DFX tools share a commonality and are easily executed and coordinated. This DFX process is, then, viewed from a wider perspective of Business Process Reengineering (BPR) to obtain a product which is produced minus any defects.

DFX helps to provide meaningful comparative data. It helps to quantify data in terms of cost, quality and regulatory conformity. DFX is a yardstick in terms of designs and at the same time it provides an indication of the possible advantages of one design to another.

Design for Production is the foremost tools of DFX. It refers to the processes which assess the performance of the production system. It answers questions such as “How much time it will take to complete the order?” or “How much stock is needed to keep the international supply chain running?” It is important to possess knowledge about the design of the product, the needs of production and the production system to answer these questions.

The DFX family is ever expanding and houses the family members listed below. The X in DFX can be substituted for different variables.

1. DFM-Design for Manufacturability/Manufacture/Manufacturing

This is a method of designing the parts of the product in a way that aids their manufacturing. DFM enhances manufacturability and provides manufacturing cost data for a product and its parts.

The importance of DFM was realized during World War II when the demand to build better weapons in the shortest possible turnaround time was high. Also, there was a shortage of resources. However, after the war, there was prosperity and a speedy industrial growth. The functions of design and manufacturing were carried out by isolated departments which resulted in an orderly development of products.

In the late 1950s and 1960s, organizations began to realize that the methodologies that were currently being used were not suitable for fulfilling the need of automatic and reprogrammable manufacturing. Gradually, organizations began to customize their designs and processes and started carrying out independent research for the same. The pressure from global competition and the desire to reduce lead time led to the rediscovery of DFM. The personnel from both the design and manufacturing departments were roped in to carry out the design projects. The manufacturing engineers took active part from the early stages and advised about the potential ways to improve manufacturability.

2. DFA-Design for Assembly

The need for DFA arose when the problem to increase the level of automated assembly highlighted deficiencies in current product design with respect to automation capability. Design for Assembly helps in the simplification of the form of the product, it decreases the components and thus decreases the total cost of components. The design should be easy to assemble. Therefore, it reduces both the assembly and production costs. Although, these days the X in DFX can be replaced by variables of cost, disassembly and recyclability, yet the variable of ease of assembly is constantly upgraded.

3. DFMA-Design for Manufacture and Assembly

DFMA is the combination of DFM and DFA. It helps in the optimization of relationships between design function, manufacturability and ease of assembly. This helps in cycle time reduction and reduction in the cost of production. DFMA demands consistent teamwork from all kinds of engineers, starting with the ideation of the product till the delivery of the product.

4. DFD-Design for Disassembly

This is a more recent method which helps in the easy disassembly of products and helps in quick and easy maintenance of products. This method is also helpful when a product or component needs to be recycled.

5. DFC-Design for Changeover

This method helps to give precise estimates of the changeover potential of the production machinery and the effect of the characteristics of the final design.

6. DFS-Design for Service

This is also known as the Design for Maintenance. It takes into account the way in which the subassemblies can be exchanged as quickly and easily as possible. The maintainability of a product depends on the chances of failure of a particular component or subassembly. This is accomplished by enhancing the ease of assembly and disassembly of these particular components. This also helps to justify the additional cost incurred to increase their capability.

7. DFT-Design for Testability

Design for Testability is a method that aids quick testability of subassemblies and the whole unit. This method also helps to determine how much the system is automated. This technology has grown tremendously and the systems are now using BIST to troubleshoot the problem by itself.

Other designs which are used are DFR—Design for Reliability, DFC—Design for Cost, DFQ—Design for Quality, DFD—Design for Diagnosis, DFI—Design for Inspection/Design for International and DFG—Design for Green.

Roles of DFX

1. Culture in an Organization

The execution of a DFX project requires an active interest from all the employees from all the departments. The departments would then report to the Board of Directors. An ideal DFX project requires a DFX champion who would report to the Board of Directors. This is important as having high expectations from the lower and the middle management (who is busy performing their routine tasks) is otherwise useless.

The champion’s work would be to pressurize the departments to allocate time and resources for the DFX project. The champion will have to be highly influential and should be able to convince the employees for their involvement. He should be able to disseminate knowledge about DFX, its goals and the benefits it would have for the organization. A DFX project requires assistance from all the departments. For big organizations, where DFX is already employed, the DFX engineers report directly to the respective functional managers like R and D, manufacturing or engineering managers.

2. Concurrent Engineering

Concurrent engineering means the synchronization in the development of the whole design, its parts, its tooling needs and its assembly process. The concurrent process helps save a lot of time and costs. Time and costs are saved due to the eradication of product respins. Respins refers to the reworking of a design. The reworking can be avoided due to the modifications and corrections in the design from the early stages of development. 

DFX is such a tool which involves people from diverse backgrounds who aid in the design process. These specialists from various fields possess knowledge of different components of the complete lifecycle of a product and give suggestions to the Design Engineers. The knowledge that the specialists share takes the form of strategies that the Design Engineers adhere to during the design process or the design review meetings with the field experts.

A product development team generally consists of concept design engineers, marketing executives, test engineers and customer engineers. DFX is a method which guarantees accurate information. When DFX is combined with concurrent engineering, it decreases respins and saves costs. They both are also useful in reducing the production and development cycle.

3. Strives for Continuous Improvement

DFX should serve as an ongoing tool. It should be merged with the other goals of the company like increasing customer satisfaction. DFX helps to reduce the product development time, quality and reliability of the product and also customer satisfaction. It also helps in the reduction of the cycle time which is a major indication of success.

Levels of DFX Analysis

There are three different levels of DFX analysis.

1. Following a general set of rules

The rules which are applied are not quantitative. Although the rules are either based on a formal employee’s experience or based on a formal checklist, it requires a human to interpret and apply them to each case. This is because each case is unique in its own way. While this is the case, it is also true that it is not feasible to start every design from scratch and some skill is required on the part of the designer to infer and use the rules appropriately.

2. Following a Quantitative Analysis

Every component of the design is assigned a numeric value depending on its productivity and this is referred to as Design Scorecard. The overall quality of the design is judged by adding up all the values. The numerical values that are obtained must be taken as a goal which needs to be minimized. The product is then redesigned based on this goal. However, even this level requires a thorough knowledge about the product and the process on the part of the designer.

3. Mechanizing the Complete Process

The mechanization of a process can be carried out using a computer. The quantitative analysis requires the knowledge of experts and they give valuable suggestions to make the design a success. If the analysis is carried out with the help of a computer, it would reduce the workload of a designer. He would then be able to concentrate more on the creative aspect. He can be more focused as his attention would not be diverted by memorizing the rules or checklists.

Advantages of DFX

The major chunk of the cost is dedicated to the design stage before the production of the product. However, the truth is that the majority of the cost is incurred when actual production begins and after the design is accepted. Therefore, it becomes important to consider the production and assembly problems at the product design stage to save costs and increase productivity.