Design for manufacturability and comprehensive product development

Products have traditionally been designed in such a way that they could not be manufactured efficiently. Their designs have typically been released for production and were only manufacturable and managed to function when made in the shop where prototypes were modeled and assembled by highly skilled technicians. Effective product development must go beyond the traditional steps of acquiring and implementing design technologies as a solution. It should focus on administrative practices that consider the customer's needs, including these requirements in the design of the product, and ensuring that both the factory and its suppliers have the capacity to produce it effectively.

Products are initially conceptualized to provide a particular capacity and meet performance objectives and certain specifications. Given these specifications, a product can be designed in different ways. The designer's goal should be to optimize product design with her production system. A company's production system comprises its suppliers, material handling systems, manufacturing processes, workforce capabilities, and product distribution systems.

Generally, the designer works within the context of an existing production system that can only be minimally modified. However in some cases, production systems will be designed or redesigned in conjunction with product design. When design engineers and manufacturing engineers work together to design and streamline both the product and production support processes, this process is known as end-to-end production. The designer's design considerations for manufacturability, cost, reliability, and ease of maintenance represent the starting point for integrated product development.

The designer's primary goal is to design a product that works within the given economic and programming constraints. However, research shows that decisions made during the design period determine 70% of the cost of the product while decisions made during production only count for 20%. On the other hand, decisions made in the first 5% of product design can determine the vast majority of the product's cost, quality, and manufacturability characteristics. This indicates the great effect design for manufacturability (DFM) can have on a company's profitability and success.

However, the application of the DFM must consider the economic questions of design in general. You must balance the efforts and costs associated with design development and refinement with the cost and quality effect that can be achieved. In other words, the greater the effort to optimize the design of a product is justified with a higher value or with higher production volumes.

The effectiveness of the design is improved and its integration is facilitated when:

a.- Few active parts are used through the standardization, simplification and group technology of retrieval of information related to existing or preferred products and processes.

b.- Producibility is improved through the incorporation of DFM practices.

c.- Design alternatives are evaluated and design tools are used to develop a more mature and producible design before being released for production.

d.- The product and the process include a structure to balance the quality of the product with the design efforts and the robustness of the product.

The interest of design analysis is analysis of manufacturability. In the context of the global growth of competition, it is of crucial importance to optimize the launch time of manufactured products to the market. Timely analysis of manufacturability is an important tool to achieve this goal.

The manufacturability of a design is the probability that it can be produced according to an available set of machinery, tools and processes. The optimization of manufacturability considered up to this point does not include the generation of detailed process plans or cost estimation. In fact, it is a phase immediately prior to the planning process. This approach is a novel way to optimize the quality of the design before it is sent to the process planning system, avoiding the waste of resources involved in the planning of design processes that are not manufactured.

2. SIMPLIFICATION AND STANDARDIZATION

As a design is developed from the concept to a detailed level of the product, it is required to encompass physical and functional requirements that are defined according to how a part should accommodate and behave. Within the constraints of this approach, the designer must design or select a part for use. A designer may have several alternatives to design a part that meets the requirements of this approach.

While designing a custom part or selecting a new part may be the most optimal way to meet requirements from the designer's point of view, it may not be the best approach for the company. Product cost and quality can be negatively affected by the proliferation of specialty items that require specific manufacturing capabilities.

Minimizing the number of active parts through standardization not only simplifies product design but also results in lower operational efficiencies and inventories. A formal part standardization policy and an emphasis on the use of approved parts lists (APLs) for certain basic items.

Group Technology (GT) and Component Supplier Management (CSM) systems can facilitate standardization by retrieving similar parts to be considered for use within the foundations of a new design. Using a classification structure to store and retrieve design information, an engineer can avoid having to make redundant design steps, and the function of the design can evolve towards the use of standards. CSM systems maintain information about approved parties and their suppliers, thereby providing easy access and cross-referencing.

The engineer would determine the characteristics of the part needed for a product and identify similar parts that may be available and traceable. One of these parts may work the same way, or there may be some non-critical specification somewhere that can meet both needs. If the existing designs are not satisfactory, the design data can be used to facilitate the design of a new part, particularly with tools for Computer Aided Design. This approach can be extended to identify tooling and attachments that could be used, avoiding additional redesigns.

In addition to standardization, simplifying product design also offers significant opportunities to reduce costs and improve quality. Designers need to assess if there is an easier way to achieve the part function. Design for Manufacturing (DFM) tools and principles provide a structured approach to seeking simplified designs. Product complexity can be reduced through the use of modular building blocks for product assembly. By means of standard product modules, a wide variety of products can be assembled from a limited number of modules, consequently simplifying the design and manufacturing process.

By simplifying and standardizing designs, establishing design location mechanisms, and incorporating preferred manufacturing processes into the preferred parts list, design and production efficiencies are accentuated.

3. GUIDELINES IN PRODUCT DESIGN

General design guidelines have been established to achieve better quality, lower costs, improvements in automation and maintenance. As examples of these guidelines for Design for Manufacturability we have:

• Error-proof design of the assembly avoiding ambiguities in the process.

• Verification of the design of the product and its components to provide a natural or inspection test of the article.

• Avoid tight tolerances that go beyond the natural capabilities of the manufacturing process and design in the mid-range of parts tolerance.

• Design robustness in the product to compensate for the uncertainty in the manufacture of the product, its testing and its use.

• Design considering the orientation of the parts and their handling to minimize efforts that do not add value, to avoid ambiguity in the orientation and mixing of parts, thus facilitating automation.

• Design considering the ease of assembly through the use of simple movement patterns minimizing clamping steps.

• Use common parts and materials to facilitate design activities to minimize the amount of inventory in the system and to standardize handling and assembly operations.

• Design modular products to facilitate their assembly with the use of component blocks and subassemblies.

• Design considering the ease of servicing the product.

In addition to these guidelines, designers need to understand more about their companies' production systems, for example their capabilities and limitations. This in order to establish efficient and specific design rules that will promote the optimization of product design within the company's production system. For example, they need to understand the limitations of tolerances of certain manufacturing processes.

4. EVALUATION OF DESIGN ALTERNATIVES

With the traditional approach, the designer would develop an initial concept and translate it into a product design, making minor modifications as required to meet the specification. DFM requires the designer to begin the process by considering various design concept alternatives in the initial process. At this point, little has been invested in design alternatives, and much can be gained by focusing on a more effective design process. The only way to ensure that we are moving towards optimal design is to consider more than one design alternative. Using some of the previous design rules as a frame of reference, the designer creatively needs to develop design alternatives. Subsequently, the alternatives are evaluated within the objectives of the DFM.

In a typical Computer Aided Design (CAD) environment, design progress is made in the redesign analysis cycle. The analysis carried out in this cycle can be, for example, a functional analysis or a stress analysis. Although the ever-increasing power of computing available for design allows for more insight to be incorporated into the redesign cycle, it always remains designer-controlled. The computer performs complex design tests and provides the designer with high-level results. The designer uses these results and his experience to modify it before resubmitting it to the computer. A natural progression is to replace, where possible, human weakness in this cycle, weakness being understood as speed and availability,more than in terms of adaptability or design quality.

Design automation tools can assist in economic development of multiple design alternatives, as well as in their evaluation. These design tools include Computer Aided Design (CAD), Computer Aided Engineering (CAE), solid modeling, finite element analysis, group technology (GT), and Computer Aided Process Planning (CAPP). CAD / CAE tools help the designer to effectively pay for the development and analysis of design alternatives. CAD / CAE and expert systems can use manufacturing guidelines to develop producible designs. Solid modeling helps the designer visualize the parts,understand their relationships with other components such as their orientation and the separation distances between them during assembly and support the detection of errors and assembly difficulties. Finite element analysis and other design tools can be used to assess the ability of design to meet functional requirements, prior to manufacturing, as well as to assess the robustness of the product and its parts. Computer Aided Process Planning can be used during product development to help the designer evaluate the manufacturability of the design. Without CAPP tools, the level of manufacturing evaluation would not usually be performed until after the design was released for production. However,The use of these tools for design productivity should be managed as it can create a temptation for the designer to exercise too much creativity and lightly design a part instead of opting for the recommended standardization processes.

In addition to these productivity tools for design, there are others that help DFM analysis and suggest some complementary improvement opportunities. These are basically focused on analyzing the symmetry of the design, ease of handling of parts, supply and orientation and the total number of parts. They can also analyze assembly operations, design evaluation with respect to practices and tolerance requirements.

Once the designer has a basic understanding of DFM, they should also learn how to work more closely with manufacturing engineers and others who can provide feedback with some DFM suggestions for correcting certain problems. In summary, this design approach and support tools should help:

• Identify the design alternatives and their development with their respective economic considerations.

• Evaluate these alternatives with respect to the objectives of DFM

• Establish design standards based on DFM principles that can be quickly retrievable for new products

• Utilize design reviews that include manufacturing involvement in the design process to evolve producibility guidelines.

5. CONCLUSIONS

Design for Manufacturability and Comprehensive Product Development may require additional efforts in the early stages of the design process. However, the integration of the product and the design processes through business practices, administrative philosophies and technology tools will result in a more manufactured product that better meets customer needs, as well as a more seamless transition. fast and direct towards manufacturing and lower life cycle cost.

In an ever-increasing global competition, product design and customer service may be the fundamental way to distinguish a company's capabilities. Due to the current importance of product design, the concepts of Design for Manufacturability and Comprehensive Product Development will be critical to the success of companies. It will be the key to achieving and sustaining a competitive advantage through the development of high-quality, high-functionality, and highly-effective products in your manufacturing process through comprehensive product synergy and your design process.

Today the use of design support tools for manufacturability is not limited to large corporations or high-tech companies. The general use of computers allows these tools to be increasingly used in any design and production of any type of product and in any industry.

6. REFERENCES