Design for assembly and Design for manufacturing are two different methodologies that are often considered as one, called DFMA. Design for Assembly is the optimization of the product and assembly process, while Design for Manufacturing focuses on the selection of materials and manufacturing processes.
Good assembly design is essential for manufacturability. The goal is to develop parts and products that can be assembled quickly and effortlessly. This blog post will give you a complete overview of assembly design. Keep reading.
What is Design for Assembly?
Design for Assembly, also known as DFA, is the process by which products and assemblies are designed so that they can be assembled easily and efficiently. The goal of DFA is to minimize the number of parts, the time required to assemble the product, and assembly costs.
DFA is an important tool for engineers in product development. Using DFA, engineers can optimize a product's design for assembly and ensure that the product can be assembled quickly, easily, and cost-effectively.
Typically, this happens at the beginning of the product development cycle, before prototypes are built. This allows engineers to make changes to the product design to facilitate assembly.
Importance of design for assembly
Helps reduce production time : DFA can help simplify the design process and reduce the need for multiple reviews and changes. This can reduce production times and speed up the creation of new products.
Helps reduce production costs : DFA can help you design better products at a lower cost by using fewer parts in your design.
Helps reduce material consumption and waste : DFA helps optimize production processes and reduce material waste by eliminating the need for repeated testing.
Helps increase product reliability : Through DFA, designers pursue product reliability by reducing the number of assembly parts, thereby reducing the probability of failure.
Facilitates product assembly and disassembly : Design for Assembly aims at modular design to facilitate product assembly. It also makes disassembly easier. This is essential for repair and maintenance of the product.
Helps to set up an automated assembly : With the help of DFA, the assembly steps are simplified and machines or robots can align the assembly parts, thus increasing the efficiency of production processes. This assembly automation means easier assembly and lower costs for the manufacturer.
Construction principles for assembly
Design for Assembly is a set of rules and guidelines to help you design your product to be easy to assemble. It's important to follow these assembly principles because they speed up the prototyping process, reduce assembly time and cost, and increase product quality and customer satisfaction. Below you will find some assembly principles.
Minimize the number of parts
One of the main objectives of DFA is to minimize the number of parts. The number of parts is an important indicator of the quality of a product's design. Good products generally have fewer parts, and these parts tend to be more durable and easier to manufacture, repair, and maintain. Additionally, it is also important to minimize the number of different types of parts and simplify the shape of each part.
Optimize operations and assembly processes
Try to reduce the number of assembly operations required to make product development processes faster, more manageable, more consistent and more productive. When designing a product for assembly, you must consider the type of assembly process that will be used across the product line. There are two main types of assembly processes: automated and manual. Automated assembly processes are generally faster and more efficient than manual ones, but they can be more expensive to set up and maintain. Manual assembly processes, on the other hand, are typically cheaper to set up and maintain, but can be slower and less efficient.
Consider modular designs
To achieve fast and efficient assembly, designers must consider modular designs and incorporate modular assemblies, which means using standardized components that are interchangeable in size and shape with other components.
Furthermore, the modular design offers many other advantages. One of the main benefits of modular design is that it makes the system more scalable. This means that a system can be easily expanded or changed as needed without having to completely redesign the entire system. Furthermore, modular design can make a system more flexible, allowing it to adapt to different environments or applications.
For example, a bicycle manufacturer might design a frame that is easily assembled with different types of forks, wheels, and components. This would allow the company to quickly produce different bike models without having to redesign the entire frame each time.
Integrated fasteners
The number of parts that need to be manufactured and assembled can be reduced by incorporating fasteners into the parts themselves. This eliminates additional screws, nuts or other components, speeding up the assembly process.
Another option is to design parts that can be assembled without fasteners such as screws or nails. Parts that fit together without fasteners are called mating parts. Snap-on parts are easier to assemble and disassemble and are less likely to come loose over time.
Create a symmetrical design
In product design and engineering, symmetry is often used to create a more aesthetically pleasing design or to make a design more functional. For example, many products are designed with symmetrical components so that they can be assembled easily and correctly.
When designing for assembly (DFA), engineers must consider the principles of symmetry to optimize the assembly process. There are two main types of symmetry considered in DFA: bilateral and rotational symmetry. Bilateral symmetry means that a product can be divided into two equal halves, with each half being a mirror image of the other. This is the most commonly used type of symmetry in product design.
Rotational symmetry means that a product can be rotated around a center and still look the same. This type of symmetry is often used in products that need to be assembled from multiple parts, allowing each part to be easily rotated into the correct position.
In general, products with more symmetrical designs are easier to assemble than those with less symmetry. By considering the principles of symmetry, engineers can design products that are easier and faster to assemble, resulting in lower production costs.
Use error prevention (or Poka Yoke)
Designers can also apply poka-yoke principles during the product development process. They can help prevent assembly issues by making it difficult to install parts incorrectly. Defect prevention consists of designing the product in such a way that it is impossible to assemble it incorrectly.
This can be done in a number of ways, such as: B. adding physical obstacles (e.g. a notch) to the part or using different color coding or shapes for different parts. By avoiding errors, assembly can become much easier and faster and the risk of errors can be reduced.
Use of available standard parts
Easy-to-assemble design uses standard, commercially available parts. This makes product assembly easier and more economical. It also makes it easier to replace parts if they break or wear out.
Using standardized parts during assembly offers many advantages. First, the total number of parts that need to be handled, sorted and assembled is reduced. This can result in a significant reduction in labor costs. Secondly, the required production resources and time required for assembly as well as the probability of errors can also be reduced. Finally, the quality of the final product can be improved because standardized parts are more likely to fit together correctly and function properly.
Keep Tolerances Realistic
If a part cannot be assembled within specified tolerances, the defect is likely in the design itself. In many cases, it is possible to redesign the part so that it can be assembled within the required tolerances. When evaluating whether the tolerance is realistic, it is important to consider all factors that affect the fitment, including:
- The size and shape of the part
- The type of assembly process (manual or automated)
- The qualification level of operators
- The type of equipment used
If the tolerance proves unrealistic, it should be adjusted. In some cases, the tolerance may be increased slightly to compensate for manufacturing variations. However, it is important to keep tolerances as tight as possible to ensure the quality of the final product.
Additional considerations
To design for assembly, engineers must first understand the assembly process. You need to know how the product will be assembled, what tools and equipment will be used and what the assembly sequence will be. With this information, they can design the parts and components so that they can be assembled easily and efficiently.
When designing your product, make sure the components are neither too small nor too large. Add features that make it easier to hold and move parts, align them, and insert them. Self-aligning and self-locating parts can significantly speed up assembly. Sometimes a small bevel or depression can make a big difference.
Be aware of certain types of elements (springs, cup-shaped objects, etc.) that can become tangled and stuck. If an assembly worker has to spend time untangling or separating bundled parts, it will be a waste of money and potential.
In short, designers should try to keep product design as simple as possible and avoid unnecessary features. This significantly reduces overall production and assembly costs.
6 tips for DFA to make a difference
Designing the assembly process is critical to translating customer requirements into a practical product design that can be manufactured. DFA allows us to visualize customer requirements and design a product that meets those requirements. However, DFA can be challenging, but there are some general tips that can make the process easier.
1. The type of product must be considered before production. This will help you understand assembly requirements and determine whether the product requires maintenance or repair.
2. When designing a product, it is important to anticipate potential problems during assembly or repair and develop solutions to correct these problems.
3. Test operations and assembly processes by producing prototypes to find and correct errors.
4. Use commercially available components (COTS parts) in your design. By minimizing the need for custom in-house machining and fabrication, the manufacturing department can focus on the unique or challenging aspects of your project. Using these parts reduces the time and effort required to produce your project.
5. Tolerances must be realistic or within reasonable limits. Extremely precise tolerances are unnecessary because they are time consuming and can lead to assembly problems and high manufacturing costs.
6. To improve the speed and accuracy of an assembly process, avoid small or large components and provide your parts with features that make them easier to hold, move, align and insert.
What is the difference between DFA and DFD?
There are some important differences between Design for Assembly (DFA) and Design for Disassembly (DFD). DFA focuses on simplifying the assembly process, while DFD emphasizes ease of disassembly. Additionally, DFA typically results in products with fewer parts and less complexity, while DFD often adds additional features to make disassembly easier.
DFA attempts to minimize the number of parts, assembly steps, and complexity of a product. The aim is to make the assembly process as efficient and hassle-free as possible. This often results in products that are simpler in design and easier to manufacture. DFA is typically applied early in the design process, before final specifications are determined.
DFD, on the other hand, focuses on making the disassembly process simple and efficient. The goal is to minimize the time and effort required to disassemble a product so it can be recycled or reused. DFD often adds additional functionality to a product, such as: For example, easy-to-remove fasteners for easier disassembly. DFD typically results in products with more parts and greater complexity. For this reason, DFD is often considered just an afterthought in the design process.
Injection molding design for assembly
Designing the assembly of injection molded components with other parts requires an understanding of different assembly methods and their impact on the overall design.
This section discusses the assembly of fasteners in injection molded parts and explains how they can be integrated into your design strategy.
During the design phase of plastic injection molded parts, designers try to reduce the number of parts used in their products. Reducing the number of parts can improve the efficiency and cost-effectiveness of a product. Designers should look for ways to incorporate fasteners to optimize assembly.
Mechanical fixation
Mechanical fasteners are the most common fasteners. This includes screws, nuts and bolts, rivets, bolts, brackets, and other metal fasteners used to join two or more objects together.
Select fasteners for your product, making sure the diameter of the screws is appropriate for the task, the head shape can be automated, and there are washers to prevent loose parts.
Another option is self-tapping screws, which save unnecessary assembly time.
Although the use of mechanical fasteners increases the manufacturing cost of the product, it also allows for easy repair or recycling at the end of its useful life if it is durable.
When designing with metal fasteners, consider material differences caused by environmental changes; Temperature and humidity can influence material properties.
Snap closures
Snap connections or snap fasteners, such as adhesive fasteners, are a type of built-in fastener.
They represent a very simple and inexpensive way to connect two elements. They are used when elements are too large or heavy for other types of fastening, such as screws or nails.
The pieces are joined together and a hook fits into a lower cut of an element, securing the pieces.
The hook and recess must be designed so that they can be removed again without damaging both components, otherwise a permanent connection will result.
Snap-on parts may incur higher molding costs due to the complicated cross-sections required, but assembly costs are relatively low.
3D printing project for assembly
Engineers are always looking for ways to improve their designs, making them faster, better, cheaper or lighter. This is where 3D printing comes in!
3D printing can make prototyping easier and more efficient. However, here are some DFA tips to keep in mind when designing your pieces:
1. Create the individual components that will form your assembly. Make sure the individual pieces fit together well and have no overlapping surfaces or curves.
2. When designing in 3D CAD, it is important to keep components separate. When two parts overlap, your 3D printer prints them together as if they were a single component. Ideally, moving assemblies with separate components would have no contact with each other, but this is not possible in real life. Therefore, it is important to ensure that there is negative space between all components of an assembly.
3. To create a 3D printed object with soluble support material, a printer must extrude the model material and the support material. If only model material is used, the model cannot be printed because the gaps created by air during the printing process cannot be filled.
4. To ensure that 3D printed assemblies run smoothly, reduce friction by printing components that must not be disassembled in one piece.
5. When designing a complex assembly for 3D printing, it is best to divide the components into individual parts that can be printed individually. For example, if you have an assembly with several parts made of different materials and colors – and your printer cannot print on different materials – you will need to print one part at a time and then assemble them.
Get started with DFA on WayKen
Overall, DFA is a powerful tool that can improve the efficiency of the manufacturing process and reduce the cost of producing a product. When used correctly, DFA can help improve the quality of the final product and reduce the time and effort required for assembly.
We also offer a variety of product design and manufacturing consulting services to help you prepare your parts for production, including DFM, parts inspection and more. Contact us today to find out more!
