Is your Design ready for Manufacturing?
Let me introduce in this article one of the most demanded topics when developing a product, Design for Manufacturing. This article will take you through the basics of this technique to ensure your product is ready for production.
What is Design For Manufacturing or DFM?
In this article I am going to elaborate on the topic of Design for Manufacturing (DFM) and how to apply it to your product invention.
A DFM is a series of technical guidelines and suggestions to design products that can be manufactured using standard production processes. These guidelines look closely into components costs as well as tooling and production costs.
It is often performed just before the production tooling for the product is fabricated and the start of mass production is imminent. However, it is a recommendable practice during the whole product development process to avoid late changes in the design.
Why is DFM important for your invention?
One of the most important aspects of a DFM is avoiding mistakes that could lead to quality and productivity issues during manufacturing. These quality issues in turn translate into production costs and, even worse, into customer complains and potential returns.
Apart from avoiding potential quality costs, one of the main goals of a DFM is to optimize the design of the product so it can be manufactured in the most cost effective way. Making some of these decisions early on can generate great savings in the final product and process.
Finally, DFM can help to estimate timings for your product manufacturing. Selecting the right production methods and supply chain can accelerate the time to production and avoid delays on critical components.
Which are the manufacturing constraints?
Design for Manufacturing, as the name suggests, consists in designing products that are ready to be manufactured with production processes available in the industry. In order to achieve that, there are some guidelines to be followed during the design of the products and components.
I am going to list some of the most common items to consider during the design phase that are mainly related to the production process constraints such as injection molding, casting or machining:
- Avoid or reduce undercuts and overhangs in parts design
- Add some draft angle in vertical surfaces of the parts
- Consider minimum radius in edges and internal corners
- Check the tolerances achievable by each production process and don’t use tight tolerances unless necessary
- Consider internal stresses and deformations during fabrication
- Think about any jigs and fixtures required during manufacturing
- Define surface finishes required such as texture, polish or painting
- Define any post processes required such as trimming, punching or printing
All of the above will play an important role in choosing the right process, equipment and manufacturer and it will also have impact on the cost of the part and tooling.
How can I optimize the assembly?
As with parts fabrication processes, discussed above there are certain guidelines to optimize the assembly of your final product. Pay attention to the following items:
- Use modular design whenever possible
- Simplify assembly of each component to the limit
- Minimize assembly directions
- Use of Poka-yoke features or only one possible way to assemble.
- Minimize use of fasteners, use snap fits instead
- Confirm your assembly tolerances by doing a tolerance stack
- Minimize handling of parts, specially small parts
- Minimize the use of flexible components
- Think about jig and fixtures to help in the assembly
The efforts and complexity of the final product assembly is usually underestimated, so following these guidelines will save you lots of troubles in the long run.
How can I save costs in my product?
Following the best practices for Design For Manufacturing, cost reductions is one of the biggest benefits of this technique. These are some guidelines to save costs on your product:
- Minimize the total number of parts used in your product
- Eliminate redundant parts in your design
- Reduce unnecessary packaging and product documentation such as user manuals
- Minimize product volume for logistics
- Use of standard parts and components whenever possible
- Eliminate mass in components which is one of the main drivers of cost
Applying some of these practices will save some costs in your final product which will translate in significant amount when volumes get bigger.
What is your quality and testing process?
Some usually overlooked aspects of manufacturing a product is the required quality inspections and testing that is performed on the product.
These activities require additional steps during the final assembly of the product and in most cases specific equipment and tools. All of this adds costs and time to the product manufacturing and should be considered or acknowledged during the design phase.
Some of these activities are:
- Components incoming inspection from suppliers.
- Final product quality inspection before and after the product is packed for shipment.
- Specific testing during manufacturing, such as power check or battery charging.
One common issue during manufacturing is the addition of too many inspection stages during development. This is normally due to design flaws that need to be gated during manufacturing. Solve potential issues by design so you don’t end up over-inspecting or having a high defect rate in your production.
Additionally, other aspects that are often overlooked during the product development are related to other areas of the product lifetime, such as logistics, maintenance service and returns. These aren’t part of the Design For Manufacturing practices but are being more and more relevant lately.
By thinking about the whole product lifecycle, you can avoid issues that could oftentimes be solved during the design stage and can have an impact on how the product will be used and received by the final user.
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