We are going to take a breather from blogging about Product Development Phases to write about Design For Manufacturability (DFM). DFM often comes up in our discussions regarding product design. Why should DFM be important to our customers? And, what are some ways that PADT Medical can help with DFM?
Start With the End in Mind
We understand that DFM is arguably the largest contributor to the total cost of your device or product. Perhaps most important to understand is the fact that changes which take place early on in the design process are relatively inexpensive. Once a product has been developed, it is very expensive to change the design to reduce manufacturing costs.
In fact, "cost reduction" initiatives often fail to pay for themselves. The following table (taken from "Design For Manufacturability", by Dr. David M. Anderson) emphasizes the effects of design changes on total development cost based on when the changes are incorporated:
Level of completion | Cost to find and repair defect |
The part by itself | X |
Subassembly | 10X |
Final assembly | 100X |
At the dealer/distributor | 1000X |
At the customer | 10,000X |
Stakeholders, Gather Around
Another way that PADT Medical reduces the likelihood of future design changes is to pull together a cross-functional team early in the product development. An ideal team could include personnel from a wide range of areas such as:
- Design engineers
- Manufacturing engineers
- Service reps
- Marketing managers
- Customers
- Finance reps
- Industrial/product designers
- Quality/testing personnel
- Purchasing reps
- Suppliers
- Regulation compliance experts
- Factory workers
We help our customers by assembling representatives from many of these functions. Our employees and expert network provide a diverse background that can be the source of cost saving input for the development process.
Follow Lessons Learned
We help our customers by applying design and manufacturing solutions that we and others have learned over the years. Here are a few rules of thumb that we keep in mind when designing medical devices for our customers:
- Design the most pivotal and challenging parts first
- Use the minimum number of fasteners and the same kinds of fasteners
- Fasteners may represent only about 5% of the products direct material cost, but all the associated labor costs can reach 75% of total assembly costs ("The Best Engineered Part is No Part at All," Business Week, May 8, 1989).
- Fasteners may represent only about 5% of the products direct material cost, but all the associated labor costs can reach 75% of total assembly costs ("The Best Engineered Part is No Part at All," Business Week, May 8, 1989).
- Order assembly so the most reliable parts go in first and the most likely to fail go in last. This is important for both factory assembly and field repair.
- Design parts to be symmetrical
- Design parts to be symmetrical from every possible view so that the part does not have to be specially oriented for assembly
- If symmetry cannot be achieved, make the parts very asymmetrical
- Design parts to be symmetrical from every possible view so that the part does not have to be specially oriented for assembly
- Keep tolerances as loose as possible
- A good rule of thumb is .002". When tolerances dip down below .002" price and time go up exponentially.
- A good rule of thumb is .002". When tolerances dip down below .002" price and time go up exponentially.
Bottom line: It Rarely Pays To Cut-Corners on DFM
