DFM: Beginning With the End in Mind

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).
    
• 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
    
• 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.
    

Bottom line: It Rarely Pays To Cut-Corners on DFM

Phase 0: Concept Design - Set Your Trajectory

One of the ways we help our customers is by effectively performing the first and most important phase of the development process - the Concept Design.

In my last post, I described the importance of an established Product Development Process (PDP). The first phase in the process is the Concept Design Phase. The trajectory of the program is set in this phase and studies show that the outcome of the development project is significantly influenced by this initial trajectory.

At PADT Medical, we approach the Concept Design phase with a clear focus on achieving the following tasks:

· Research and define the users requirements
· Select a design concept with the best potential of meeting the requirements
· Identify the critical risks associated with the design and the program
· Establish the feasibility of overcoming those risks and launching the product

The successful execution of the Concept Design phase requires a constant focus on answering these questions in a cost effective and timely approach. Doing this requires the right combination of expertise and tools that enable a quick convergence on the right concept solution. The concept design phase should not conclude without a physical demonstration of the feasibility of the device. Significant value is added once a product concept is reduced to practice. It is very difficult to understand the risks in the development prior to building a medical device prototype.

At PADT Medical, we help our customers set the right trajectory by utilizing in-house expertise and tools to select the best concept options and evaluate them through functional testing. We do this by using a combination of an experienced development staff, advanced computer simulation, and rapid prototype testing. We work closely with our customers to quickly converge on design solutions that have the best chance of success in the market.

If you have questions regarding this topic or if you need help with converging on a concept design, don’t hesitate to contact PADT Medical. We can help Set the Right Trajectory for your medical device concept.