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.

Who Needs A Product Development Process?

One of the ways we add value to our customers to help them understand the Product Development Process (PDP). Established medical device companies have proven PDP's that have been tested and refined through numerous product developments. Small and early stage medical device companies often enter into a development program without the benefit of an established process. This is where we can help. PADT Medical has an established and refined PDP that we utilize with companies that do not have one of their own.

A well defined PDP provides a high level road map that helps development teams understand how to navigate the medical device development process. Our PDP satisfies the FDA Design Control regulations while at the same time providing the efficiency and flexibility that meets the needs of companies developing innovative new medical devices. There are always surprises, detours, and hurdles in development. The PDP is the all important tool thats keep a program on track and the focus on the finish line.

When we meet with prospective clients, one of the first things we try to understand is where the medical device is on the product development roadmap. We have found that having a one-page overview that highlights the development phases, documentation, and procedures is an invaluable tool for communicating progress to-date and the work remaining.

Here is a link to PADT Medical's one-page PDP overview.

If you are developing a new medical device and you are unsure about the steps required to take your concept to market, feel free to contact PADT Medical. We can help you understand the process and provide tips on how to avoid some of the most common pitfalls encountered by device developers. In the coming blog posts, we will elaborate on various pieces of the PDP that we use at PADT Medical.

Two More Lessons On Requirements

On the path to helping our clients achieve success with their medical device developments, here are two more lessons we have learned about requirements.

Lesson 3: Focus on what-not-how

Perhaps the biggest potential mistake in the design process is to focus prematurely on the "how" characteristics in the requirements document. The attention early on should be on what the product does, achieves or could be. Don't focus on how it will achieve it. The requirements should focus on the what-not-how of the product.

One way to support success in this area is to make sure requirements and specifications are "independent" measures and not dependent measures. For example, in a potential medical device, actuation rate would be an independent variable that would depend on the design of the mechanism and power source that powers the actuation. These how's should not control what your medical device could achieve.

Lesson 4: Release and track changes

Requirements change. The goal is to make sure that changes are clearly communicated to the design team in order to facilitate success. We quickly complete a requirements document and release it. Any changes that occur go through an approval process, and the act of changing and disseminating the revised requirements document is an effective communication tool. We make it easy for clients to design, communicate and reach their ultimate goals.

At PADT Medical we work closely with clients to help in every aspect of getting their idea to market, including developing medical device requirements that enable success.

Two Lessons Learned on Requirements

On the path to helping our clients achieve success with their medical device developments, here are two lessons we have learned about requirements.

Lesson 1: Capture them

From the moment you begin discussing the details of a new product, begin describing its requirements and specifications. There are many creative ways to gather these. The key is to "set the trap" and start recording. This is a mindset and reaction. When you hear of a requirement, capture it by recording it on the fly into a document. We'll get this information into the Product Requirements Document. Over time you will have an impressive list of requirements that you can review to create clarity on the goals.

Lesson 2: Don't get distracted

It's easy to get distracted by focusing on the organization of the requirement document, the wording of requirements or going out of scope and focusing too early on the specifications. We help our clients avoid this. The goal should be to capture the requirements and refine them later. One thing to keep in mind is that there is no ideal organizational method, so don't get hung up on that. Also, specifications can remain unclear until significant development testing is conducted. Don't get too excited about defining detailed specifications before their time.

The requirements process can seem onerous, and so at PADT Medical we work closely with clients to help in every aspect of getting their idea to market, including developing requirements that enable success.

Medical Device Requirements vs. Specification

There is occasional confusion when discussing what it means to establish "requirements" for a medical device project. The word is so generic that few people agree to its meaning. One thing we have found to be helpful is to define the difference between a requirement and a specification.

We define a requirement as a medical device characteristic that would be described by the end-user or customer. It is typically a general statement of "want" about the product. We define a specification as a "metric" that measures how well that requirement is satisfied.

In an ideal world, each customer requirement would have a single measurable specification. For example, the customer might state that the medical device must be lightweight. The obvious specification (or metric) would be product weight. This is something that we can measure in the lab, compare to a competitive product and track over the course of development.

So a requirement uses customer language and a specification uses engineering language. We'll be discussing four lessons we have learned about requirements in our next posting.

Making it Easier: Requirements

Our process makes it easier for innovators to take their concepts to market. One factor is how we work with clients to develop clear "requirements" in the beginning of every project. It's one of the keys to our clients' success.

In our experience, unclear design requirements are the most frequent source of misdirection in a project. When time-to-market is critical, a detour in the project development path can significantly threaten the life of a product.

This is why at PADT Medical we make requirements a requirement. No joke! The good news for our clients is that we guide them through it, so rather than an onerous process, it's one they recognize as value-adding and on the path to success.

There is a reason why ISO, MIL Specs, textbooks, and other professional publications insist on starting with defining and documenting design requirements. When this "best practice" is skipped the cost to the program is realized in the end.

There are numerous books and sources available to describe the process of collecting customer requirements. A book we refer to is "Product Design & Development" by Ulrich and Eppinger. The FDA Quality System Manual also offers some good insights into some of the questions that should be asked when collecting requirements. We highly recommend becoming familiar with the Requirement Engineering in order to successfully develop new products.

Don't worry: we'll take you through the requirements process and whatever it takes to succeed!