Concerned About Medical Device Manufacturing COGS? KMC Knows DFA

This is the third in our Reducing your COGS series detailing how KMC Systems reduces customer Cost of Goods Sold during the medical device manufacturing process through its Design-for-Manufacturability software. The DFMA® software is just one aspect of KMC's cost-saving Design for X (DFx) process.

In the previous post, we discussed the value of Design for Manufacturability in reducing the cost of manufactured medical device parts. In this post, we'll talk about how KMC reduces your medical device manufacturing Cost of Goods Sold by coupling the knowledge of our experienced engineers with our Design-for-Assembly software.

How DFA reduces your COGS

Design for Assembly (DFA) is a method used by design and manufacturing teams to transition a product design at minimum cost, focusing on number of parts, handling and ease of assembly.

KMC Systems Senior Principal Manufacturing Engineer and Manager of the Manufacturing Engineering Group, Dan Frisbie, explains the DFA principles for the optimization of the parts and system assembly.

The DFA principles include:

  • Design for the minimum number of parts: The fewer parts required in a device, the fewer parts there are to design or redesign, to fabricate, to inventory and to service. Part reduction also minimizes the number of storage systems, operators and assembly steps needed.
  • KMC Systems' off-the-shelf XYZ axis robot arm.
    This application of DFA implements KMC's scalable and flexible design for multifunctional parts that reduce COGS. Here, KMC's off-the-shelf XYZ axis robot arm moves pipettes (above) and trays (below). Only the end effector changes.
    KMC Systems' off-the-shelf XYZ axis robot arm lifts trays.
    Design multifunctional parts: Design flexible and scalable parts for use across multiple platforms for rapid product development. For example, "KMC’s Internal Research and Development (IR&D) has developed an XYZ axis robot arm," Frisbie said, "The design could be used in many different types of instruments with only minor customization. This would reduce overall design time and we wouldn’t have to purchase a robot from another company."
  • Use standard components and processes: The use of readily available components and proven processes shortens lead time and reduces cost.
  • Develop a modular design approach: Modular design is an important consideration for efficiency, testability and serviceability. The Systems-Level Modular Design Approach to Field Robotics MIT paper describes this approach perfectly. "Using pre-fabricated modules would greatly shorten development times. Also, substantial cost savings would be realized by using an inventory of reusable 'standard' modules that could be used for a number of applications. In theory, even a relatively small set of modules can be assembled into a very large number of robot configurations."
  • Minimize parts orientation and eliminate unmanageable parts: Eliminate ambiguity of part orientation through symmetry or exaggerated asymmetry, and avoid parts that tangle easily, such as springs and C-clips, for ease of assembly and to reduce assembly time. Poka-yoke through the use of smart part features addresses this concern by mistake-proofing your assembly process.
  • Minimize assembly directions: Eliminate the need for reorientation during assembly. In their book, Product Design for Assembly, DFA pioneers Geoffrey Boothroyd and Peter Dewhurst say, “Any required reorientation or manipulation of parts already assembled is an operation which adds no value to the assembly process. If possible, provide progressive assembly about one axis of reference. Exclusive use of vertical insertion is ideal. However, parts can be inserted sideways in manual assembly with high efficiency and the main requirement is to avoid the need for manipulating the assembly or previously assembled parts at any stage.” 
  • Eliminate adjustments: Former engineer Bob Evans, KMC Business Development and Marketing Manager, explains that "Designing parts for automatic alignment through guides, pins, direction of assembly features (ideally vertical), and using location features on or near datums eliminates tolerance stack-up, reducing the need for adjustment, which reduces assembly time."
  • Design for automation: Reduce labor costs by adding provisions for automated assembly methods for higher quantity throughput and process control.

Read on to learn how KMC's engineers implement these principles to design medical devices and instruments for assembly.

Use Design-for-Assembly knowledge and software to reduce manufacturing cost

The Boothroyd Dewhurst DFMA software package allows you to integrate the parts evaluated in the DFM tool with the assembly in the DFA tool to analyze the whole assembly process and related cost breakdown.

The DFA software provides a full library of parts-assembly processes and allows the designer to create custom processes. At each subassembly stage, the software displays all custom and off-the-shelf parts, as well as the assembly steps. Engineers can examine the material, cost, labor, time and difficulty of each subassembly in order to refine the overall assembly process.

The ability to upload photographs into the software for each subassembly stage facilitates cost-saving modifications because the engineer can visualize a part's size, function and design. 

COGS-savings requires supplier communication

The data provided by the DFA software facilitates collaboration and intelligent communication with medical device manufacturing suppliers.

"Having every detail in the fabrication of a product that your supplier is providing you allows you to discuss with your suppliers all costs associated with your product down to the nuts and bolts," KMC Systems Mechanical Engineer Will Brooks said. "The software also gives you an organized set of data that provides the ability to, step by step, look at the costs of the assembly process in a systematic, straightforward fashion."

Want to use DFA software? Just add experience

Successful implementation of the DFA software requires the knowledge of experienced engineers.

"The software allows you to account for the finest detail of an assembly, down to the time to untangle a spring, so the more experience you have in the production of your product, the more you are going to be able to account for every detail that is involved in building the product," Brooks explains.

You can examine everything about the assembly in the software, but it's up to engineers to recognize cost advantages. Recognizing that a PEM is designed too close to a bend can save more than $100 on assembly.

Key to cutting COGS? Part count reduction

Applying DFM and DFA principles to a slide holder assembly to reduce COGS
In this slide holder assembly example, metal rails can be replaced by ribs in an injection-molded part for part count reduction. Also, guides and automatic alignment eliminate adjustments, speeding assembly time.

If you only do one thing, minimize parts.

According to Assembly Magazine's Successful Design for Assembly article, parts tend to account for 72 percent of the total manufacturing cost. The article elaborates:

A simple goal goes a long way toward focusing a DFA project, and without a doubt, a part-count reduction goal is the best place to start, for two reasons. First, part-count reduction is the mechanism for eliminating labor content. There is no design tool that takes labor content out of a product. Instead, reduced labor content is the result of something-part-count reduction. DFA takes parts out of the product, and reduced labor content follows. 

The second reason for focusing on part-count reduction is that it is easy to measure and people can understand it. To start a successful DFA program, no other goals are required.

Skilled engineers know how to examine a part and its assembly process to reduce part count.

Replacing a screw with a snap reduces part count from 3 to 2, saving cost on labor and parts. Injection molding versus machining also reduces parts and reduces cost over time. Brooks gave the example of eliminating metal rails by designing ribs into an injection-molded part.

Control COGS

Engineers can use the DFMA software for all new product design projects, building DFM and DFA efficiencies into the design. This process can also be used in an ongoing sustaining-engineering role to reduce COGS for a product already being manufactured.

KMC is expert in the application of this tool and process in both applications.

The next post in our Reducing your COGS series will discuss KMC's overall DFx process for manufacturing your medical device.

Topics: KMC Systems, medical device design, medical device manufacturing, design for assembly, DFA, Reducing your COGS