Design For Manufacturability

Business Metrics Series

Design for Manufacturability (DFM) has its roots in a concept that may go back to the time of Leonardo DaVinci in the 15th Century. DaVinci's folio 8 of the Codice Atlantica used exploded views and detailed descriptions to explain to the craftsmen how to manufacture the design. This was a mechanism to convert reciprocal motion to rotary motion. The concept of clear communication of instructions was utilized to insure that the device was properly built. DaVinci understood the limitations of precision available to the craftsmen. He also allowed for language problems by creating detailed assembly drawings showing exactly how the device was to be put together.

Do the terms Simultaneous Engineering, Concurrent Engineering, or DFM have any relationship to DaVinci? Absolutely! Depending on the industry you're in or the professional society you belong to, you may be familiar with only one of these terms. What do they have in common? They are our modern terms for methods that re­discovered DaVinci's technique. Design the product with a complete understanding of the capabilities of the people who will build it.

What has happened? How did we lose this process view? Specialization! Since the beginning of this century, specialization has created barriers between the different functional areas. Everyone has become a specialist. This is due to the incredible amount of knowledge an individual must utilize in their function. What have we lost because of this specialization? We have lost the ability to look at a problem from a broader perspective. This myopia, this single minded purpose, created the wall between Design Engi­neering and Manufacturing.

What have we re-discovered? Multi-functional teams can create a better product in less time and lower total cost than each of the individual groups working independ­ently.

There are several properties the World Class Manufacturer utilizes in the DFM process. One of these properties is that of trust. Trust between departments. Trust to allow the goals of the business to transcend the goals of each individual group. The practice of Design Engineering creating a masterpiece of technical excellence and throw­ing it over the "wall" to manufacturing to produce is no longer economical. Manufacturing may spend as much time and effort to create a product that can be made. This "wall" must be torn down to allow improved trust between the groups, just like the Berlin Wall.

By creating a team that includes Marketing, Design Engineering, Accounting, Manufacturing Engineering, Purchasing, Materials, Industrial Engineering and Produc­tion, a synergy is created. Synergy is an energy for creativ­ity and efficiency that is larger than the sum of its parts. In this process all the specialists work together from the beginning to bring a unique, quality product from concept to market in less time and at a competitive cost.

An example is the automotive industry which brings product, process, and production people together at the beginning of the design phase. Equipment and part suppliers, marketing, sales and distribution are also included on the team. They collaborate on each phase of the design process. A sample result: GM Canada produced a new sports car engine in 4 years rather than the usual 7 years. An example from a Hewlett-Packard team effort created a new printer, conceived and brought to a high volume market in under a year from the traditional 3 year development cycle time.

"... the single most important reason for delays in develop­ment activities is the absence of multi-functional (and outsider) representation on development projects from the start", Quote from Tom Peters book Thriving on Chaos ­Handbook for a Management Revolution .

"True" cost to manufacture

We have discussed the history of DFM, "over the wall" concepts, and the need for multi-functional teams. In this section we cover a performance metric of DFM and getting the design team "true" cost to manufacture data. It is said that 80% of the Life Cycle Cost (the cost of the product that spans from design to post warranty) of a Product is determined by the 20% invested in the design of the product. Most design cost-tradeoff decisions are based on estimates of components at the end of the design cycle. At this stage it is too expensive to alter the design radically for manufacturability and reduced Life Cycle Cost.

"Experts estimate that a similar percentage of a product's quality is also determined early in its design. Because excellent production cannot usually compensate for poor design, a company must have well-designed products before it can attain competitive manufacturing costs, quality and market responsiveness". Journal of Business Strategy July/August 1989

Another study estimated that if a change in design prior to manufacturing release cost $1, a change after Manufactur­ing release cost $10 and a change after the product was in use by the customer would cost $100! You can clearly draw the conclusion that it is less expensive to make it right the first time. To that end, Hewlett-Packard has developed the Break-Even-Time (BET) metric.

The BET Metric is used for all product design efforts to trade-off development costs against the time it will take to recover these costs.

The BET methodology requires the participation of R&D, Marketing, and Manufacturing early on in a project. The team works together from the time the product leaves the investigation stage until sometime after it is released to the marketplace. Estimates of investment, sales volume and manufacturing costs are used to generate a target for the product's profitability and when this will be achieved.

BET is composed of two sections: Time To Market (TTM) and Break-Even After Release (BEAR).

Simply stated: BET= Cumulative Net Investment/Cumula­tive Net Profit; the lower the BET the better the perform­ance.

Manufacturing costs are determined utilizing Activity Based Costing (ABC) techniques. This means that a design that uses fewer parts and standard components will have a lower cost estimate. The design team also has available a list of manufacturing processes and their associated costs. For example: a printed circuit board with a few Surface Mount Technology (SMT) components that are inserted by robots is significantly less costly to produce than back loaded parts. Back loaded parts are those parts that must be manually attached to the PC Board.

Leverage (re-use) of existing designs is also a significant factor in reducing costs.

"Companies are finding that being first to market with a product or service generally ensures a 50% market share". Management Today November 1989

Using the BET metric you can reduce the time lag between product development, marketing, and sales. In addition you can effectively evaluate the tradeoffs between product development costs and market intro­duction loss of share caused by a delay.

Use of DFM best practices can increase product quality, lower total Life Cycle Cost and increase market share all at the same time!

Tools to aid the team in consistent DFM practices.

So far we have covered DFM history, true cost of manufacturing, and the necessity for speed in development. The section of the article covers computerized aids to process planning and the integration of the design and manufacturing capabilities.

Concurrent Engineering is composed of several physical elements. One is Computer Aided Design the other Computer Aided Manufacturing also known together as CAD/CAM. Another way to achieve concurrent engineering is by putting the whole multi-functional team in the same location, as Chrysler did below.

"According to Sandy Emerling ..., the team concept used in the Viper program has streamlined the development process.

We've never done anything like this before. Everybody on the project works in one large room, from the designers to the engineers to the accountants and the production supply people.

When there's a question, it gets answered in a few minutes, face to face so there are no misunderstandings. We are trying to get from concept to market in three years, and it looks like we're going to make it." Quote from Popular Science Sept. '91 Article on the Chrysler Viper Project.

"The benefits of Concurrent Engineering:

* Development time 30-70% less

* Engineering changes 65-90% fewer

* Time to Market 20-90% less

* Overall Quality 200-600% higher"

Business Week April '90 National Institute of Standards and Technology

One objective of DFM is improved communication, either through electronic means or face-to-face. An advantage of the flow of information from a CAD system is that the geome­try is passed directly to a post processor that creates the program for a numerical control (NC) machine and the tooling used to verify the part is made correctly. Alternatively, the information can be passed to a rapid prototyping machine (aka 3D Fax machine) or a simulation program to verify component design. This electronic commu­nication can take place side by side or around the world. It helps improve the communication between the designer, the manufacturing engineer and the machine operator. This information can also be passed to a Coordinate Measure­ment machine (CMM). This verifies that the NC machine produced part is to the CAD specification. The introduc­tion of a manufacturing knowledge base to this CAM process can provide the most consistent and efficient routing, tooling and machine selection. This knowledge base can also provide Group Technology (GT) information that can be used by the designer and to improve scheduling. Scheduling can be improved by identifying part set-up information and sequencing parts to minimize the tear down and new set-up time for changeovers.

Output from the CAD system can also be processed through a Computerized Process Planning (CAPP) system to create operator instructions. These can be displayed when needed at the operator's work station or via a wireless interface to a portable device. No more lost or obsolete drawings!

This same CAD data can be used by the ERP system. Parts and Bills of Material can be electronically trans­ferred, error free, to the material planning system. With a CAPP system, routing information can also be passed to the production system for capacity planning.

A product that pulls all the information in the manufactur­ing knowledge base together with the other elements mentioned above, achieves DFM via another acronym, CIM (Computer Integrated Manufacturing) or CAM (Computer Aided Manufacturing) or PIM (Product Information Management).

There are many products that provide excellent examples of this state of art integration. Some use artificial intelligence and natural language reporting to simplify their use.

Look for my other articles on Activity Based Costing (ABC), on Reducing Lead-Time and on Statistical Process Control (SPC).