At 02:12 PM 12/8/97 -0500, Elaine T. Hunt wrote:
>How common is this for most industry?
>
>""As a general comment on what I have seen thus far, it appears difficult
>to justify the cost of rapid prototype parts unless they are going to
>result in high volume production or are high tech enough to warrant
>special materials and/or have difficult geometry that would be
>expensive to manufacture. Anything that could be used to dispel these
>notions . . . .
I've found that these notions are fairly prevalent in industry, because
when rapid prototyping is viewed only in absolute terms, it is expensive.
However, relative to the business advantage it provides in getting a new
design to market quickly, rapid prototyping can be a wonderful bargain. The
only way to take rapid prototyping out of this boutique situation is to put
an explicit, quantitative price on time for each development project and
use this value of time to make rapid prototyping decisions. Also, any rapid
prototyping used must be closely integrated with the many other tools
available to product developers. Otherwise, the end-to-end business
advantages will not materialize, and management will continue, quite
correctly, to have the "notion" that rapid prototyping is expensive.
Below are three case studies. Each shows how rapid prototyping pays off
handsomely, but only because it is well integrated with the rest of the
rest of the development process and because the development team knows
where it can effectively "buy" time.
These case studies come from the new edition of our book, Developing
Products in Half the Time: New Rules, New Tools, by Preston G. Smith and
Donald G. Reinertsen, John Wiley, 1997, ISBN 0-442-02548-3, US$29.95. The
book also shows how to calculate the value of time. For more information on
the book, please contact me by private e-mail.
Preston G. Smith CMC
New Product Dynamics
Portland, Oregon USA
+1 (503) 248-0900
####################################################
For the most part, this book covers what we call management tools for
accelerating product development, but there are also technology tools.
These include computer-aided design (CAD—both mechanical and electrical),
computer-aided analysis (for example, finite-element stress analysis),
computer simulation (such as is used for circuits simulation), rapid
prototyping (for instance, stereolithography), and product data management
(PDM) software.
Although both the management tools and the technology tools are valuable
for cutting time to market, we place emphasis on the management tools
first, for two reasons. First, we believe that the management tools have
broader potential to shorten all portions of the development cycle, from
product need to first shipment. Second, overemphasis on the technology
tools can result in automating—thus further entrenching—poor management
practices.
That said, the technology tools do have great power to accelerate certain
portions of the development cycle, and any company that is truly interested
in rapid product development uses both technology and management tools.
These excellent companies do not just buy some software and workstations
and install them. Instead, they procure technology solutions to meet
certain identified needs, train their people well in the use of the
technology, and ensure that the technology is well integrated with their
management processes.
To illustrate where the technology tools fit and how they can help, we
provide three case studies. They were chosen to illustrate how several of
the technology tools can work together and be integrated with the
management tools—the kind of solution that provides the greatest
competitive advantage.
Case Study: Senco Products
Senco Products, Inc., is a global manufacturer and marketer of powered
nailers and staplers, and the fasteners they drive. Their SNS45 project
aimed to bolster Senco's leadership position in heavy-duty pneumatic
construction staplers. This project applied recent technological advances
in CAD, QFD, finite-element analysis (FEA), and rapid prototyping. The
project team comprised a Project Engineer, a second engineer, two
designers, a Manufacturing Engineer, a member from tool and die, a buyer, a
marketing member, and the Team Leader, all but two of which were dedicated
full-time. Most were co-located in a 10 meter by 10 meter (30 foot 30
foot) area. This heavyweight team followed much of the guidance in
Chapters 7 and 8. They also employed the financial analysis suggested in
Chapter 2 and kept their trade-off rules in mind by printing them on a
laminated wallet card that each team member carried.
The team collectively used simplified QFD (see Chapter 5) to translate
and prioritize the customers' requirements into a form better suited for
engineering and manufacturing decisions. They accelerated this analysis by
using commercial software that managed the voluminous data associated with
QFD and allowed them to analyze several alternative formulations quickly.
Beyond the anticipated advantages of their QFD analysis, the QFD data paid
off later when a Senior Sales Manager forcefully protested the team's
design approach for loading fasteners. The Manager of Product Development
and Team Leader, Scott Allspaw, and Project Engineer, Jack Schloemer,
worked to prevent the issue from derailing the team by using the QFD and
market research analyses to solidly support their design approach. The QFD
analysis software supported them well here, because they were able to
recast the results quickly to shed light on the fastener loading issue.
Project Engineer Schloemer faced a tough decision regarding the CAD
system. After the project began, an upgrade package became available that
would provide more capability, but would require training for the
designers. He pondered, "Should we spend time (and money) to be more
effective later?" He concluded and convinced the team that the CAD upgrade
would not only bring benefits to this team, but position the company better
for future projects. Note that usually it is better not to change the CAD
system after the project has begun to avoid unnecessary disruptive change
during a project. In this case, however, the new CAD package was
available early enough to make such a change feasible. Team Leader Allspaw
was skeptical initially, seeing a clear parallel between CAD upgrades and
the disastrous creeping elegance phenomenon that afflicts product features.
However Schloemer did not let the upgrade affect the schedule; as Allspaw
puts it, "He had the designers on the airplane headed for training before
the final signature was on the upgrade approval."
The Project Engineer's wisdom also paid off on one part that presented
subjective ergonomics and feel issues that affected the product's
differentiation in the marketplace. He helped the team to retain focus and
reach closure on the design so the tooling could be finalized. To do this,
he worked with the designers in helping them leverage the CAD system,
without becoming enamored with the CAD's ability to "optimize" the design.
Schloemer assessed the amount of time this part should receive compared
with the balance of tasks required to complete the entire design. With the
flexibility of the new CAD system and the creativity of an outside
industrial designer, the possibilities were endless. The team simplified
the part, made some decisions on aesthetics, and moved on.
Another part was to be investment cast. Previously, such prototypes for
functional confirmation were machined from solid stock. As this was
clearly time inefficient, the team turned to stereolithography (a rapid
prototyping technique). In addition to the primary advantages offered by
rapid prototyping of having a part that could be touched and felt, the
SNS45 project took the technology further. The team shared the rapid
prototype part with the foundry, which was able to give instantaneous
feedback on manufacturability improvements. Then the rapid prototype was
used as a pattern for functional prototype parts.
The Buyer, Tom Kent, and Manufacturing Engineer, Dan Reed, uncovered an
opportunity to fundamentally change the way the company acquired prototype
aluminum castings. Reed explains, "We modemed the CAD file (without
tolerance details) to a stereolithography service bureau, who in turn
supplied a prototype core and shell to the pattern maker. The pattern
maker then constructed a mold for the foundry, which poured functional
aluminum parts. The team used these parts to build staplers for initial
testing. This accelerated means of making parts shaved 10 to 14 weeks off
of Senco's normal approach. And nobody even asked for a toleranced print!"
Allspaw observes that this opportunity to consider making parts
differently emerged from the proximity and dedication of the Buyer, the
Manufacturing Engineer and the Designer. Furthermore, because the team
wasn't required to seek management approval before proceeding, the decision
to pursue this new method took place in a team meeting lasting less than an
hour.
The SNS45 team decided to use FEA as an engineering tool to locate
high-stress areas in one of the most critical parts on this new tool. This
part had to be strong enough to withstand abuse and contain air pressure.
The team saw FEA as a way to get this information quickly and hopefully
shorten testing time for this component. Senco was in the process of
training an employee in FEA analysis, so team members decided to use this
part as a training exercise that would also give them the stress
information they needed. But the FEA model of the component turned out to
be more complex than anticipated. As a result of this complexity, it took
almost three weeks to complete the analysis. They did get a robust design
right the first time, but the time savings was not as great as it might
have been had the team given the job to an expert in this field. Senco
learned that the decision to use FEA requires careful consideration and
that an experienced analyst is needed to gain the most benefit from FEA.
As the SNS45 team integrated many of these technology tools, they sent CAD
files to several suppliers to obtain parts for testing and prototype tool
builds. Often, these files first had to be translated to another format
(e.g., DXF, IGES) and then sent to the supplier via modem. Sometimes
suppliers have trouble using such files and must make certain corrections
before they can begin making parts or tooling. Senco has learned that
these problems can be minimized by early involvement of their CAD
Administrator with the suppliers. They identify differences in their
systems and file format requirements far in advance. Then they send sample
files back and forth for evaluation and to work out the bugs, off of the
critical path. This approach helps ensure that the time saved by these new
tools is not offset by delays encountered in file transfer and translation.
This case study reveals a strong inclination toward learning from past
projects at Senco. The company applies the continuous process improvement
tools described in Chapter 15. Consequently, cycle-time continually
decreases, as illustrated in Figure 1-3.
Case Study: Lathrop Engineering
Lathrop Engineering specializes in the rapid development of new products
for client companies. A major pacemaker manufacturer approached them to
develop an instrument used to set up the pacemaker and adjust it after it
has been implanted in a patient. The client urgently needed a
next-generation instrument to preserve its core market for the pacemakers
themselves.
To start design, the team had to understand how users interact with the
instrument and how frequently they use various interfaces, such as the
touch screen, modem connections, and built-in printer. The team generated
some preliminary solid models of the system configurations under
consideration. Then the multi-disciplinary team discussed and refined
positions of the user interfaces and internal components. This was
important because team members needed to minimize the instrument's height
without compromising the vital, sensitive communication link between the
instrument and the implanted pacemaker. Concurrently, Rick Emerson, the
Industrial Designer on the project, developed hand sketches and foam-core
models of the concepts. The team then converged on the form and look of
the instrument. In a little over a month this cross-functional team
synthesized an overall shape, a user interface configuration, and a layout
of the key internal components, setting a strong basis for the detailed
design work in the next phase. Notice how they mixed their high-tech solid
modeler and low-tech sketch pad to exploit the power of each medium to
reach certain decisions quickly.
During the detailed-design phase the team reviewed progress on the CAD
model every week. This weekly review allowed them to make design
corrections before designers wasted time going down unfruitful avenues.
For example, they recalled that the instrument's carrying handle had been a
problem in previous models. So they ran a finite element analysis, which
took just a few days, to assure that the handle design would not fail.
This saved weeks of prototyping and testing time. The analysis allowed
them to identify areas of high stress and even to eliminate some material
in low-stress areas.
Thermal performance of the system was critical, due to the thermal
printer, which generated heat, being packed closely with the hard disk,
which would not work reliably at high temperatures. They started with
classical thermal analysis, to get an understanding of the important
thermal parameters. The tool of choice here was Mathcad, a relatively
simple software package that let the engineer set up the natural convection
and fan-forced airflow calculations and adjust them easily as the
configuration changed. This level of analysis showed that using even a
small fan gave reasonable safety margins, but the system would not have met
specifications without a fan. This relatively simple but flexible
technique eliminated the need for time-consuming and complex FEA analysis
and thermal testing–redesign iterations.
The solid modeling capabilities of the CAD system proved to be a
time-saver for Steve Wilson, one of the engineers on the project. He could
easily monitor the design's mass properties and check for interferences as
the design team worked to stuff all of the required electronics into the
small interior space. These interference checks before parts were made
saved several weeks of modifications later when the initial prototypes were
built.
Several technology tools helped Lathrop integrate suppliers into the
project. Early in the design phase the team contacted about 20 molders as
potential suppliers of the plastic parts. Molders were given files of the
plastic parts to create preliminary budgets for tooling. The suppliers
were able to bring the files up on their CAD systems, which accelerated and
improved the quality of their tooling quotations. Before the design was 80
percent complete Lathrop selected the final molder, and this molder's
involvement during the design phase cut weeks off the development cycle.
When the CAD model was complete, final CAD files were sent to the molder
and suppliers of the non-plastic parts to start the prototype procurement
process. First, the rapid prototyping house used the CAD files to create a
stereolithography model of the instrument, which took only a week. This
model was used to verify that all of the components fit and to give the
electronics subteam a platform to start system integration.
In the past it would have been risky to go straight to production tooling
on a project of this complexity, but due to the solid model's database and
the stereolithography prototype the team decided to commit to production
tooling in the prototype phase. This decision saved the additional time
needed to create both prototype and production tooling, and also enabled
early pre-validation testing. To fill the gap from the one-off
stereolithography prototype to the production injection molds, 15 urethane
cast prototypes were fabricated in about two weeks. Marketing used some of
these units for user feedback, Manufacturing started planning the
manufacturing process with them, and Engineering built functional units to
use for software development.
After prototype testing some changes had to be made to the design. These
changes resulted from EMI (electromagnetic interference) testing and from
focus group feedback. Most of the changes were minimal and none of the
plastic injection molds had to be scrapped. This project was completed in
just five months, from the start of the initial concept to availability of
pre-production models (these models are used for clinical trials and other
regulatory and safety approvals that can take up to a year for devices of
this type).
Case Study: BroadBand Technologies
BroadBand Technologies, Inc., provides equipment to advance telephone
network technology by adding broadband digital services to residential
dialtone lines. Our last case study ended with some EMI issues, but the
magnitude of the electronics and the frequencies involved in BroadBand's
products makes EMI a major concern. Let's see how the company kept EMI
problems off of its critical path by integrating technology tools into the
development process.
Early in a high-speed multiplexer project the team had a mechanical design
concept, but wanted to do early verification testing to ensure the approach
would work. The concept included a rack-mountable sheet-metal card cage
and 30 circuit cards plugging into a backplane. Four multiplexers would be
stacked in a seven-foot equipment rack with a fan to force cooling
vertically. The need for cooling created a conflict with the need to
control EMI. The top and bottom panels of the card cage had perforations
that were large enough to allow cooling but small enough to minimize EMI.
The front of the card cage presented even more challenges due to
penetrating fiber cables connecting to the cards and alarm indicators that
had to be visible. These requirements led to individual, electrically
conductive faceplates on each circuit card. In order to minimize cost, the
faceplates were injection-molded parts with electroless copper/nickel
plating. Due to the importance of the program and the expense of the
faceplate mold, BroadBand needed to verify early that its design would
provide adequate EMI shielding.
The developers sent CAD files of the faceplates to a supplier that
produced a master part using stereolithography. From this, they made a
rubber mold, then they cast urethane faceplates. These were painted with
copper paint to simulate electroless nickel/copper plating.
Simultaneously, they sent CAD files for the card-cage parts to a
sheet-metal supplier. Notice that all of this was done directly from the
solid model without any drawings or tolerancing. Elimination of the
detailed drawings reduced time to prototypes by a month.
EMI test lab results indicated that the design would provide adequate
shielding with only minor design changes. These early test results
increased confidence in the design approach, so BroadBand committed to
faceplate hard tooling. BroadBand continued to leverage use of the
faceplate CAD files by selecting a tooling supplier that could build the
injection molds from the CAD database without drawings. This allowed the
tool-building process to start three to four weeks earlier than if detailed
drawings had been required. Detailed drawings were eventually created, but
they were done off the critical path. BroadBand conducted a final EMI test
with hard-tooled parts, and the design passed without further modification.
This archive was generated by hypermail 2.1.2 : Tue Jun 05 2001 - 22:40:52 EEST