By Gerald Davis
Design for manufacturing (DFM) is an im- portant part of product development. Fab- ricators have strong abilities in DFM, yet
a common lament is that their wisdom is sought
only after the “final” design has been found to be
wanting.
In my precision sheet metal job shop experience,
not many of the customers knew what to ask for
with regard to DFM. They certainly knew they wanted great parts at a lower price. My shop didn’t volunteer much unless asked; we were not engineers. In
retrospect, it would have been ideal to spend more
time in meetings with my job shop customers as
a member of their design team. With so many demands for time, it is a necessity to pick the battles
that can be won.
Design Against Manufacturing?
Here’s a CAD Tip: Do not ever design against
manufacturing.
By design for manufacturing, we’re talking about
optimizing a design for a specific process. For example, injection molding is different from chemical
milling, and both of those processes are different
from additive manufacturing. All have a different
impact on design.
The goal of DFM is to match a product’s function
and demand with methods and materials that are
best suited for fabrication. “Best suited” usually aspires to mean “most efficient” use of labor and material. Sometimes, schedule—that is to say cost of
opportunity—might be defined best as “on hand.”
For a DFM consultant, a moving target is something
to expect and to embrace.
A typical DFM review meeting emphasizes rate of
production and covers the what, why, when, and
who. As a contrast, an industrial design (ID) review
meeting has a different purpose and might focus on
invention, inspiration, sensation, or perhaps ideal
operation.
The “why” of the users’ experience is the result of
decisions made by ID. We wryly note that ID is generally pleased with their work. (Thank you!) The decision to carve from billet or stamp from sheet is not
something ID wants to own or perhaps even to discuss. However, DFM can’t make the decision without understanding ID’s overall goals for the product.
Business decisions about quantity and schedule
for manufacturing are subject to change based on
end users’ demands. The release of a new product
requires some guesswork. Management is always
conflicted by low unit price and no idle inventory;
they want both. After agonizing over cash flow,
management’s role in DFM is to set a target range on
batch size and order frequency. Prevailing circum-
stances regarding material availability and utiliza-
tion set the final batch size and shipping schedule.
DFM combines business decisions with design aspirations to come up with how it’s made. As a vital
part of the development team, the purchasing department ultimately assigns “who” for the fabrication of the product.
Becoming a Team Player
DFM thrives with good understanding of the prod-
uct’s intended function as well as its production
schedule. Since launching my practice in 2004, I
have worked as a DFM consultant on a variety of
product development teams. Sometimes being a
team player requires first being a team organizer.
Roles depend upon the circumstances of the busi-
ness. In all cases, my ability to incorporate sugges-
tions from competing interests has led to success. I
try to radiate positive attitude; I want to learn from
the team what constitutes the ideal before any com-
mitment is made to design.
By the same token, I don’t make idle suggestions.
I’m prepared with facts and figures. If I said “wood,”
it would reflect my considerations of the impact on
function, aesthetic value, cost of ownership, and
speed of distribution.
I’ve met a few industrial designers. Most are ad-
ept at delegation. That is to say, if someone else is
responsible for resolving a detail, they will not inter-
fere. However, if ID has taken ownership of a topic,
then the utmost deference to their judgement is
prudent. For example, if they want a chrome-like
appearance, do not suggest wood as the first option.
The manufacturing department takes ownership
of every detail on drawings. Like ID, they don’t like
to have their stuff messed with. Their policies for
revision control and document management are vi-
PRECISION MATTERS
Read more from Gerald Davis at www.thefabricator.com/author/gerald-davis
Navigating the design for manufacturing
and industrial design worlds
DFM works best when it is part of the design team, not an afterthought
The ultimate measurement
scorecard is a schedule
and budget that define
the success or failure
of the product.
If the product is too
expensive or is not
available then there
are no sales.
Figure 1
This is a preview of the design for manufacturing challenge that will be discussed in the January 2018 column:
How to get this concept coffeemaker model ready for manufacturing.
