Design for Manufacturing

1. DESIGN FOR MANUFACTURING (DFM)
Sergio Antonio Salvi
PRODUCT
DEVELOPMENT

2. DESIGN FOR
MANUFACTURING
DFM concept
The Design for Manufacturing (DFM, also called “… for
manufacturability”; cf. Boothroyd, Dewhurst), is a methodology that
extends the recommendations of Design for Assembly (DFA),
an engineering design approach developed in the eighties.
DFM and DFA come from the need to “drive cost”: design a
product so that it is easily manufactured and assembled, means
to save money.
In the field of the so called “design sciences” (born in Europe in
the sixties), this innovation has also generated the concept
“Design for X” (DFX, cf. Ulrich, Eppinger, 2000), in which the
“parameter X” represents the problem that must be solved; in other
words, the “main direction” the product development must follow
(nowadays, for example, Design for X can be “declined” into “Design
for Cost”, “Design for competitiveness” etc.).
PRODUCT
DEVELOPMENT
Sergio Antonio Salvi

3. DESIGN FOR
MANUFACTURING
“Input” and “output”
flows in a productive
system
PRODUCT
DEVELOPMENT
Sergio Antonio Salvi
RAW MATERIALS
AND SEMIFINISHED
MATERIALS
ENERGY
WASTE
FINISHED OR
SEMIFINISHED
PRODUCTS
informaz. services
manpower
(labour)
tools
external
“standard
components”
equipments
PRODUCTIVE
SYSTEM
informat.

4. MANUFACTURING COST
ASSEMBLINGCOMPONENTS GENERAL COSTS
internal
(“already made”)
external
(“to buy”)
to design
(“to make”)
standard
row materials
process
tools
process
tools
labour
labour
support
indirect allocations
DESIGN FOR
MANUFACTURING
product
manufacturing cost
elements
PRODUCT
DEVELOPMENT
Sergio Antonio Salvi

5. MANUFACTURING COST
ASSEMBLINGCOMPONENTS GENERAL COSTS
internal
(“already made”)
external
(“to buy”)
to design
(“to make”)
standard
row materials
process
tools
process
tools
labour
labour
support
indirect allocations

6. DESIGN FOR
MANUFACTURING
DFM principles
Referring to design development strategies, DFM, as mentioned,
happens to be the most important methodology, due to its direct
influence over production’s costs. It contemplates the following
stages (cf. Ulrich, Eppinger, 2000):
(→□)
■ 1. production cost estimate;
■ 2.1 components cost reduction;
■ 2.2 assembly cost reduction (cf. DFA, design for assembly);
■ 2.3 production support cost reduction;
■ 3. evaluation of DFM decisions impact over other factors;
■ 4. production cost recalculation.
PRODUCT
DEVELOPMENT
Sergio Antonio Salvi

7. DESIGN FOR
MANUFACTURING
DFM flows
(→□)
1. production cost
estimate
briefing
4. production cost
recalculation
2.2 assembly cost
reduction
3. evaluation of DFM
decisions impact
2.1 components cost
reduction
2.3 production
support cost red.
yes
project development
no
fair?PRODUCT
DEVELOPMENT
Sergio Antonio Salvi

8. DESIGN FOR
MANUFACTURING
2.1 components cost
reduction:
”NETSHAPE”
MANUFACTURING
■ “Net-shape” manufacturing (in a completely definitive way)
previews the use of construction processes able to a functional
integration of the manufacture goods through its production in only
one stage.
■ Components reduction, which is determined by the net-shape
processes choice, avoids to resort to different technologies and
therefore to materials and to unlike parts management, reducing
at the same time costs of assembly.
■ Technologies that mostly satisfy this principle are those using
moulds, injection moulding and die casting for first.
(→□)
PRODUCT
DEVELOPMENT
Sergio Antonio Salvi

9. DESIGN FOR
MANUFACTURING
2.1 components cost
reduction:
”NETSHAPE”
MANUFACTURING
PRODUCT
DEVELOPMENT
Sergio Antonio Salvi

11. DESIGN FOR
MANUFACTURING
2.1 components cost
reduction: CHOICE
OF THE
ECONOMICAL
SCALE
■ Usually manufacture cost decreases with the increase of
production volume. This happens because the “fixed costs” are
divided from the produced units (“amortization”) and, together,
“variable costs” decrease due to the fact that the company can
justify the access to a bigger scale economy (for example, buy
the material at a lower cost).
■ In a productive system fixed costs are represented, for instance,
from manufacturing equipment (“set up” operations and, in the
most typical case, tools design and construction: cuttings, moulds
and so on).
■ Variable costs (variable along with the production!) are
instead traceable to: materials, machine-hours and so on.
■ In other words: to produce few units it is convenient to have
available processes at low fixed costs and high variable costs; on
the contrary for what concerns high productions.
(→□)
PRODUCT
DEVELOPMENT
Sergio Antonio Salvi

12. DESIGN FOR
MANUFACTURING
2.1 components cost
reduction: CHOICE
OF THE
ECONOMICAL
SCALE
produced units
total cost
machine tool
machining
injection
moulding
mould cost
set up cost
equality point
PRODUCT
DEVELOPMENT
Sergio Antonio Salvi

13. DESIGN FOR
MANUFACTURING
2.1 components cost
reduction:
STANDARDIZING
COMPONENTS
■ The use of standard components in the industrially produced
object is fundamental. Their use means you don’t have to be in
charge of their design (or redesign them) and to produce them (or
produce them again). In the historic scenery of productions oriented
towards design there are even some objects, called “ready-made”,
which were almost integrally built resorting to parts already in the
market.
(→□)
■ External standard components, parts that can be acquired
“through a catalogue”, are produced by specialised suppliers
and traded at a restrained cost, justified by their high production.
Besides, for the same reason, their quality is medium-high.
Examples of this category are the mechanical union elements
(screws, and so on) and some electrical devices (engines, cables
and so on).
■ Unfortunately, often some parts don’t interest this kind of market,
but now and then, a company may decide to design and produce
internal standard components, able to satisfy the needs of
products frequently based on the same platform (wheel rims in
cars, toners cartridges and so on).

14. DESIGN FOR
MANUFACTURING
2.1 components cost
reduction:
STANDARDIZING
COMPONENTS
(“Mezzadro” by A.
and P. Castiglioni;
seat was first applied
to an agricultural
vehicle)
PRODUCT
DEVELOPMENT AND
MANUFACTURING
TECHNOLOGIES
Sergio Antonio Salvi

15. DESIGN FOR
MANUFACTURING
2.1 components cost
reduction: “BLACK
BOX” METHOD
■ “Black box” components acquisition method has origin in the
Japanese automotive industry experience (cf. Clark, Fujimoto,
1991). It was found out that giving only target specifications to
supplier (the product requirements asked for), without an executive
project, generated a process of cost reduction and of quality
increase.
■ This methodology is obviously sustainable when the interaction
with product arquitecture and its components, assembly
interface (and so on) are communicated precisely. Consider also
the importance of putting in competition a series of suppliers.
■ The advantages are significant: an activity of research and
development at zero costs is set up, there is no need for an
internal design of parts, as a consequence the company is
partially taken off responsibility.
PRODUCT
DEVELOPMENT AND
MANUFACTURING
TECHNOLOGIES
Sergio Antonio Salvi

16. OMITTED