//SYS21///INTEGRAS/B&H/PRS/FINALS_07-05-03/0750654376-CH002.3D – 24 – [19–34/16] 13.5.2003 7:43PM
.
Production quantity per annum – The number of components to be produced to account for
the economic feasibility of the manufacturing process. The quantities specified for selection
purposes are in the ranges:
Very low volume ¼ 1–100
Low volume ¼ 100–1000
Medium volume ¼ 1000–10 000
Medium to high volume ¼ 10 000–100 000
High volume ¼ 100 000 þ
All quantities.
Due to page size constraints and the number of processes involved, each manufac-
turing process has been assigned an identification code rather than using process
names, as shown at the bottom of Figure 2.2. There may be just one or a dozen
processes at each node in the selection matrix representing the possible candidates for
final s electi on.
As seen in Figure 1.11, there are many cost drivers in manufacturing process selection,
not least component size, geometry, tolerances, surface finish, capital equipment and labor
costs. The justification for basing the matrix on material and production quantity is that
it combines technological and economic issues of prime importance. Many manufacturing
processes are only viable for low-volume production due to the time and labor involved.
On the other hand, some processes require expensive equipment and are, therefore,
unsuitable for low production volumes. By considering production quantities in the early
stages, the process that will prove to be the most economical later in the development
process can be identified and selected. The boundaries of economic production, however,
can be vague when so many factors are relevant, therefore the matrix concentrates rather
more on the use of materials. By limiting itself in this way, the matrix cannot be regarded
as comprehensive and should not be taken as such. It represents the main common
industrial practice, but there will always be exceptions at this level of detail. It is not
intended to represent a process selection methodology in itself. It is essentially a first-level
filter. The matrix is aimed at focusing attention on those PRIMAs that are most appro-

assembly system selection. The reader interested in this topic can find more information in
References (2.7–2.9).
Prior to the selection of an assembly technology, a number of activities should be under-
taken and factors considered, some of which also help drive the final quality of the assembly:
.
Business level – Identification and availability of assembly technologies/expertise in-house,
integration into business practices/strategy, geographical location and future competitive
issues, such as investment in equipment.
.
Product level – Anticipated lead times, product life, investment return time-scale, product
families/variants and product volumes required.
.
Supplier level – Com ponent quality (process capability, gross defects) and timely supply of
bought-in an d in-house manufactured parts.
The final point is of particular importance. A substantial proportion of a finished product,
typically, two-thirds, consists of components or s ub-assemblies produced by suppliers (2.10).
The original equipment manufacturer is fast becoming purely an assembler of these bought-in
parts, and therefore it is important to realize the key role suppliers have in developing products
that are also ‘assembly friendly’. Consideration must be given to the tolerances and process
variability associated with component parts from a very early stage, especially when using
automated assembly technologies, because production variability is detrimental to an assembly
process.
From the above, a number of drivers for assembly technology selection can be highlighted:
.
Availability of labor
.
Operating costs
.
Production quantity
.

Flexible (programmable, robots) [6.2]
.
Dedicated (special purpose) [6.3].
Upon candidate selection, further reference is made to the individual PRIMAs for each
assembly system type in order to fully understand the technical and economic implications of
the final decision and explore system variants available. This is pa rticularly advantageous
when Figure 2.3 shows that a set of requirements is on the boundary of two assembly system
types.
Fig. 2.3 Assembly system selection chart.
26 Selecting candidate processes
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2.3.3 Joining process selection
There is extensive evidence to suggest that many industrial products are designed with far too
many parts. DFA case studies indicate that in many designs large proportions of excess
components are only used for fastening (2.11). These non-value added components increase
part-count and production costs without contributing to the product’s functionality. In many
cases, inco rrect joining processes are used due to a lack of knowledge of such factors as
availability, cost and functional performance of alternatives. As with primary and secondary
manufacturing processes, selecting the most suitable joining process greatly influences
the manufacturability of a design, but the selection of the joining technology to be used can
also greatly influence the assemblability of a design. The method chosen can also have
a significant influence on the product architecture and assembly sequence and it is well
known that complicated joining processes lead to incorrect, incomplete an d faulty assemblies
(2.12).
Selecting the most appropriate joining technique requires consideration of many factors
relating to joint design, material properties and service conditions. During the selection
procedure the designer is required to scrutinize large quantities of data relating to many
different technologies. Several selection methods exist for the selection of the process variants
within individual joining technologies. However, selecting the most appropriate technology
itself remains a design-orientated task that often does not get the attention it deserves. It can

a common factor is used, based on technology and process. Technology class refers to the
collective group that a process belongs to, for example, welding or adhesive bonding. The
process class refers to the specific joining technique, for example, Metal Inert-gas Welding
(MIG) or anaerobi c adhesive. Each process is derived from a particular fundamental
technology providing a means for classification. From this, the joining processes have been
divided into five main categories: welding, brazing, soldering, mechanical fastening and
adhesive bonding.
Technical classes can be separated into sub-categori es based on distinct differences in
underlying technology. Although the basic premise of all welding processes is the same,
specific techniques differ considerably due to the particular processes involved in generating
heat and/or enabling the fusion process. This can be used as a means of classifying sub-
sets. Both brazing and soldering have a number of different processes, hence they have
been split into two sub-sets. Mechanical fasteners can be divided in two ways, by group
technologies and degree of permanence. The latter has been chosen as it relates to the
functionality of the fastener in service and therefore product requirements. Due to the large
number of specific adhesives, which in many cases are exclusive to the producer, adhesive
bonding has been viewed from a generic level, therefore, only the adhesive group can be
selected.
Joining process selection criteria
In order to select the most appropriate joining process, it is necessary to consider all processes
available within the methodology. As technology specific selection criteria tend to be non-
transportable between domains, evaluating the merits of joining processes that are based on
fundamentally dissimilar technologies requires a different approach. Differentiating between
technology classes and process classes requires the comparison of specifically selected
parameters. In order to evaluate a joint , consideration must be given to its functional,
technical, spatial and economic requirements. A review of important joining requirements
has identified a number of possible selection criteria, as shown in Figure 2.4 and discussed
below.
.
Functional – Functional requirements define the working characteristics of the joint. The

ment of detailed geometry, using geometry as a selection criterion would be contradictory.
Material thickness has already proven to be a successful criterion in other selection
methodologies, and the suitability of joining processes is easily classified for different
thicknesses of material.
.
Economic – The economics of joining processes aligns the design with the business needs
of the product. Economic considerations can be split into two sections: tooling and
Fig. 2.4 Classification of joint requirements.
PRIMA selection strategies 29
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product. Tooling refers to the ease of automation, availability of equipment, skill
required, tooling requirements and cost. Product economics relate to production rates
and quantity. These business considerations are driven by the product economics as they
determine the need for tooling and its complexity, levels of automation and labor
requirements. Production rate and quantity are very closely linked. They can both be
used to determine the assembly speed and the need for and feasibility of automation.
However, as the selection methodology is to be used in the early stages of product
development it is more likely that quantity will be known from customer requirements
or market demand.
In order for the selection methodology to be effective in the early stages of design appraisal,
the chosen parameters must apply to all joining processes. Also, it is essential that the
parameters relate to knowledge that is readily available and appropriate to the level of
selection. Having reviewed the requirement against the joining processes, four selection
parameters have been chosen for initial stages of the methodology:
.
Material type – Accounts for the compatibility of the parent material with the joining
process. A large proportion of the materials used in engineering manufacture have been
included in the selection methodology, from ferrous alloys to precious metals. In situa-
tions involving multiple material types the selection methodology must be ap plied for
each.

Joining process selection matrix
The joining process selection methodology is based on the same matrix approach used for
manufacturing process selection. Again, due to page size constraints and the number of
processes to be detailed, each process has been assigned an identification code rather than
using process names. The key to the joining processes used in the matrix is shown in Figure 2.5
together with the relevant PRIMA number, where information can be found regarding
that individual process or joining technology. Due to size constr aints, the joining process
selection matrix is divided into two parts; Figures 2.6(a) and (b) toget her show the complete
matrix.
The matrix representation of the selection technique provides an intuitive way of navigating
a large quantity of data. This makes the selection process simple and quick to use. Supporting
the selection matrix with design advice through the use of the PRIMAs completes the
Fig. 2.5 Key to joining process PRIMA selection matrix.
PRIMA selection strategies 31
//SYS21///INTEGRAS/B&H/PRS/FINALS_07-05-03/0750654376-CH002.3D – 32 – [19–34/16] 13.5.2003 7:43PM
IRONS
THIN
£3mm
STEEL
(carbon)
STEEL
(tool, alloy)
STAINLESS
STEEL
COPPER
& ALLOYS
ALUMINIUM
& ALLOYS
MAGNESIUM
& ALLOYS

[W2][W3]
[W9][W11]
[W13][W14]
[W15][B1]
[W3][W7]
[W9][W10]
[W13][W15]
[F20]
[F19][F20]
[F19][F20]
[W2][W3]
[W6][W8]
[W9][W11]
[W13][W14]
[W15][B1]
[W2][W3]
[W9][W11]
[W13][W14]
[W15][W17]
[B1]
[W9][W10]
[W13][W15]
[W17]
[F20] [F19][F20] [F19][F20]
[W1] [W1]
[S1][S8]
[W1][W2]
[W3][W9]
[W13][W14]
[B1]

[W16]
[W17][B1]
[W13]
[W15]
[W16]
[W17]
[F19][F20]
[F23]
[F19][F20]
[F23]
[W3][W9]
[W11][W13]
[W14] [W15]
[W16][W17]
[B1]
[W9] [W13]
[W15][W16]
[W17]
[F20]
[F19][F20]
[W2][W3]
[W8][W9]
[W11] [W13]
[W14][W15]
[B1][B6]
[W2][W3]
[W9][W11]
[W13][W14]
[W15] [W17]
[W16][B1]

[W13]
[F19][F23] [F19][F23]
[W3][W9]
[S1][S8]
[F23] [F23]
[W3][W8][W9]
[W13][W14]
[B1][B6]
[W4][W3]
[W9][W13]
[W14]
[W13]
[F23] [F23]
[S1][S8]
[F23] [F23]
[W16]
[W17][B2]
[B4]
[W16]
[W17][B4]
[W8][W11]
[W13][W14]
[W19][B2]
[B4][B6]
[W11][W13]
[W14][W16]
[W17][W19]
[B2] [B4]
[W13][W16]
[W17]

[W1][W2]
[W8][W11]
[W13][W14]
[W19][B2]
[B4][B6]
[W1][W2]
[W11][W13]
[W14][W19]
[B2][B6]
[S2][S6][S8]
[W8][W13]
[W14][B2]
[B4][B6]
[W4][W13]
[W14]
[W13]
[S2][S6][S8]
[W18][B2]
[B3][B4][B8]
[B2][B3]
[B4][B8]
[W8][W11]
[W13][W14]
[W18][W19]
[W20][B2][B3]
[B4][B5][B7]
[B8][F7] [F9]
[W4][W13]
[W16][W17][B3]
[B8]

[F11][S3]
[S2][S3][S4]
[S5][S7][S9]
[W18] [W19]
[W20][B2]
[B3][B4][B5]
[B8][F7][F9]
[W4][W18]
[W20][B2]
[B3][B8]
[B3][B8]
[W4][W8]
[W11][W14]
[W18][W19]
[W20][B2][B3]
[B4][B5][B7]
[B8][F7][F9]
[W4][W11]
[W14][W19]
[B2][B3][B8]
[B8]
[S2][S3][S4]
[S5][S7][S9]
[W8][W14]
[W18][W20]
[B2][B3]
[B4][B8]
[W4][W14]
[W18][W20]
[B3][B8]

[W18][W20]
[W21] [B3]
[B8][F7][F9]
[W4][W18]
[W20][W21]
[B3][B8]
[W21][B3]
[B8]
[W4][W18]
[W20][W21]
[B3][B8][F7]
[F9]
[W4][W21]
[B3][B8]
[W18][W20]
[B3][B8]
[W18][W20]
[W21][B3]
[B8]
[W21]
[S3][S9]
VERY LOW
1 TO 100
LOW
100 TO 1,000
LOW TO MEDIUM
1,000 TO 10,000
MEDIUM TO HIGH
10,000 TO 100,000
HIGH

[A4][A5][A8]
[A10]
[F1][A1][A2]
[A4][A5][A10]
[F1]
[F13][A9] [F12][F13] [F12][F13]
[F15][F17]
[F21]
[F15][F17]
[F21]
[F15][F17]
[F21]
[W5][W12]
[F1][F5][F6]
[F8][F10]
[A4]
[A10]
[W12][F1]
[A4] [A10]
[F1]
[F13][A9]
[F14]
[F12][F13] [F12][F13]
[F15][F17]
[F21]
[F15][F17]
[F18[F21]
[F15][F17]
[F18[F21]
[W12][F2]

[F1][F2][A2]
[A4][A5][A7]
[A10]
[F1][F2]
[F13]
[A9]
[F14]
[F12][F13] [F12][F13]
[F15][F16]
[F17][F21]
F[15][F16]
[F17][F18]
[F21]
[F15][F17]
[F18][F21]
[W12][F1]
[F2][A1][A4]
[A5]
[W12][F1]
[F2][A4]
[A5]
[F1][F2]
[F13][A9]
[F16][F21]
[F16][F18]
[F21]
[F18][F21]
[W12][F2]
[F10][F14]
[W12][F2] [F2]

[B6]
[W4][W11][W13]
[W14][W16]
[W17][W18]
[W19][W20]
[B2][B3][B4][B8]
[S3] [S9]
[S1]
[S1]
[S6]
[S3]
[S3]
[S1]
[S1]
[S3] [S9]
[F12][F13] [F12][F13]
[F14]
[W19]
[W19]
[F11] [F11]
[F11] [F11]
MATERIAL &
THICKNESS
QUANTITY &
PERMANENCE
MED.
3 to
19mm
THICK
³19mm

THIN
£3mm
MED.
3 to
19mm
THICK
³19mm
THIN
£3mm
MED.
3 to
19mm
THICK
³19mm
THIN
£3mm
MED.
3 to
19mm
THICK
³19mm
THIN
£3mm
MED.
3 to
19mm
THICK
³19mm
THIN
£3mm

CERAMICS
REFRACTORY
METALS
PREC-
IOUS
METALS
DISSIMILAR
MATERIALS
[W1] [W1]
[S1][S8]
[F23]
[F23]
[W2][W3]
[W6][W8]
[W9][W11]
[W13][W14]
[W15]
[W2][W3]
[W9][W11]
[W13][W14]
[W15]
[W9][W10]
[W13][W15]
[S1][S8]
[F20] [F20] [F20]
[W2][W3]
[W9][W13]
[W14]
[W2][W3]
[W9][W13]

[W2][W3]
[W8][W9]
[W11][W13]
[W14][W15]
[B6]
[W2][W3]
[W9][W11]
[W13][W14]
[W15][W16]
[W9][W13]
[W15]
[S1][S8]
[F20] [F20] [F20]
[W2][W3]
[W9][W13]
[W14]
[W2][W3]
[W9][W13]
[W14]
[W3][W9]
[W13]
[W22] [W22] [W22]
[W2][W3]
[W8][W9]
[W13][W14]
[B1]
[W2][W3]
[W9][W13]
[W4] [W1][W2]
[S1][S8]

[S2][S8]
[W2][W8]
[W11][W19]
[B2]
[W2][W11]
[B2]
[S2][S3][S6]
[S8][F11]
[F11]
[F22] [F22]
[W8][W11]
[W14][W18]
[W20][B3]
[B4][B5][B7]
[B8][F9]
[W4][W11]
[W14][W16]
[W18][W20]
[B3][B8]
[W4][B3][B8]
[S2][S3][S4]
[S5] [S7][S9]
[W8][W14]
[W18][W19]
[W20][B3]
[B4][B7][B8]
[W4][W14]
[W18][W19]
[W20][B3]
[B8]

[W20][W21]
[B3] [B8]
[W4][W21]
[B3][B8]
[S3][S9]
[W18][W20]
[W21][B3]
[B8]
[W4][W18]
[W20][W21]
[B3][B8]
[W21][B3]
[B8]
[F7]
[F11] [F11]
[F7]
[F11]
[W18][W21]
[B8]
[W4][W18]
[W21]
[W20][W21]
[B3][B8][F7]
[F9]
[W4][W20]
[W21][B3]
[B8]
[W4][B3][B8]
[F11] [F11]
VERY LOW

[F21]
[F15][F17]
[F18][F21]
[F15][F17]
[F18][F21]
[W5][F2][F3]
[F1][F4] [F6]
[F10] [A2]
[A4][A8]
[A10]
[F2][F3]
[F1][F10]
[A2][A4][A8]
[A10]
[F1][F2]
F3][A4]
[A10]
[A9]
[F17][F21]
[F23]
[F17][F18]
[F21] [F23]
[F17][F18]
[F21] [F23]
[F2][F3][F4]
[F10][A2][A4]
[A7][A8]
[F2][F3][A2]
[A4][A7][A8]
[F2][F3][A7]

[F21]
[F15][F17]
[F18][F21]
[F15][F17]
[F18][F21]
[F1] [F1] [F1]
[F13] [F12][F13] [F12][F13]
[F18][F21] [F18][F21]
[W5][F1]
[F8][A4]
[F16][F17]
[F18][F21]
[W5][W12]
[F1][F2][F5]
[F6][F10]
[W12][F1]
[F2][F10]
[F1]
[F13][F14] [F12][F13] [F12][F13]
[F15][F16]
[F17][F18]
[F21][F23]
[F15][F16]
[F17][F18]
[F21][F23]
[F15][F17]
[F18][F21]
[F23]
[W2][W8]
[W9][W11]

PERMANENCE
NP
SP
P
NP
SP
P
NP
SP
P
NP
SP
P
NP
SP
P
NP
SP
P
THIN
£3mm
MED.
3 to
19mm
THICK
³19mm
THIN
£3mm
MED.
3 to

³19mm
THIN
£3mm
MED.
3 to
19mm
THICK
³19mm
THIN
£3mm
MED.
3 to
19mm
THICK
³19mm
THIN
£3mm
MED.
3 to
19mm
THICK
³19mm
THIN
£3mm
Note - The joining process PRIMA selection matrix cannot be considered as comprehensive and should not be taken as such. It represents the main common industrial practice, but there will always be
exceptions at this level of detail. Also, the order in which the PRIMAs are listed in the nodes of the matrix has no significance in terms of preference. Dissimilar metals also accounts for joining metals with coatings.
Fig. 2.6 (b) Joining process PRIMA selection matrix ^ part B.
PRIMA selection strategies 33