since products are made only after orders are re-
ceived and paid for . And as with mass customization,
there is no unsold finished goods inventory . Finally ,
both 3-D printing and mass customization improve
working capital management, as goods are paid for
before being produced. Due to the nature of the processes and materials,
mass customization and 3-D printing have generally
each been applied to a different range of products. Mass customization has been applied to products
such as computers, watches, windows, shoes, and
jeans. These utilize component parts with a wide
range of materials. In contrast, 3-D printing has
been applied to making prototypes, mockups, re-
placement parts, dental crowns, and artificial limbs
using single materials (see T able 1). 1.2. 3-D printing and injection molding
and cutting-based machinery
This sub-section examines the major advantages of
3-D printing as compared to injection molding or
machining/subtractive technologies. These advan-
tages relate to cost effectiveness and speed. In contrast to injection molding processes that
require costly molds, 3-D printing entails relatively
low fixed costs. Since 3-D printing does not require
expensive tooling, forms, or punches, it is particular-
ly cost effective for very small production runs. This
enables firms to profitably use 3-D printing to eco-
nomically fill custom orders and serve niche markets. In comparison to subtractive technologies, which
use multi-axis cutting machines to carve plastics
and metals to the desired shape, there is less
waste material with 3-D printing: no scrap, milling,
or sanding. According to one source, the waste ma-
terial in metal applications associated with 3-D print-
ing is reduced by 40% in comparison to machining/
subtractive technologies. In addition, 95% - 98% of
waste material can be recycled in 3-D printing (Pet-
rovic et al., 2011). Other sources state that subtrac-
tive technologies can remove as much as 96% of the
raw material when creating a product (Wagner ,
2010). In contrast to injection molding and cutting-
based machinery , in 3-D printing, the variable costs
per part do not decrease with large production runs. 3-D technologies are also able to produce initial
products much more quickly than injection molding
and cutting-based operations since no set-up time is
required. Further , considerable time savings are
incurred when producing revised designs. T able 2 outlines the characteristics of 3-D printing
in comparison to other technologies. The advantages
of 3-D printing include the ability to economically
build custom products in limited production runs, the
ability to share designs and outsource manufacturing,
and the speed and ease of designing and modifying
products. These characteristics lend themselves to
small and medium production run applications such
as mass-customized products, prototypes, replace-
ment parts, medical/dental applications, and bridge
manufacturing. These applications will be discussed
more fully in a subsequent section. T able 2 also lists
the major limitations of 3-D printing that must be
overcome for this technology to be more widely used. 1.3. Additional characteristics of 3-D
printing
3-D printing facilitates outsourcing, as well as the
sharing of designs among designers and users. Soft-
ware programs such as Alibre and Autodesk enable a
person to design a product at home or in the office,
and then send the design via email to a customer . Designs can also be very easily shared in 3-D printing. Consider Nick Starno, a mechanical design engineer
3-D printing: The new industrial revolution 157
T able 1. A comparison of mass customization and 3-D printing
Characteristic Mass Customization 3-D Printing
Manufacturing
T echnology
Based on pre-assembled modular parts in
different combinations or delayed
differentiation.