Understanding current process capabilities means more than knowing which
processes an organization is capable of utilizing in manufacturing its products.
A thorough knowledge of process capabilities is achieved only by effective
process measurement, process control, and the application of resulting data to
future processing. Data must be properly documented, and the documentation
updated regularly. The organization must ensure that this process capability
documentation is utilized in the design and processing of future products as
well as in the optimization of the manufacturing sequence for current products.
Management commitment to a thorough understanding of process capabilities and
the effective application of that knowledge to both current and future
processing is paramount to enhancing producibility.
Process capabilities must be determined for both the organization itself and
for its key suppliers. In general, the depth of understanding required for the
organization's processes is far greater than that required for suppliers'
capabilities. However, for highly complex components or subassemblies which
require precise, difficult processing, an organization must ensure that its
suppliers have a similar commitment to the requisite understanding and control
of its respective processes.
It is tempting for an organization committed to a more complete understanding
of its process capabilities to require that a similar level of knowledge be
achieved for every process. This, however, is neither required nor economically
prudent. Monitoring and tightly controlling every process is not crucial. One of
the most important steps in determining process capabilities is performing a
tradeoff analysis which identifies the level of understanding and control
required for each process. This analysis should identify which processes must be
fully understood, monitored, and controlled and which processes are perhaps less
complex or less critical to the manufacture of product and therefore require a
less complete understanding. Oftentimes, an organization's first cut at a
tradeoff analysis might target complex and specialized processes. However, the
complexity or specialization of a process does not necessarily determine its
need for a more in-depth process understanding. An organization might utilize a
very complex and specialized process in the manufacture of its products;
however, the tolerance requirements of those products may be lax enough to
enable less rigorous process monitoring and control. In general, any process
which is critical to the organization's product lines and which requires the
optimization of a number of process parameters must be more thoroughly
understood and controlled than those less important processes. These critical
processes might be those that enable an organization to be the supplier of
choice for a certain product line or those that permit the company to compete
more successfully against its competitors. They may be those considered by the
company to be its niche or its core competency processes. Certainly, they must
be those that, without effective process understanding and control, are
responsible for or contribute to a product not meeting the customer's
performance, cost, and schedule requirements.
From a risk management standpoint (1.3 ), an
additional consideration in identifying the level of process capability
understanding and control required is process maturity. A technology can be
defined as mature if it has been demonstrated on the factory floor and
successfully used to manufacture a similar product in the past. Processes that
are not mature usually require additional studies and statistical analyses to
ensure that the capability is fully understood and defined prior to its use in
the production of a product.
The understanding of process capabilities must be both general and product
specific. Although a large number of different products might require the use of
a particular process during their manufacture, the level of understanding and
control of the process will likely vary on a product-by-product basis as well.
It is precisely this reason that determining process capabilities is both an
enterprise-wide and a product-specific step in achieving producibility
throughout the organization.
Process capability documentation, or guidelines, defines the manufacturing
capabilities and delineates the limits and rules associated with each. This
documentation can be in the form of guideline handbooks, a process capability
library, a database management system, or a knowledge-based software
application. Regardless of the form of the guidelines, process capability data
must be integrated into the organization's design and engineering procedures and
utilized by product IPTs in the development of their products.
Process capability guidelines should contain information on process
capabilities and constraints (i.e., products, design features, tolerances,
materials); optimum process parameters; and data on overall manufacturing
capability such as resource availability (i.e., parts, materials, and production
systems) and production capacity (low versus high volume as well as part and
Determining process capability must be looked at as a continuous and not a
one-time effort. The guidelines must be updated regularly to benefit the
producibility of future products. This is particularly important with the
introduction of a new product line. Taking the lessons learned from new product
manufacture and feeding the process parameters and constraints into process
capability documentation ensure that the organization is most effective in
producing similar products in the future. Additionally, the organization might
find that processes developed or optimized for a new product might successfully
be substituted in the manufacture of older products with resultant increases in
product performance, decreases in product cost, or reductions in product
Case Studies 17 through 21, presented in Appendix D , provide
additional insight into the importance of determining process