SECTION XI. ORDERING CASTINGS
The process of ordering a casting should define and support the cooperative
working relationship between customer and foundry leading to the development and
production of castings which provide complete satisfaction to the end user and profit to
both the customer and foundry.
The Ordering Process
Formalizing Quality Management
To survive and prosper in the face of intense international competition, manufacturers
are adopting an innovative approach to product development that affects not only their own
companies but also their casting suppliers. This new approach uses the concept of
multifunctional, interactive team design to improve overall product quality and
performance, reduce manufacturing costs, and shorten product development time. This
concept also imposes a new role on foundries who are coopted as partners into an extended,
vertically integrated manufacturing system. In their new role as preferred suppliers,
foundries must have the capability to not only supply quality assured products on time and
at competitive cost, but also provide services that assist in the design, manufacturing
and marketing of their customers' products.
In order to define and support the
working partnership between customer and foundry, ordering castings has been
changed from a simple commercial transaction to a multi-stage process that
begins with the preliminary design of the casting and ends with qualification of
the foundry for the production of commercial castings (Table
11.1 Stages Involved in Ordering Castings.
3. Final Design
Quality Management System
5. Order Castings
The objective of this stage is to establish a sufficiently clear definition of
the general performance requirements of the casting to permit a selection of
candidate materials and production methods and to begin the definition of
supplier performance standards. However, supplier selection should begin at the
earliest possible point in the design process to take advantage of the expertise
of the foundry partners.
Selecting the right foundry partner can
be the most important part of the purchasing process. Many of the selection
criteria depend on the customer's particular casting needs, but some of the most
important criteria are assuming universal, and non-negotiable, status. The most
important customer-specific criterion is the need for a good "fit"
between the customer's requirements and the foundry's strengths. The need for
"fit" is becoming more important as foundries become increasingly
specialized in order to become the preferred supplier in targeted "niche
markets". Categories in which fit is important are casting properties,
production characteristics and foundry capability. Significant casting variables
include size, complexity, dimensional accuracy, surface finish, composition and
properties. Casting volume is one the more significant production variables.
Critical foundry capabilities that can vary significantly according to market
specialization include quality and cost control, production flexibility,
expertise and customer service.
Conformance to quality and
delivery requirements and competitive pricing are becoming universal and
necessary criteria for supplier selection. Of these, the ability to meet quality
requirements, and a commitment to continuous quality improvement are the most
fundamental characteristics of a preferred supplier. These characteristics can
be identified and evaluated with a supplier audit which follows the checklist
shown in Table 11.2. The achievement of conforming
and continuously improving quality enables the foundry to meet both quality and
delivery requirements, offer competitive prices and provide other
quality-related benefits such as increased manufacturability and component
Table 11. 2 A
checklist for evaluating the commitment of potential foundry partners to quality
conformance and improvement.
|1. Does the foundry have a written
policy stating its quality objectives?
2. Do the foundry's quality objectives include a strong commitment to
quality and the continual improvement of quality?
3. Does the foundry have an operating quality system that commits
and enables all foundry employees to meet the foundry's quality
4. Can the foundry demonstrate that its processes have the capability
of producing castings consistently within specification?
5. Does the foundry use quality achievement tools such as FMEA and SPC
to continually improve its process capabilities?
6. Does the foundry have an internal quality audit and evaluation
system to ensure that all quality procedures are being followed?
7. Does the foundry have manuals defining all standard operating
practices and quality procedures?
8. Does the foundry have a policy for periodically evaluating and
updating all manuals to reflect current practices?
should be a significant but subordinate criterion for supplier selection.
Awarding business to the lowest bidder, or using multiple suppliers to keep
casting prices low is rarely a successful strategy to reduce production costs
and increase component value. When price is given undue importance in the
purchasing decision, the successful bidder often sacrifices casting quality and
consistency. Similarly, when the multiple supplier strategy is used,
inter-supplier variations reduce casting consistency. Thus, regardless of the
method used, awarding business on purchase price alone will eventually lead to
reduced casting consistency and process capability, increased production and
nonconformance costs and decreased component quality. Although simplistic, the
product value equations in Table 11.3 serve as a
warning that minimizing casting purchase price may result in increased costs,
decreased quality and decreased value of the finished product. As the value
added to the casting by the customer increases, casting price becomes less
important and the negative consequences of low casting quality become more
11.3 The product value equation.
||= PURCHASE PRICE
TOTAL MANUFACTURING COST
|= PURCHASE PRICE
||+ PRODUCTION COST
||+ COST OF
|= PURCHASE PRICE
||+ PRODUCTION COST
||+ COST OF SERVICE
+ COST OF LSOT PRODUCTIVITY
+ COST OF SHIPPING REJECTS
+ COST OF PROCESS ADJUSTMENT
+ COST OF SCRAP & REWORK
+ COST OF ADMINISTRATION
+ COST OF DISTRACTION
+ COST OF REPUTATION
Final design is an iterative process involving close cooperation and liaison
between the customer's design team and the foundry. As shown in Figure
11.1, the casting under development is cycled through successive
design-feedback loops using first prototypes and then production samples until
successful commercial castings are produced. After each successful design
modification, operating plans are modified and appropriate conformance limits
established. Although acting only as an advisor to the customer's design team,
the foundry can play a critical role in optimizing casting performance and
minimizing casting costs.
Final design activities should
also include the cooperative efforts of both customer and foundry to reduce
casting and manufacturing costs while maintaining or increasing product quality.
Casting costs may be reduced by increasing overall process yield, reducing
molding and coremaking costs, reducing casting cleaning costs and eliminating
over-specification of the casting dimensions, composition and properties.
Manufacturing cost may be reduced by increasing foundry process capabilities in
dimensional and hardness control to reduce machining costs and redesigning the
casting to simplify manufacturing procedures and increase productivity.
This final step in the ordering process ensures
that both the customer and foundry have clarified and defined all casting
properties that are critical to manufacturability and product quality and have
agreed upon appropriate quality assurance methodology. In this important area of
specifying critical casting properties the foundry can play a very constructive
role in pointing out the sensitivity of the mechanical properties to casting
section size (Figure 11.2). This sensitivity
to section size can be reduced significantly by employing high purity change
materials, correct metal composition and special inoculation techniques.
Back to Top
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E. J. Broeker, "Build a Better
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7th Edition, QIT-Fer et Titane Inc, 1990, S. I. Kersey, Ductile Iron II,
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The Iron Castings Handbook,
Iron Castings Society, Inc., 1981.
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