| SFSA: Buyer - Purchasing Steel Castings |
The responsibility for buying steel castings lies primarily with the
purchasing department. However, contributions toward the evaluation,
selection, and monitoring of vendors are being made more frequently by
various departments. These may include product design, manufacturing,
quality control, inspection, and general management. This trend towards
broad input clearly indicates the need for a defined purchasing policy
that defines the responsibilities of the people involved and the extent
of their authority. The objectives of the steel casting buyer still
remain:
These goals can be readily attained when all parts of an effective
purchasing program are put into action.
Each steel casting is specifically designed and manufactured to perform a
given function under predetermined operating conditions. Due to the
varied requirements of each user, the steel casting industry has staffed
itself with qualified personnel to provide the user with expertise in the
selection of the specifications, casting design, foundry techniques, and
finishing processes.
The purpose of requesting a quotation for a steel casting is basically to
determine the lowest purchased casting cost. The buyer then must weigh
all of the provisions of the quotation including exceptions taken to
drawings, specifications, and processing requirements, as well as vendor
experience, tooling requirements, tolerances, finish allowances, and
delivery. Such factors as reduced machine work, better tolerances, and
reliability are particularly important to determine the lowest end cost
of the casting.
To avoid misunderstandings, reduce costs, and expedite the processing of
quotations the following information should be included in a request for
a quotation:
Every service a steel casting buyer may need is available in the steel
foundry marketplace. The question then becomes " where and who? "
The Steel Founders' Society of America publishes a directory of its members
and a detailed listing of all steel foundries in the United States,
Canada, and Mexico providing the buyer with pertinent information
relative to plant personnel, capacities, special services, types of
steel produced, and relative size of castings. With the Directory as a
starting point, an initial list of potentially acceptable suppliers can
be established. The refinement of this list may require collaboration
between the buyer's engineering, manufacturing, and quality control
departments depending upon the scope of the company's purchasing policy.
The listing of SFSA member companies from
Directory of SFSA Member Steel Foundries
is available on line.
Industry approved specifications as discussed in
Specifying Steel Castings,
provide the casting buyer with the tools necessary to establish
criteria for almost any casting application. These specifications do
not preclude special requirements that the buyer's technical staff
members may require. Variations from standard specifications can result
in misunderstandings, higher costs and disqualification of potential
vendors. If exception is taken to a provision in the main body of a
specification requirement (as opposed to taking exception to a
supplemental requirement of a specification), the resulting casting
cannot be held to compliance with that specification.
Pattern equipment design and the resultant costs can constitute a major
source of misunderstanding between buyer and vendor. The need to
construct new pattern equipment when existing equipment is available, a
requirement for a full split core box in place of a half core box, pattern
material, and mounted or loose patterns are but a few of the many areas of
discussion that effect the cost of the equipment. Invariably, the lowest
casting cost and highest casting quality evolve from the more
sophisticated pattern equipment, which generates the highest pattern cost.
Order placement is the most important phase in the buyer-seller
relationship, not only because it is the first pure contractual agreement
between buyer and seller, but also because it requires acknowledgment of
schedules and specific commitments.
For purchase commitments to be fulfilled according to schedule, all
relative information previously developed in the preliminary phases must
be detailed in the purchase contract. The basic elements of the contract
that should be clearly defined are:
If sample casting are required, the following additional requirements
should be provided:
If patterns are to be constructed by the supplier, the following
additional information should be provided:
If the patterns are to be supplied by the buyer, the following additional
information should be provided:
If the castings are to be supplied to special process specifications,
any of the following additional requirements can be requested:
It is extremely important that initial casting orders be complete and
accurate and that verbal orders be avoided due to their propensity for
generating errors through omission.
To get the best value from a steel casting requires a cooperative effort
by both the buyer and the seller from the early stages of the design
through the manufacturing process. Good planning ahead of time will pay
dividends for both you and your supplier.
Purchasing Policy
acceptable costs,
quality,
reliability,
and delivery,
Quotation Procedure
Beyond these basics, there are levels of buyer requirements that could
include vendor liabilities, which affect the casting cost drastically.
These could include receiving inspection acceptance and back charge
policy, casting return policy, expediting procedures, and sophisticated
controls not normally associated with the standard inquiry. A complete
understanding of these areas is best developed by an open relationship
between the buyer and the foundry representative, and the professional
attitudes and experiences that both can provide during the quotation
evaluation phase.
Material and inspection requirements.
Acceptable casting weight.
Drawing.
Pattern.
Delivery.
Selection of Casting Supplier
Specifications
Patterns
Order Placement
Purchase order number and date
Pattern number and /or part number
Pattern and machine drawing numbers with current revision notation
Quantity required
Material specification
Casting price
Delivery requirements
Shipping instructions
Number of samples required
Non-destructive examination requirements
Dimensional examination requirements, if any
In-process inspection, if required
Final machining approval, if required
Special tests, if required
Pattern price
Description of pattern to be supplied
Pattern delivery
Pattern mounting and rigging price
Description of pattern services
Pattern accuracy liability
Pattern delivery
Chemistry certification
Mechanical test certification
Brinell hardness ranges and test location
Impact test, type and results required
Ultrasonic examination including coverage requirements, specification
and quality levels
Magnetic particle or dye penetrate testing, include coverage
requirements, specification, and quality level
Radiographic examination including coverage requirements, approved
shooting sketch, specification, and quality level(s)
Special surface requirements
Special packaging
Preferences regarding the method of shipping.
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Last Modified: May, 2001 Copyright 1995 - 2004 by Steel Founders' Society Of America. All rights reserved. Address Comments to: blairr@sfsa.org |