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BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention relates generally to a computerized manufacturing
system and, in particular, to a new and novel method for controlling the
production, including pricing, costing, scheduling etc., by such a system.
(2) Description of the Prior Art
Material Requirements Planning (MRP) is the technique for determining the
net time phased requirement of dependent items parts or sub-assemblies
from known (e.g. sales orders) or assumed (e.g. sales forecast)
independent demand. A Bill of Materials (BOM) is used to define a
relationship between the independent demand items at one level and the
dependent demand items at the next lower level. In addition, the BOM also
is used as the basis for costing and pulling materials from inventory for
released work orders. Typically MRP planning is carried out by a general
purpose computer operating under software control.
In most prior art MRP systems, there is an "one-for-one" relationship
between an independent demand item produced and the BOM which defines the
dependent items and the quantity of each dependent item required to build
the independent demand item. Some MRP systems have the additional
capability of including limited conditions in the BOM. However, such MRP
systems do not include any general provision for providing a "many-to-one"
relationship between the independent demand items and the BOM.
Unfortunately such MRP systems pose a problem for an user which
manufactures and sells products that are available in a wide variety of
options. Upholstered furniture companies, for example, sell chairs by
style number. They are often available in a variety of fabrics and
finishes. Another example is found in the apparel industry where it is
common to specify product by style, size and color.
The general MRP solution for this type of manufacturer is to enter into its
MRP system a product number and a BOM for each possible style/option
combination. While this approach is conceivable, it would necessitate
thousands of unnecessary product numbers and BOMs. This would create a
huge problem in maintaining the BOMs and entering the data into the MRP
system. As a result, there now are a number of industry specific MRP
systems which allow, for example, a furniture manufacturer to enter
individual styles, fabrics and finishes which correspond to specific
sub-BOMs, thereby substantially reducing the total number of BOMs required
to be maintained and entered into the MRP system.
Certain disadvantages become apparent for such a MRP system. First, these
MRP systems are specific solutions rather than general purpose. Thus, they
can not be readily adapted for different industries or even different
manufacturers in the same industry. Furthermore, a manufacturer can not
add or easily modify his product structure. For example, adding the option
of a sectional sofa for an existing style (i.e. add another "degree of
freedom").
There have been some attempts at otherwise simplifying, limiting the data
entry into the MRP system, and increasing the reliability of production
estimates of the MRP system. For example, the Dye patent (U.S. Pat. No.
4,459,663) discloses a data processing system for automatically and
efficiently controlling the manufacture of designated end item products
and components which are used to make them. The MRP system is a basic MRP
system which, in addition, incorporates an unique feature whereby the
system automatically maps all end item stock to the jobs on a priority
basis every time a MRP report is produced. As a result, it is not
necessary to continually update the MRP system with changes made to the
original stock allocation as required in prior art approaches.
The Carlson et al reference (U.S. Pat. No. 4,646,238) discloses a MRP
system for controlling the flow of semiconductor products and their
components through a production facility. In addition to a conventional
MRP system, the Carlson patent also provides a method for by-product
planning, co-product planning, and downgrading. However, neither of these
references provides a solution to the problem of problem in maintaining
the BOMs and entering the data into the MRP system for a distributor or
manufacturer which sells products that are available in a wide variety of
options.
It has thus become desirable to develop a MRP system which allows, for
example, a furniture manufacturer to establish an one-to-one relationship
between a style number and its BOM without regard to selected fabrics or
finishes and, in addition, allows the manufacture to utilize user-defined
formulas which determine the quantity and/or size of an item based on the
selected options, thereby eliminating the extra number of BOMs required to
be maintained and entered into the MRP system.
SUMMARY OF THE INVENTION
The present invention is directed to an integrated MRP system for
distributors, manufactures and job shops. The MRP system of the present
invention includes multiple modules including inventory control, sales
order processing, purchasing, estimating and standards, work order
control, and MRP. These modules may be interfaced to an existing
accounting package which includes accounts receivables, accounts payable,
general ledger and payroll modules. The MRP system of the present
invention is specifically directed to an user which manufactures and sells
products that have a wide variety of options. In particular, the MRP
system of the present invention provides two key features. The first
feature allows the user to define items from which one to six options may
be specified to uniquely characterize the product for a customer order,
purchase order, or work order. The user is only required to maintain
limited information about each combination of item and options.
The second unique feature of the MRP system of the present invention is the
application of user-defined formulas similar to those that are used in
conventional spreadsheet programs. This is particularly useful in defining
the BOM since the MRP system of the present invention allows the user to
include user-defined formulas which determine the quantity and/or size of
a part based on the selected options. Thus, the MRP system of the present
invention allows the user who manufactures sells a number of styles with a
wide variety of options to employ an MRP system which does not require the
high maintenance overhead which is currently required by prior art MRP
systems.
Accordingly, one aspect of the present invention is to provide a computer
system for controlling the production, including pricing, costing,
scheduling etc., of manufactured items having means for receiving and
storing production information and means for interrogating the stored
production information and using the result of such interrogation to
create a parameter table containing selected production information and
utilizing calculations based on the information from the parameter table
to control the production of the manufactured items.
Another aspect of the present invention is to provide a computer system for
controlling the production, including pricing, costing, scheduling etc.,
of manufactured items having means for receiving and storing production
information and means for interrogating the stored production information
and using the result of such interrogation to create a parameter table
containing selected production information and utilizing calculations
based on the information from the parameter table to control the
production of the manufactured items, wherein the user may define formulas
for the calculations to be performed utilizing the parameter table.
Still another aspect of the present invention is to provide a computer
system for controlling the production, including pricing, costing,
scheduling etc., of manufactured items having means for receiving and
storing production information and means for interrogating the stored
production information and using the result of such interrogation to
create a parameter table containing selected production information and
utilizing calculations based on the information from the parameter table
to control the production of the manufactured items, wherein the system is
selectively operable between pre-determined and user-defined formulas for
the calculations to be performed utilizing the parameter table.
These and other aspects of the present invention will more clearly
understood after review of the following description of the preferred
embodiment of the invention when considered with the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a generalized block diagram of a programmable computer system
suitable for implementing the exemplary embodiment of the present
invention;
FIG. 2 is a generalized flow chart illustrating the relationship between
the program modules of the present invention;
FIG. 3 is a schematic diagram representing the data structure in a computer
system implementing the present invention;
FIG. 4 is a generalized flow chart illustrating the sequence of operations
performed by the machine for the sales order entry module;
FIG. 5 is a generalized flow chart illustrating the sequence of operations
performed by the machine for the inventory control module;
FIG. 6 is a generalized flow chart illustrating the sequence of operations
performed by the machine for the purchasing module;
FIG. 7 is a generalized flow chart illustrating the sequence of operations
performed by the machine for the estimating and standards module;
FIG. 8 is a generalized flow chart illustrating the sequence of operations
performed by the machine for the work order control module;
FIG. 9 is a generalized flow chart illustrating the sequence of operations
performed by the machine for the MRP module;
FIG. 10 is a detailed flow chart illustrating the process of Product
Standards Entry/Change shown in FIG. 7;
FIG. 11 is a detailed flow chart illustrating the process of Detail Formula
Entry/Change shown in FIG. 7;
FIG. 12A is a detailed flow chart illustrating the process of Estimate
Entry/Change shown in FIG. 7;
FIG. 12B is a continuation of the detailed flow chart shown in FIG. 12A
illustrating the function block for Copying the Product Standard Detail
Records;
FIG. 13A is a detailed flow chart illustrating the process of Estimate
Calculation shown in FIG. 7;
FIG. 13B is a continuation of the detailed flow chart shown in FIG. 13A
illustrating the process of Estimate Calculation shown in FIG. 7; and
FIG. 14 is a detailed flow chart illustrating the process of Formula
Processing shown in FIG. 7.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to the drawings in general and to FIG. 1 in particular, it
will be understood that the illustrations are for the purpose of
describing a preferred embodiment of the invention and are not intended to
limit the invention thereto.
FIG. 1 provides a block diagram of a typical computer system 10 programmed
in accordance with this invention. In the exemplary embodiment, the system
10 includes as "hardware" a Data General model MV/2500 computer and, as
"software", a commercially available operating system suitably programmed
to execute COBOL program instructions in accordance with this invention.
Typically, such a computer system 10 includes a processor unit 12 having
human interfaces via a CRT display 14 and a manually activated keyboard
16. A disk store 18 conventionally includes a data base of, for example,
inventoried fabric pieces and associated color, length, location, etc.
parameters which can be readily machine accessed by the processor 12 under
suitable program control. A RAM 20 is typically also included for program
storage. A suitable hard copy output device 21 can be used to generate a
permanent record. However, it should be understood that the spirit of the
invention can also be performed by hard-wired circuitry or a special
purpose computer. Such devices contain the same basic elements which are
utilized when instructed by a software program according to the present
invention. Consequently, the scope of the present invention is intended to
be determined according to the following claims and not by the particular
embodiment described herein.
Keeping this in mind, the present invention will be described in connection
with how a general purpose computer can be programmed and operated to
achieve the objectives of the present invention. From the following
detailed description one skilled in the art will be readily capable of
generating the specific instruction set for programming the computer to
perform the desired operations.
In the present invention, the stored program within RAM 20 will include a
program for generating the BOM in accordance with this invention. It will
be appreciated that the portions of such RAM which store program segments
directed toward accomplishment of a particular function will necessarily
constitute a portion of the provided apparatus of "means" for achieving
that same respective function in this exemplary embodiment.
In the preferred embodiment, the MRP system of the present invention
includes an unique means of processing the BOM which allows the user to
specify for each line of the BOM the type of calculation which is to be
performed either: 1) "default" which is defined as the parts quantity
times the production quantity or 2) a formula calculation which can be any
calculation based on the information in any of 150 fields stored in a
parameter table.
When the user sets up a BOM in the MRP system of the present invention, it
has the option of specifying for each detail of the BOM the following
information:
a) "Default" or "formula calculation" (if "formula", then the user
specifies the formula code to be executed).
b) The materials item code which can be changed by the formula.
c) The quantity of the item, per unit of output (this value can also be
changed by the formula).
In each of the modules in which BOM processing occurs, Estimating and
Standards, MRP, and Work Order Control, the MRP system of the present
invention performs the following:
a) Sets up the parameter table.
b) Default calculation or formula calculation as requested by the user.
c) Moves selected fields back to the appropriate record (i.e., cost detail,
MRP detail, or Work Order Detail) from the parameter table).
FIG. 2 illustrates the overall relationship between the modules which
comprise the MRP system of the present invention. The modules are Sales
Order Entry 22, Inventory Control 24, Purchasing 26, Estimating and
Standards 28, Work Order Control 30 and MRP 32 and are described briefly
below. The six modules are written in COBOL and, in the preferred
embodiment, interface with a General Ledger 34, Accounts Receivable 36,
Accounts Payable 38, and Payroll 40 system available from SouthWare
Innovations, Inc., Auburn, Ala.
1. Sales Order Entry Module
The Sales Order Entry Module 22 allows the user to enter sales orders, ship
stock against those orders, and produce invoices for shipped orders. It
also has the capability to produce after-the-fact invoices. During order
entry, credit checking is performed and a Sales Acknowledgement may be
printed. The Sales Order Entry Module 22 has the capability to assign
orders to truck loads based on user-defined load capacity calculations
(e.g., cubic feet, square feet, weight, etc) . Orders may be entered for
items which are shipped from stock, drop shipped by a vendor, or customer
manufactured items. They may be for items which are tracked by serial
number, lots, or items with options. The Sales Order Entry Module 22 also
includes customer invoicing. Invoices may be produced for items which have
been shipped or for jobs which were entered into the Work Order Control
Module. The Sales Order Entry Module 22 interfaces with the Inventory
Control 24, Purchasing 26, Work Order Control 30, MRP 32, Accounts
Receivable 36 and General Ledger 34 modules.
2. Inventory Control Module
The Inventory Control Module 24 allows the user to track finished goods
and/or raw material inventory. The Inventory Control Module 24 supports
multiple warehouse locations. Items in inventory may be divided into
categories which is useful in sales analysis. Furthermore, the user can
specify that items in a category may have up to six (6) different options.
Each of these options may have user-defined description and editing
characteristics. The Inventory Control Module 24 maintains an inventory
balance for each item or item/option combination. It relieves inventory
during invoicing and issuing materials to work orders. It handles purchase
orders, receipts, physical inventory counts, and adjustments. Items may be
tracked in inventory by serial number or lot number. The Inventory Control
Module 24 also includes three types of inventory commitment and reorder
techniques. Items may be committed to a sales order or a stock level,
custom, or net requirements basis.
3. Purchasing Module
The Purchasing Module 26 aids the user in issuing purchase orders as well
as monitoring receipts. The Purchasing Module 26 first produces a
recommended purchase list. It automatically prints the purchase order, if
desired, and monitors open purchase orders until they are received. The
cost of purchased items may be entered at a later date. The Purchasing
Module 26 interfaces with the Accounts Payable 38, Inventory Control 24,
Sales Order Entry 22, MRP 32 and Work Order Control 30 modules.
4. Estimating and Product Standards Module
The Estimating and Product Standards Module 28 allows the user to estimate
the cost of a "one time" job or to establish standards for products which
are manufactured on a repetitive basis. The Estimating and Product
Standards Module 28 defines the labor, material, outside services and
other direct costs used to build a product. This module also allows the
user to define standard operations which may be used across several
products or jobs but which have independent standards. The Estimating and
Product Standards Module 28 allows the user to define flexible, formula
based Product Standards. Both usage and direct costs may be values which
the user specifies as part of the Product Standards or they may be
calculated by user-defined formulas. The Estimating and Product Standards
Module 28 optionally calculates manufacturing and general and
administrative overhead costs. It may also be used to estimate a selling
price based on up to four (4) user-defined pricing methods formulas for
each of four different production quantities.
5. Work Order Control Module
The Work Order Control Module 30 allows the user to enter work orders into
the system and to track them until they are completed. An order may be
based on a Product Standards, an estimate, or may be a "one time" order.
The user also may select shop scheduling. This module supports either a
plant or department level calendar and allows the user to specify machine
and employee capacity by work center. Work orders may be scheduled using
either forward or backward scheduling. It produces a wide variety of
production documents and lists, including production pickets and a
material list. The Work Order Control Module 30 tracks work through the
plant. Actual labor and material usage may be reported, or it may be taken
as standard. The Work Order Control Module 30 tracks direct costs,
manufacturing overhead costs as well as general and administrative
overhead costs. It includes reports and inquiry screens which compare the
actual cost to the standard or estimated costs.
6. MRP Module
The MRP Module 32 allows the user to forecast material and capacity
requirements necessary to meet the Sales and Production Plan during each
of the periods in the planning horizon. It produces an Exception Report
which identifies resource shortages with respect to the current production
schedule. It also produces a planned Purchase Order list and Planned Work
Order List which represent the order requirements for the current plan.
The MRP Module 32 interfaces with the Work Order Control 30, Estimating
and Standards 28, Inventory Control 24, and Purchasing 26 modules. It may
also be adapted to interface with optional Sales Forecasting 42 and
Production Planning 44 modules.
As best seen in FIG. 3, a schematic diagram representing the data structure
in a computer system implementing the present invention is shown. The
primary files, discussed in more detail later, are each accessible by two
or more of the modules of the present invention. Each of the primary files
are accessible by the MRP Module 32 which integrates the contents of the
primary files and selected secondary files (not shown).
Turning now to FIG. 4, the details of the Sales Order Entry Module 22 are
illustrated. The primary file used by the Sale Order Entry Module 22 is
Sales Order File 42. In the preferred embodiment, the Sales Order Entry
Module 22 offers the user two alternatives for processing sales orders.
"One step" invoicing is the simplest and involves the direct entry or
orders for invoicing. The other alternative, "two-step" processing, allows
the user to enter orders, print acknowledgements, generate production
and/or shipping documents, then produce invoices. Both alternatives may be
used concurrently.
The user may produce a variety of different kinds of orders, including drop
shipments, transfer orders from one warehouse to another, credit memos and
billing adjustments. During sales order entry, the user may search for a
customer by the customer number, index lookup, or alphanumeric (customer
name) search. Additionally, the user may add a new customer during order
entry without having to exit the program and return to a menu.
The user also may assign multiple ship-to addresses to each customer. When
entering orders, the user may select the same ship-to as the billing
address, or enter the code for one of the alternate ship-to addresses for
the customer. The user also may use up to six user-defined options for
each item. Use of the valid option checking feature insures that an
acceptable value will be entered for each option at order entry. The Sales
Order Entry Module 22 checks stock availability during order entry. If
stock is not available, the user will have the option of shipping
available stock, creating a back order, cancelling the order line, or
entering a substitute item.
Shipping dates may be assigned by order header or by detail line, allowing
the user to use different shipping dates for each line on an order. The
user may use comments on documents produced by the system, including sales
orders, purchase orders, bills of lading, production documents, and
invoices. The user also may specify whether the comment is for internal
use, or the user may set up standard, or recurring comments to reduce data
entry.
The Sales Order Entry Module 22 includes an automatic credit checking
feature which allows the user to assign a credit limit and credit
expiration date for each customer. During order entry, the Sales Entry
Order Module 22 checks credit availability for the customer and places a
credit hold on the order if sufficient credit is not available. The user
may take advantage of the Truck Load processing feature if the user
deliver orders on company trucks, ship in complete truck loads, or need to
group orders together for processing.
The Sales Order Entry Module 22 offers an easy to use order inquiry program
which is designed for use by customer service representatives who take
telephone inquiries from customers. The inquiry offers several alternative
ways to locate an order and shows up to date information at several levels
of detail.
An UPS processing feature automatically calculates UPS charges, adds them
to the order, and prints the UPS manifest. It can handle air shipments as
well as COD and other special charges. Packing tickets may be generated by
bin location to facilitate selection of stock for shipment.
Sales commission calculations may be either default or formula based
calculations based on commission rates for each customer, order shipping
address, order or item. In addition, the system handles multi-salesman
commission splitting for up to a four way split.
The Sales Order Entry Module 22 allows the user to set up a cross reference
table for entering orders using the manufacturing operation customer's
items numbers, categories, and descriptions. The customer-defined
information will be printed on documents produced for the customer, while
the standard item number and description are printed on documents for
internal use. This cross reference table also allows the user to establish
special pricing for this customer.
The Sales Order Entry Module 22 allows for the use of royalty calculations
with user-defined formulas. Item pricing and/or discounting may be handled
using formulas, tables, or item pricing. The customer type determines how
pricing will be applied for each customer, allowing the user to use
different methods for different customers.
Turning now to FIG. 5, the Inventory Control Module 24 is shown. The
Inventory Control Module 24 allows the user to maintain inventory records
for multiple warehouses or locations. If the same item is found in more
than one location, the system maintains information separately for each
physical location. The Inventory Control Module 24 allows the user to
maintain records concurrently for a variety of different items types,
including:
a) Serial Items--items for which it is necessary to maintain a serial
number identification for each occurrence in inventory.
b) Lot or Bin--Items which require identification by lot grouping or bin
placement within a physical location.
c) Option--Items which have assigned options such as color or size. The MRP
system of the present invention has the ability to maintain up to six
different options for each category of items.
d) Regular--Items for which none of the above conditions apply.
The Inventory Control Module 24 has several features to facilitate the
processing of a physical inventory. For recording physical counts, the
Inventory Control Module 24 prints work sheets by location and in a
variety of sequences. To ease entry of counted figures, the Inventory
Control Module 24 prompts the operator for each entry in the same sequence
that the work sheet was printed. Before updating the inventory quantities,
the Inventory Control Module 24 operates a comparison printout of the old
and new figures. Discrepancies may be checked and corrected before
updating the physical count results.
Inventory adjustments are made by the Inventory Control Module 24 in a
three-step process which insures an audit trail of all entries. The first
step is the entry of inventory adjustments. The second step is the
printing of an edit list or entry register. After verification, and
corrections if necessary, the adjustments are posted, completing the
process. The Inventory Control Module 24 has inquiry capability tailored
to the item, and providing up to date information at several levels of
detail.
The Inventory Item File 44 utilized by the Inventory Control Module 24
includes raw materials as well as finished products, eliminating the need
to maintain separate files. The Inventory Item File 44 contains three
different costs for each item: standard cost, last cost and average cost.
The last cost and average cost values are automatically updated by the
Inventory Control Module 24 each time the item is received into inventory.
Inventory costing may be based on any of these three costs.
The Inventory Control Module 24 allows Item pricing based on one of five
different price levels maintained in the item file. The system offers
several calculation programs to automatically recalculate item pricing.
Information about item acquisition is maintained through the Item Source
file. There are several different source types, including Vendor for
purchased items, Plant for manufactured items, and Locations for items
received through an inventory transfer. Multiple sources and source types
may be maintained for each inventory item.
As best seen in FIG. 6, the Purchasing Module 26 aids the user in issuing
purchase orders as well as monitoring receipts. The primary file used by
the Purchasing Module 26 is the Purchase Order File 46. The Purchasing
Module 26 first produces a recommended purchase list. It automatically
prints the purchase order, if desired, and monitors open purchase orders
until they are received. The cost of purchased items may be entered at a
later date. The Purchasing Module 26 interfaces with the Accounts Payable
38, Inventory Control 24, Sales Order Entry 22, MRP 32 and Work Order
Control 30 modules.
Turning now to FIG. 7, the Estimating and Product Standards Module 28 is
illustrated. The primary file used by the Estimating and Product Standards
Module 28 is the Product Standards File 48. This file is similar to a
traditional BOM, in that it specifies the exact components of production
required to make a product. These components of production may include
Materials, Labor, Outside services, and up to seven user-defined Other
costs. However unlike the prior art, the Estimating and Product Standards
Module 28 also has the ability to use either default methods or formulas
for calculating Quantities, Costs, Lead Times, and Overhead. Formulas may
be entirely user-defined and may consider any of up to 150 variables from
the files used by the Estimating and Product Standards Module 28.
The Product Standards records used for MRP planning also may easily be
copied into either estimates or work orders. From an estimate, costing,
pricing, and inventory requirements are calculated. From a work order,
inventory is reduced, production documents are generated, and actual costs
are charged as they are incurred. Overhead costs may be considered in
estimate calculation using any of a variety of user-defined alternatives,
including formulas. The user also may maintain estimates for regular
production items as well as special or custom items, and multiple
estimates may be maintained for each item.
Another important file maintained through the Estimating and Product
Standards Module 28 is the Standard Operations File 50. The Standard
Operations File 50 includes procedures, labor operations, miscellaneous
cost items, or comments which are recurring and may be required for
multiple products or items that the user want to build. Each Standard
Operations item may be used several times in building a product, and/or it
may be used in building many different products. The Standard Operations
File 50 allows the user to make changes to the Standard Operations record
to update all the different Product Standards which use the operation.
The Estimating and Product Standards Module 28 allows estimates to be
easily changed, calculated, or copied. This gives the user the ability to
easily examine the impact of changes in the various components of
production required to make a product. Each estimate may include pricing
for up to four different manufacturing quantities, allowing the user to
examine the efficiencies achieved with different volumes.
As best seen in FIG. 8, the Work Order Control Module 30 is illustrated.
The primary file used by the Work Order Control Module 30 is the Work
Order File 54.
Work orders are generated as part of a three-step process in which they are
entered, edited and posted. Each Work Order record consists of a header
and one or more detail lines. The Work Order detail lines are identical in
structure to the Product Standards detail records. When creating work
orders, the user has the option of duplicating the Product Standards
records as Work Order detail lines. Changes can then be made to the Work
Order detail lines without affecting the Product Standards record.
The Work Order Control Module 30 allows the user to establish default
overhead and labor rates by plant, department, or work center. The setting
of the manufacturing operation control record determines in which of these
files the default rates will be established, insuring the user the most
meaningful default values. The default rates may be overridden for
specific work orders during work order processing.
The Work Order Control Module 30 also allows the creation of a customized
calendar which is used for production scheduling. The manufacturing
operation control record determines whether the calendar is to be
established by plant or by department. The calendar specifies standards
work days and hours, as well as exceptions such as holidays. The Work
Order Control Module 30 allows the use of up to 9 reporting stations
within each plant. Reporting stations are sequential checkpoints at which
manufacturing progress is reported to the system.
Quantities of labor, materials, and other items used in the manufacturing
process may be reported to the MRP system of the present invention at
actual or standard usage. If reporting is to be done at actual, then the
quantities must be monitored and entered. If reporting is to be done at
standard, then the standard quantity will always be used for relieving
inventory and calculating costs. Each work order may have some items which
are reported at standard and some reported at actual, or all items on a
work order may be reported at either standard or actual.
For each Work Order detail line, the Work Order Control Module 30 maintains
both estimated and actual quantities and costs. Estimated amounts are
calculated from the Work Order detail lines when the work order is posted,
and these figures are used for committing inventory and scheduling. Actual
amounts are calculated after reporting occurs for the Work Order detail
line regardless of whether reporting is done at actual or standard. The
Work Order Control Module 30 maintains both figures for comparison.
The Work Order Control Module 30 has the capability of generating work
orders from sales orders using the Auto Entry option. In addition to
reducing the amount of data entry required to generate a work order, this
links the work order record with the sales order for which it was
generated.
All quantity and cost calculations performed by the Work Order Control
Module 30 may be based on the default or the formula method. In most
situations, the default method is adequate, but the formula method
provides a very powerful tool in complex situations where many factors
must be considered.
The Work Order Control Module 30 tracks and places into inventory,
defective items which are generated as part of the manufacturing process.
Work Order inquiries show Work Order header and detail information,
including status, estimated costs, and estimated quantities in a similar
manner as shown in Table 2. Work Order inquiry also displays up to date
actual costs and quantities which have been posted.
As discussed above, the MRP Module 32 allows the user to forecast material
and capacity requirements necessary to meet the Sales and Production Plan
during each of the periods in the planning horizon. It produces an
Exception Report which identifies resource shortages with respect to the
current production schedule. It also produces a planned Purchase Order
list and Planned Work Order List which represent the order requirements
for the current plan.
MRP planning may be performed in either of two modes: net change or
regenerative. Net change is the process of determining the change in
material and capacity requirements which results from changes in demand,
supply, and on hand balances which have occurred since the last time the
MRP system was updated.
In regenerative MRP planning the MRP detail files are first deleted and
then rebuilt from existing sales orders, purchase orders and work orders.
The MRP records contain the quantity of demand for each sales order and
work order detail record or the quantity of supply for each purchase order
or work order header record. The MRP records are stored by Inventory Item
number in date and time due sequence. Each Inventory Item record which
contains either supply or demand is automatically flagged for MRP
planning.
As best seen in FIG. 9, the regenerative MRP planning operation is
illustrated. The MRPA, MRPB, MRPC, and MRPD blocks perform the copying
functions, as discussed above, to rebuild the MRP records. Then the MRPE
block performs the time phased netting operation. Each record in the
Inventory Item File 44 is processed until a complete pass is made through
the Inventory Item File 44 without detecting a flagged item. Each flagged
record in the Inventory Item File 44 is processed with its corresponding
MRP record in date and time sequence. For each MRP record a new balance is
first calculated. If the value of the new balance is less than the value
of an user-defined safety margin value for that particular item, then a
new record is written to the Requirements File that indicates that a
purchase order for purchased items or a work order for manufactured items
is to be issued or changed.
When a work order is to be issued or changed, the MRPF block explodes the
requirement for the item, according to the definition in the Product
Standards File 48, and writes it to the MRP detail file. The same default
or user-defined calculations as used by the Estimating and Product
Standards Module 28 and the Work Order Control Module 30. As additional
requirements for items are written into the MRP detail file, the
corresponding Inventory Item record is flagged.
As can be understood from the above discussion, the MRP system of the
present invention allows the user to control the calculations utilized by
the system. Thus, the user may select either default or user-defined
formula calculations for each of the following:
(1) Customer Pricing;
(2) Customer Discounts;
(3) Truck Capacities;
(4) Salesmen Commissions;
(5) Designer Royalties; and
(6) Product Standards/Estimate/Work Order/MRP detail quantity and cost
calculations.
The formulas operate on the "universe" of information which is stored in a
parameter table which is unique for each of the above. For example, the
parameter table for Customer Pricing contains Customer Type, Customer Sold
To, Customer Ship To, and Salesman information. However it does not
contain information about components of production. On the other hand, the
parameter table for calculating Estimate details does not contain Customer
information. For each of the above, both the default and formula
calculations are performed utilizing the information in its associated
parameter table.
The instruction set for the user-defined formulas for each of the above are
identical. The instructions are stack-oriented and utilize "reverse
Polish" notation. The formula instruction set allows a degree of user
programming and includes "If", "Then", "Else", and "Perform" operations.
For the purpose of illustrating its operation, the use of formulas in the
Estimating and Product Standards Module 28 will be discussed in more
detail, however, t | | |
