The emergence and maturation of
process-specific MRP II systems over the past decade has
encouraged many process companies to implement MRP II as the
centerpiece of their corporate CIM and ERP programs. For
continuous flow manufacturers, a new MRP II system has a very
specific role to play within a family of other existing systems
which include:
• Computerized Process Control: Continuous
flow manufacturers have developed tremendous expertise in
process control technology, and have installed a vast array of
systems intended for real-time monitoring of plant activities.
These include Supervisory Control and Data Acquisition (SCADA),
Distributed Control Systems (DCS), Programmable Logic
Controllers (PLC), Statistical Process Control (SPC), and
expert systems. In order to keep the process conforming to tight
specifications, adjustments are made continually based on
readouts from analog and digital process controllers. In some
cases, sophisticated Proportional Integral Derivative (PID)
control loop tuning is used to keep temperatures and pressures
within tolerance.
One of the points of confusion among software
vendors as well as process manufacturers has to do with the
proper role of MRP II in the process control arena.
Specifically, what role do MRP II shop floor control (process
operations control, execution) modules play in a continuous flow
plant? The answer is, none! In continuous flow manufacturing,
MRP II is strictly used to plan, to control inventory, to
generate purchase requirements, and to cost. It is the function
of installed process control systems to execute production. Work
order-based MRP II shop floor control modules are a big turnoff
to this industry, and understandably so.
In order for MRP II to function at a higher
level, integration to process control is required to download
formulas and recipes to support production, and to upload
production counts and QC test results to support planning and
management decision-making.
• Corporate Legacy Systems: Today's
continuous flow manufacturer is likely to be one of many
plants within a division of a multinational coiporation. Plant
ownership has probably changed hands over the years. Entrenched
corporate systems on mainframes perform centralized functions
like order entry, general ledger, receivables and payables,
formulation, production planning, and some purchasing. Plant
systems handle scheduling, shipping, receiving, inventory
control, and quality control. For a new MRP II system to be
effective at the plant, it must generate the necessary financial
entries and reports to satisfy the corporate number crunchers,
and yet give the plant operating autonomy to run local
operations as they see fit.
For a new MRP II system to be effective at a
corporate level, legacy systems must gradually be replaced. This
process frequently involves downsizing from a mainframe to a
series of midrange computers. From a functional point of view,
MRP II must still accommodate the global corporate reporting
hierarchy in a way that is not constraining, but empowering.
This typically requires that the new system provide the
following capabilities:
— Multiplant planning and forecasting
— Multicompany financial reporting
— Centralized or decentralized financials, planning,
purchasing, formulation, and inventory control
— Multicurrency processing of orders, invoices, and
payments.
— Multiwarehouse inventory control
• Plant Operating Systems: Other systems
commonly found in continuous flow manufacturing plants include
Preventive Maintenance (PM), Laboratory Information Management
Systems (LIMS), logistics systems which support receiving and
shipping activities, and document management systems. MRP II
systems will not replace these, but will receive data from them
and pass data to them. As the number of these supporting systems
at the plants and at corporate grows, the MRP II implementation
project begins to take on the characteristics of a systems
integration project rather than just a straight-forward MRP II
implementation.
• Regulatory Systems: Continuous flow
process manufacturers are regulated by many government agencies
for a variety of reasons. Systems are in place to ensure
compliance to laws governing pollution controls, the handling
and disposal of waste products, the use of hazardous materials,
and the training and certification of employees. MRP II systems
are frequently integrated with these systems to support report
generation and to provide production history and transaction
audit trails.
