Abstract
Global competition and changing customer requirements are putting major challenges in the production planning and control systems of manufacturing enterprises. Production planning and control requires robust methods able to cope with demand variability, processing times variability, routing sequences, resource availability, etc., between other sources of variation. Production planning and control significantly influences target performance criteria such as the delivery time, on-time delivery, work-in-process inventory, and resources utilization. Therefore, production planning and control is strategically important for the economic success of these enterprises and innovative production planning and control methods are required. This chapter describes how workload control, a leading production planning and control system for small- and medium-sized enterprises, operates and illustrates how it aids in shortening and stabilising throughput times based on a simulation study of a small made-to-order production system.
Top2. Literature Review
Simulation has been the predominant research method in the WLC literature until now. A number of implementation issues, towards the alignment between WLC theory and practice, have been discussed. Hendry, Land, Stevenson & Gaalman (2008) produced a comprehensive list of issues, categorised into the following categories: customer/market related; production process issues; WLC system issues; organisational embedding issues; and information flow issues.
This section makes a concise review of simulation studies in WLC literature relating performance to aspects of the production process to be controlled. This includes aspects such as, shop floor routings, sequence-dependent set-up times, assembly requirements and bottlenecks issues.
Key Terms in this Chapter
Throughput Time: The time required for a job (material, component, or subassembly) to pass through the manufacturing process.
Little’s Law: The relationship between the average time in system (W), the average arrival rate (?), and the average number in system (L) in steady state a queuing system is given by L= W?.
Backwards Scheduling: A scheduling method that plans backwards from the due date (or time) to determine the start date (or time).
Bottleneck: Any resource that has capacity less than the demand placed on it.
Simulation: Methods and applications to imitate or mimic real systems, usually via computer.
Utilization: The percent of the possible work time that a resource is busy.
Capacity: The maximum rate of output for a process, measured in units of output per unit of time.
Make-to-Order: A production strategy that produces products in response to a customer order without keeping any finished goods inventory.
Lead Time: A time parameter related to the time to produce something used for planning and control purpose.
Pre-Shop Pool: A “suspence file”, being nothing more than a notation in a scheduling book which takes the form of a pool of jobs.