Production Scheduling

 

1.    Principles

The basic objective of scheduling production is to maximise and optimise the use of production resources available on assembly line or in a manufacturing plant.

These resources typically include:

  • Machine Resources
  • Human Resources
  • Material availability
  • Tooling

Optimising scheduling, together with optimising manufacturing/assembly processes, can have a major impact on production time and, therefore, production costs.

The aim of production scheduling is to maximise the efficiency of the production/assembly plant and to reduce costs.

2.    The Problem

The output of each process is the input for the next process and this often leads to conflicts in output demand.  The primary issue here is that each process or production line wants to maximise its own efficiency, resulting in less set-up and tolling time which means less overhead for each production run.  A typical example of this is the requirements of each plant in the production of motor vehicles.

  • The body assembly plant will want to assemble a run of a particular type of body – e.g. a four-door hatch-back. This results in tooling up and programing the robotics once, producing a run of this type of body, and then tolling up etc. for the next type of body.
  • The paint-shop will, for the same reason, want to do a run of one paint colour at a time.
  • The Assembly line will have a sequence of loading each vehicle onto the trim line. Based on the trim line sequence, a call-off will have been sent out to sub-assembly (e.g. Dashboard) suppliers – many of which are Just-in-time suppliers.

Although I have used a motor vehicle assembly plant as an example, the same principle applies to many other industries, for example the Paper and Printing industry or the Clothing industry.

3.    The Cause

The causes of these “conflicts” are mainly due to:

  • Set-up and tooling costs, where the production line wants to minimise the amount of time spent on preparing for a production run or Work Order.
  • Resource availability, where either the number of machines or the availability of skilled operators is a restraint.
  • Resource capacity, where the machines are capable of producing a finite number of items in a given time frame, or the available manpower (e.g. Stockroom) is a restraint.
  • Machine down-time, where a machine is either scheduled for maintenance or has broken down.

4.    The Solution

The solution to the above is an effective and visual planning tool which takes cognisance of the various inputs and assists the production planner in the scheduling of work orders.  These inputs include:

  • Manpower requirements and availability
  • Machine requirements, capacity and availability
  • Tool requirements and availability
  • Material availability
  • Production demand:
    • Date required
    • Order priority

Sage X3 Version 11 has the following functionality which addresses these requirements.

  • Factory calendars and shift/s
  • Bills of materials, defining the versions of the products / BOMs applicable to the finished or semi-finished products
  • Work Centres, which define:
    • Type of resource (Manpower, Machine)
    • Number of resources
    • The type of scheduling for the resource; e.g. a pool of machines can be run in parallel or can be alternates if a machine is at capacity
    • The capacity of the machine
    • Tooling
  • Routings, which define the operations required, the associated work centre/s, manpower and materials linked (assists with JIT supply of production process spans several days/weeks)
  • Work Orders, defining the WO specific production information such as requirement date, priority.
  • Materials Requirement Planning which assists the procurement and warehousing staff with ensuring material availability
  • A Graphical Production Scheduler, showing the complete production schedule, displayable from many different views:
    • Work orders, Customer Orders, Products
    • Work Centre loads
    • Factory overview
    • Customisable
  • The production scheduler allows for system scheduling, manual rescheduling
  • Publishing of the scheduling changes, which updates the Work Orders with new scheduling information. Off-line changes are considered by MRP.