Control system supplier Rockwell Automation is currently bringing to market a software system called Paint Shop Model Predictive Control (MPC), which is designed to predict and therefore accurately schedule and operate paintshop equipment in a way that can minimise their energy consumption

Todd Montpas, automotive and tyre market development manager for Rockwell in the US, explains that inaccurate scheduling is a major source of inefficient energy usage in automotive paintshops. He says that paintshops still fail to deal appropriately with interruptions to their operations, some of which are entirely predictable. He cites transfers between shifts and changes in vehicle types coming down the line as the most obvious examples.

Montpas says that a more accurate and reliable understanding of what might happen could help to save a considerable portion of the energy currently consumed. At the core of the matter is the fact that paintshops now ramp up their state-of-readiness sooner than they need to, for instance by firing up ovens to create and maintain required internal levels of heat and humidity in order to deal with any eventuality, inevitably using up both energy and money. Increasing product variability and decreasing batch size has also required paintshops to be repeatedly reset to cope with vehicles of different sizes and formats. Altering settings for humidity and temperature to cope with that variability involves “wait periods” which waste energy.

In short, Montpas characterises automotive paintshops as environments which are marked by unnecessarily long periods of high, unproductive energy consumption interspersed by episodes in which parameters are altered in an approximate and therefore inefficient manner.

Paint Shop Model Predictive Control

The recently released MPC product from Rockwell is intended to provide a solution to this problem. Montpas says that the software is not new but an adaptation of a system called Pavilion 8 which has been around for a decade or so. However, he emphasises that it is certainly “a new application in paint”, and though it has yet to build up any significant track record of usage in the industry, he is confident that the claims made for what it can deliver are “empirically-based”.

Those claims look impressive. According to Montpas they include:

  • Paint booth energy consumption reduced by 1-5%
  • Paint booth variability reduced by 30-60%
  • More consistent operation with consequent reductions in rework and stop-and-go repairs
  • Extension of intervals between booth cleanings

A core enabling factor of the new product’s capabilities is that is fed with accurate, timely data which is drawn directly either from sensors in the installation or the databases of related software systems. This means that the information it generates in turn enables the installation’s own control system to alter key parameters according to real requirements.

According to Montpas, implementation of the system does not require any change in the way that a paintshop operates - but he does suggest that a lot of existing installations may lack sufficient instrumentation to gather all the data it requires. In some cases, more sensors may be required.