The Pros and Cons of Constant Production
At first blush, the term 'constant production' creates positive feelings. It makes us think of full order portfolios, successful products and high customer acceptance and demand. By constant production, we mean running our manufacturing operations at full load and aiming to maximize the percentage of time occupied by value added activities. In reality, running operations in this fashion can have both benefits and difficulties. Let's look at the positives first.
Fewer Startups and Shutdowns
Startups and shutdowns are notorious in the manufacturing industry as large time wasters. By smoothing out productive activities, we eliminate a lot of inactivity, especially for machinery that requires to reach certain operational conditions (for example temperature or pressure) before any productive action can start. Even if activities are not 24/7, the minimization of start/stop activities simplifies planning and now leaves us with how to deal with setups and maintenance.
High Plant Utilization Means Shorter Capital Investment Payback Period
There are various parameters for utilization. Some are time and productivity based, some are more oriented towards financial results. In any case, managing to run under a constant high load always improves resource utilization and can be the precursor for a comprehensive continuous improvement program. High utilization in turn leads to shorter payback times for capital investments, improving overall financial results and releasing precious cash for further fund intensive decisions.
Large Incentives for High Flexibility
Constant production is achieved by volume leveling after looking at the mean required production levels required in the medium term horizon, by product/order leveling (trying to optimize setups), or a mix of the two. The sophistication of the modern marketplace will almost certainly require a high (and always increasing) product mix, a reality that puts the pressure on for high flexibility to accommodate many different products and the shortest possible time lost in setups. Elements that go hand in hand with tight data control and analysis, clear performance metrics and solid production methodologies.
Now, let's look at some significant negative aspects of constant production.
Accommodation of Maintenance Schedules
Well trained production manpower can carry out lighter routine maintenance with great success. This usually demands short periods of time between production runs. But what about heavier scheduled maintenance that can take machines out of action for many hours? This can be a real problem for 24/7 operations and unless there is an alternative temporary product flow it can have a significantly adverse effect on productivity benchmarks. It is important to stress that the best maintenance is the predictive one. After all, unscheduled events are more harmful under very high line load and can even cause complete plant shutdowns if they last long enough to create blockages upstream or total buffer depletion downstream.
Every production line has its limits in terms of flexibility and setup times. At some point the temptation to keep productivity performance high will take a hit on flexibility. Which brings us to the third positive aspect of constant production mentioned above, where we have to find alternatives. This can be splitting the flow in different streams, separating lines by product volumes or even subcontracting part of the production volume to external partners.
Limited Capacity Signifies Other Business Shortcomings
What if lines are run constantly by force and not by choice? Such a situation could signify inadequate manufacturing planning or under-investment in the required plant equipment. What happens if orders increase? If no more shift slots are available, lines run constantly can give few answers, in which case we are looking at practically refusing new business or complicating matters with urgent subcontracting options.
The goal of achieving constant production is an attractive one, however, in order to correctly serve business needs it is important to combine strong production benchmarking with business strategic planning, reliable sales forecasting and comprehensive growth modelling. All the available data will allow high production performance coupled with a lot of open options for production fluctuations and unforeseen events.