Downtime, the term coined to reflect when a production line is not producing product, is estimated by The International Society of Automation (ISA) to cost the manufacturing industry nearly $650 billion every year. While downtime can occur at any point in a production process, we’ll explore what producers can do to help minimize the risk and impact of downtime in the packaging phase of production.
Good packaging machine and automation design works to prevent planned or unplanned downtime, and packaging process analysis can help identify potential downtime risks and improvement opportunities. Equipment designs that minimize the impact of tool changeovers, consumable replenishment, washdown, and other planned maintenance activities are an important piece of this puzzle. However, the unpredictable nature of unplanned downtime combined with many interrelated causation factors makes this a cause-célèbre for most producers.
The true cost of downtime
Quantifying downtime is relatively straightforward: take the difference between planned and actual operating times, multiply average production rate by the total downtime and apply the gross profit per unit to get a reasonably accurate picture of the operational costs you incur when your lines are down.
Well, not so fast… Idle staff and lost capacity amplify that figure, and the ripple through effect on labor can add up. Did you account for maintenance staff cycles? In addition to idle machine operators, there may be staff loading or preparing the product to get to the line, and case packing on the backside of it — did they go idle?
Costly, prolonged unplanned downtime is more common in organizations with a reactive maintenance strategy. Proponents cite that running machines until they fail maximizes tooling or machine component utilization. However, reactive strategies tend to focus staff on the symptoms versus the root causes of downtime. In addition, it is not uncommon for equipment breakdowns to result in collateral damage, taking out associated systems or resulting in a cascade of related machine failures. While potentially acceptable for highly reliable equipment or when machine parts are cheap and easily replaced, most producers see a net uptime benefit from a proactive, planned downtime strategy for machine parts replacement and equipment servicing.
Unlike unplanned downtime, planned downtime for equipment maintenance or consumables replacement is a scheduled event. Proactive, planned maintenance strategies have been shown to improve overall OEE/capacity utilization, a factor in defraying or delaying capital expenses of additional equipment.
When comparing the cost of a proactive versus reactive strategy, don’t forget to account for the cost of replacing parts with useful lifespan remaining, as well as maintaining spare parts inventories.
Are you placing the blame where it belongs?
Your team’s ability to identify and accurately assign the root cause behind unplanned downtime events is perhaps one of the most impactful contributions they can make to improving your packaging line’s Overall Equipment Effectiveness (OEE), a commonly used KPI that benchmarks how close your line is to its theoretical maximum production capability.
In a real-world example, a senior manager at a ground beef plant called for service when his thermoforming line ran at 50% OEE for four hours of a 16-hour shift. Upon examination of the downtime reports, it was quickly determined that the line had been starved of product for two hours. As you might surmise, no packaging line will perform if you’re not putting product into the system! In this case, citing equipment failure essentially ignored the prior stoppage in the grinding room. While it seems obvious, we often find that how a team measures which equipment is down can contribute to longer than necessary downtime.
In another example, a major cheese producer reported a spate of downtime events in their packaging machines — there were a fair amount of line stops and even some tool crashes. A quick process review revealed that the weigh scales were making double dumps, overfilling product, or leaving it all together empty — all of which will result in some type of equipment fault or tool crash within the packaging machine.
In both cases, assigning downtime to the packaging machine, rather than a pre-loading process, resulted in preventable delays bringing the line back into expected performance parameters.
Training operators to better explore and identify process-related cause and effect to ascertain the most likely source of a downtime event is one of the common recommendations we make to help customers minimize the duration of unplanned downtime.
One of the more interesting developments in recent years is the rise of augmented reality for both training and on-the-job support — a topic deserving future exploration on its own.
Avoiding the domino effect
In automated and semi-automated multi-stage lines, where loading, inspection, conveying and secondary/tertiary packaging systems are strung together, the key concept to remember is “decoupling”. A process flow that accommodates the storage and use of buffer stock at key points keeps the entire line from becoming unproductive should one phase of the packaging process need to be stopped. If you’ve owned older holiday lights wired in series, you can relate — when one bulb fails or is removed the entire string stops working. The ability to decouple the packaging loading process at key points allows production to continue by drawing on buffer stock while film is replaced, tools changed out, or repairs made.
An ounce of prevention versus a pound of cure?
A lot of packaging line downtime — planned or unplanned — can be influenced by equipment design. As the saying goes, “an ounce of prevention is worth a pound of cure.” Yet another relevant and appropriate colloquialism might be, “pay me now or pay me later.” Good design can diminish many of the common causes of unplanned downtime, albeit usually with a higher upfront purchase price. We advocate making decisions based on machine total cost of ownership (TCO) rather than one-time acquisition costs. TCO accounts for the soft (but real) costs associated with downtime, such as replacement parts, tool serviceability, and consumable usage.
Now let’s examine a few design considerations that can make a real difference in your efforts to minimize downtime:
A robust frame improves stability. All machines lift large tools up and down, have transport arms to go forward and back, and generate sealing pressure. A solid design made from steel experiences less operational vibration.
Vibration creates excessive component wear over time, setting the stage for unplanned failures as a result of metal fatigue, wires that loosen, or bearings that get out of round. In some machines a little bit of slop in the bearings can impact product placement, which can lead to tool crashes. Does the machine require water cooling (something else to go wrong) or is it air cooled? Finally, it is also intuitive that expected machine longevity is directly correlated with construction quality.
Few producers recognize the true cost of using compressed air-actuated devices versus electromechanical servos. Even new pneumatic systems are inconsistent: air pressure is generated with a compressor, which must be piped to the machine, so there’s always some transfer loss which impacts operation. In older systems vacuum system leaks are common — gaskets and cylinders must be oiled and repaired often. Incorrect air pressures are a common downtime instigator, whereas servo-driven designs operate consistently every time.
Spare parts and service
The question isn’t whether they’re available — it’s how fast, and at what cost. Proprietary parts, only available from only the OEM, quickly become a flash point for staff ire. Speed and ease of parts and service personnel availability, the cost of maintaining a reliable in-house spares inventory have direct impact on recovering from downtime events.
Equipment subject to regulatory oversight is designed to protect against intrusion of solids and liquids. Sanitary equipment design elements include everything from pitched frames to encourage run off, to electrical and pneumatic component housing. Machines are IP rated for electrical and pneumatic enclosures protection.
However, not all designs are equally effective.
Evaluate placement of circuit boxes, cabinets, or any other enclosed structure on the machine for both protection and ease of access during maintenance. For instance, an electrical component cabinet placed underneath a machine frame rather than on top has a higher probability of eventually malfunction or failure due to liquid intrusion — and those on top are far easier and faster for maintenance teams to access.
Tools and consumables
All OEMs today recognize the importance of simple, fast tool changeovers and rapid consumable replenishment when it comes to planned downtime, but execution varies widely. It pays to compare vendor strategies, including tool complexity.
Simplicity of design
It sounds trite, but elegance is complexity made simple. Look for ease of access to machine components, a minimum of moving parts, and replacement of electro-mechanical functions with digital technologies. All of these factors contribute to better uptime performance.
You can do it!
The bad news is that until machines can repair themselves, you need to consider downtime during the equipment selection process. Doing so will drive down the frequency, severity, and impact of future downtime events and improve your OEE performance on a consistent basis.
Want to learn more about avoiding downtime? Let us help! You can read our guide to enhancing OEE on the packaging line, or contact us today to schedule a conversation with an experienced packaging product manager.