Let’s face it: Machine shops, sheet metal fabricators and other manufacturers tend to look at the shop floor with rose-colored glasses.

They figure out how many production hours are theoretically available and try to backfill that figure with as much work as possible. Too often, there’s an overly optimistic view of setup times, with little margin for misplaced end mills and program prove-outs.

And routine machine maintenance is one of those cost centers that rarely if ever makes it into a job quote, let alone the time needed to replace the saw blade that failed unexpectedly or the sudden need to clean out a machine sump when the stink gets unbearable.

Reducing Tool Changeover Time: Quick-Change Tooling and Setup Optimization

Brendt Holden calls such routine machine maintenance and the other odds and ends that can take up time in a facility “the forgotten cost” of manufacturing, noting it’s where profitability quietly disappears.

As president and CEO at Haimer USA, Holden can’t solve problems related to inadequate machine maintenance. Still, he and his team can certainly help shorten lengthy setup times with an offline tool presetter.

They can also recommend any number of shrink-fit and Safe-Lock toolholders to reduce the chance of scrapping an expensive workpiece when a cutting tool slips, just as they’ll tell you that tool-life-killing vibration is often inaudible and a balancing unit will help eliminate it.

Jay Stephens, a metalworking and innovation specialist with MSC Industrial Supply, offers similar advice, noting that the company’s MillMax® technology has reduced cycle times by up to 45% in some cases. “There’s no more reliance on gut feel, intuition or experience to set cutting parameters. It’s all data-driven.”

Each of these solutions addresses one or more direct causes of manufacturing downtime. It’s usually unplanned, and in far too many shops, no one budgets for it.

Planned vs. Unplanned Downtime: Understanding the Critical Difference

This one should be obvious, yet it’s not. Simply put, planned downtime is the hour or more (sometimes a lot more) needed to set up a job and get the first part through inspection.

If the company is large enough to have a maintenance department, there’s likely some time set aside each year for routine maintenance.

Anything else is unplanned and hits the bottom line—Holden’s forgotten costs, in other words.

Calculating True Downtime Cost: Direct Labor, Overhead and Opportunity Loss

This calculation can and often does require an entire book. For readers in search of a light explanation of cost accounting, some noteworthy places to start include “The True Cost of Downtime” from Siemens.

It estimates that condition monitoring and predictive maintenance can save Fortune 500 companies 40% in maintenance costs. Your mileage may vary.

IIoT World has a page on its website titled “The actual cost of downtime in the manufacturing industry,” which cites the lengthy and quite excellent article “What is the ‘True Downtime Cost’ (TDC)?” by Business Industrial Network.

Stephens puts it simply: “When you’re removing metal, that’s when you’re making money. Anything else is more or less overhead.” It’s a statement any facilities owner would agree with.

Top 6 Causes of Manufacturing Downtime (and How to Prevent Them)

Of course, downtime comes in many shapes and sizes, but here’s a list of some heavy hitters you can pursue for quick wins:

Unbalanced Tool Assemblies: As Holden saw during a recent visit, “the operator had to reduce spindle RPM and feed rate due to vibration caused by toolholder imbalance. Now, it was taking longer than planned to make that part, and that shop lost money. That happens everywhere, every day.”

Changeover Time: This is the single greatest improvement opportunity for most high-mix, low-volume manufacturers and especially job shops. As noted earlier, Haimer provides offline tool presetting units, but savvy manufacturers can also take advantage of zero-point fixturing, quick-change tooling and more timesavers, much of it listed on this website. Reach out to one of MSC’s metalworking specialists for advice.

Tool Crib Chaos: Haimer and other solution providers offer tool management software and “smart” cabinets that streamline the tool gathering and setup process. These systems also eliminate excess or obsolete inventory, slash procurement costs and reduce the need for overnight shipments due to someone forgetting to order a critical item.

Program Optimization: “I visited a shop once that wondered why a certain cycle time varied so much from one operator to another,” says Stephens. “It turns out that someone had forgotten to remove a program stop, so the machine would sit idle if no one was there to push the green button.”

Coolant Maintenance: Stephens notes that machine shops often overlook the importance of clean cutting fluids, which are typically emulsion-based. With regular skimming, using the correct water-to-concentrate ratio, maintaining a clean sump and adhering to other best practices, facilities can avoid poor tool life and unplanned tool changes.

Unexpected Equipment Failure: All machine tools need regular maintenance. Manufacturers can extend equipment life and prevent unplanned, profit-killing downtime by keeping filters clean, topping off way lube and hydraulic fluid reservoirs and performing regular ballbar testing to ensure accuracy and detect component wear. “In addition,” says Holden, “using balanced toolholder assemblies ensures that unplanned downtime due to spindle damage will be significantly reduced.”

Preventive Maintenance ROI: Skipping Steps Now Will Cost You Later

The last one on the list is easy to overlook, and for good reason. It goes without saying that manufacturing people spend their days making parts, setting up machinery and performing all the other tasks that keep the lights on and revenue flowing.

As with the family car, who has time for an oil change?

As a result, the one task they should be performing—preventive maintenance—gets set aside, often leading to unexpected expense and weeks of downtime while the equipment is being repaired. The good news? Jay Stephens or another member of the MSC team can help.

This might mean establishing a maintenance program for cutting fluids, machine troubleshooting and spare parts support, or consulting with one of MSC’s MRO GO continuous improvement associates.

Read more: Predictive Maintenance for Manufacturing: Practical Guidance

Machine Downtime Tracking: KPIs and Metrics That Drive Improvement

Whoever you reach out to for support, it’s crucial to first establish some key productivity indicators (KPIs) by which to measure improvement efforts.

One of the most common is overall equipment effectiveness (OEE), most often calculated as availability × performance × quality. Each of these values is open to interpretation, however.

The maintenance crowd will lean toward MTBF (mean time between failure) and MTTR (mean time to repair). Reliable Plant magazine has good explainers on each.

But most manufacturers should also measure performance on first-pass inspection quality levels, on-time delivery, customer returns, adherence to schedule and so on.

Each of these and sundry others can indicate inefficiencies in the manufacturing process and therefore can be linked to unplanned downtime.

The bottom line is this: If you’re not already doing so, it’s time to turn downtime into uptime.

Video: How to Minimize Downtime in Your Shop