How to Tackle the Six Big Losses in Manufacturing with Digital Layered Process Audits

Manufacturing leaders charged with improving overall equipment effectiveness (OEE) and total productive maintenance (TPM) face a complex challenge, and it’s not always clear where to start.

At the heart of the problem sit the Six Big Losses in manufacturing processes, which is simply a way of categorizing manufacturing losses that impact the individual components of OEE.

One way manufacturers can uncover and prevent the Six Big Losses is with layered process audits, a high-frequency plant floor auditing technique focused on process inputs. These audits take place every day, even as often as every shift, providing opportunities for observation, feedback, preventing slow cycles, and increasing productivity.

To see how, let’s dive in with a closer look at the Six Big Losses, their underlying causes and what plant floor checks should focus on to prevent them.

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What Are the Six Big Losses?

The Six Big Losses describe common types of manufacturing losses that result in a reduction in overall equipment effectiveness (OEE). Each of the losses relate back to a specific OEE variable (availability, performance and quality rate). By analyzing the Six Big Losses, manufacturers can pinpoint specific improvements that will help increase OEE.

OEE variable	Six Big Losses
Availability	·   Equipment failure ·   Machine setup
Performance	·   Minor stoppages ·   Reduced operating cycle time
Quality	·   Scrap ·   Rework

How to Address the Six Big Losses in Lean Manufacturing:

Avoid Equipment Failure, Optimise Machine Setup and Adjustments

Reducing Availability Loss

Availability is defined as the percentage of planned operating time that a machine or plant actually runs. Availability losses include both planned and unplanned stops as shown in the table below.

Planned stops	Unplanned stops
Scheduled maintenance	Equipment breakdowns
Tooling or machine changeovers	Tooling failure
Equipment adjustments	Upstream or downstream bottlenecks
Machine warmup time	Lack of operators or materials

Manufacturers can use layered process audits to increase availability by verifying items such as whether:

• Operators perform autonomous maintenance
• Operators have the right tools, and those tools work correctly
• Workstations are blocked by upstream or downstream bottlenecks
• Systems for requesting additional materials are working efficiently

Reducing Performance Loss

Performance rate is defined as how fast a machine runs in comparison with its optimum speed. Performance loss comes from minor stops as well as less than ideal cycle time (reduced operating cycle times).

Performance losses	Common causes
Minor stoppages (less than a few minutes)	·   Equipment jams or misfeeds ·   Incorrect machine settings ·   Issues with equipment sensors ·   Stopping to clean equipment
Reduced operating cycle time	·   Machine or tooling condition ·   Startup and shutdown ·   Material quality issues ·  Operator inexperience

Here, layered process audits can help identify sources of performance loss by asking questions such as whether:

• Equipment settings are correct
• Operators can describe and demonstrate steps in the process to gauge training effectiveness
• There are any issues with incoming materials slowing the process down
• Operators encounter any machine issues frequently, such as equipment jams or sensor issues
• Machines and tools are in good condition

Reducing Quality Loss

Quality rate is defined as the number of good parts produced compared with the total number manufactured. It is a direct function of defects, which can have a variety of causes. Some of the most common are incorrect machine settings and operator error, as well as startup rejects that occur at the beginning of the shift or after changeover.

Layered process audits are a powerful tool for reducing manufacturing defects. By checking daily that operators are following standard work and key machine settings are correct, manufacturers can proactively identify sources of quality loss so they can better prevent it.

For example, layered process audits can help verify that:

• Operators correctly execute critical-to-quality steps in a specific procedure
• Machine settings are correct
• Incoming materials meet key quality specifications
• Previous corrective actions are held in place

Why Going Digital Matters to Improve OEE and TPM

Conducting layered process audits—or simply performing plant floor checks more frequently—can unlock a wealth of information for improving availability, performance and quality rate. However, upping the frequency of audits does come with its own challenges, particularly if you rely on pen-and-paper or spreadsheets.

A digital plant floor audit platform like EASE eliminates the challenges of traditional auditing by allowing you to:

• Schedule a large number of audits with just a few clicks
• Automatically notify people when it’s time to do their audits, or escalate to managers when people miss them
• Conduct audits on mobile devices and immediately upload results to the system
• Flag problems and track them to closure for greater visibility into issues

Improving OEE is a complex task, one that requires understanding the variables that go into it and how they are impacted by the six big losses. Conducting frequent plant floor checks like layered process audits can help address these losses to promote leaner, more reliable and more productive plant operations.