Metrics for Lean 231

availability

The percentage of time a machine is available for production. Availability time is measured in seconds and does not include planned downtime or breaks.

bell curve

A graph of continuous data characterized by a high center, tapered sides, and flared edges. A bell curve reflects conditions that exhibit natural variation.

bottlenecks

The production process with the longest cycle time. A bottleneck process limits the flow of production and is easily identified when compared to takt time.

cell balancing

A method of matching a cell's cycle time to takt time. During cell balancing, tasks that take longer are divided and redistributed until each task requires the same amount of time.

common cause variation

A deviation that is normal and expected and that cannot be traced back to a single source. Common cause variations are sometimes called natural variations.

continuous improvement

The belief that an organization must constantly measure the effectiveness of its processes and strive to meet more difficult objectives to satisfy customers. Continuous improvement is a foundational concept in lean manufacturing.

cost of operations

A metric that looks at the overall cost of doing business across all departments rather than by individual departments. Cost of operations focuses on wise investment rather than cost cutting.

cycle time

The time it takes to perform a task and forward it to the next step. Cycle times are often tracked and monitored in lean facilities.

cycle time

The time it takes to perform a task and forward it to the next step. One of the major goals of lean is to match cycle time to takt time.

data

Factual information that is used for analysis and problem solving. Data is often in the form of values or numbers.

deviation

The difference between a standard and a result. Lean strives for zero deviation from perfection, or zero errors.

dock-to-dock time

The total time that elapses from the moment raw materials are delivered to the dock to the moment that the finished product is shipped to the customer. Dock-to-dock time, which is also known as total time of operations, is considered a broad metric.

finishing

A final process performed on a part. Finishing processes include cleaning, final sizing, polishing, and applying coatings.

first-time quality

A lean metric that indicates to what extent parts are manufactured correctly the first time without the need for rework, re-inspection, or replacement. First-time quality is considered a narrow metric.

first-time quality

A lean metric that indicates what percentage of parts are manufactured correctly without the need for rework, re-inspection, or replacement. First-time quality is considered a narrow metric.

grinding

The use of an abrasive to wear away at the surface of a workpiece and change its shape. Grinding operations commonly use abrasive grains bonded into a wheel shape.

inspection

The examination of a part to determine if it conforms to specifications. Inspection is considered a non-value added but essential activity in lean manufacturing.

inventory

The storage of raw material, in-process parts, and completed, manufactured products. Excess inventory is considered waste in lean manufacturing.

labor costs

Expenses associated with employees, including wages, insurance, taxes, and workers's compensation. Labor costs are a priority metric for traditional manufacturing companies.

lean manufacturing

An approach to manufacturing that seeks to reduce the cycle time of processes, increase flexibility, and improve quality. Lean approaches help to eliminate waste in all its forms.

machining

The process of removing material from a workpiece using cutting tools. Machining is considered a value added process in lean manufacturing.

material handling

The methods and devices used to move and store materials during the production cycle. Material handling is considered a non-value added but essential activity in lean manufacturing.

metrics

Measured variables that are tracked and can be used to detect errors or variation and make improvements. Metrics can include cycle times, inspection data, and other forms of information.

non-value added

Activities that do not contribute to the product or the process and should therefore be eliminated. Non-value added steps are waste.

non-value added but essential

Activities that support value added steps but that do not directly contribute to the product. Non-value added but essential activities can include inspection, material handling, and machine setup.

overall equipment effectiveness

OEE. A lean metric that measures how effectively equipment is being used. Overall equipment effectiveness is determined by multiplying the percentage of an equipment's availability, quality, and performance together.

overhead

Expenses associated with operating buildings and equipment, including rent, insurance, utilities, and repairs. Traditional manufacturing companies try to reduce overhead as much as possible.

performance rate

The rate parts are produced divided by the machine capacity. Performance rate includes the number of parts produced in a given time, reduced speeds, idling, and short-term stoppage for jams and other problems.

productivity metrics

Data used to gauge performance. Metrics can be used to detect errors and track an operation's progress.

pull systems

A material management system in which parts are not delivered to machines until they are needed. Pull systems are based on actual demand for parts.

quality rate

The percentage of good parts out of the total number of parts produced. Quality rate includes time lost to defects and the time it takes from startup to normal production.

retooling

Changing machinery, fixtures, and tools for the production of a new product. Retooling takes place before new product runs begin.

root causes

The origin of an error problem. To identify root causes, manufacturers must study narrow metrics.

single minute exchange of dies

SMED. A theory of setup reduction that strives to reduce the time it takes to perform product changeover to under ten minutes. Single-minute-exchange of dies can help reduce cycle time.

special cause variation

A deviation that causes an undesirable, fundamental change in a process. Special cause variation, which is also known as unnatural variation, can be traced back to a single source.

takt time

The rate at which a customer requires a company to manufacture products. Takt time is the number of work minutes per day divided by the number of orders per day.

takt time

The rate at which a customer requires a company to manufacture products. Takt time is the number of work minutes per day divided by the number of units ordered per day.

takt time

The rate at which a customer requires a company to manufacture products. Takt time is the number of work minutes per day divided by the number of work orders.

total time of operations

The total time that elapses from the moment raw materials are delivered to the dock to the moment that the finished product is shipped to the customer. Total time of operations, which is also known as dock-to-dock time, is considered a broad metric.

value

A real or perceived quality that satisfies the needs and wants of a customer. Value includes the features of a product, as well as other qualities associated with the product.

value added

Any part of the production process that improves the product for the customer. For a process to be considered value added, a customer must be willing to pay for it.

variation

Any change from what is normal and consistent. Variation can be identified as either common cause variation or special cause variation.

waste

Any thing or process that does not add value to a product. Scrap is the most common form of waste.

wheel dresser

A sharp, elongated tool that is held against a spinning grinding wheel for sharpening. Wheel dressers are often embedded with diamonds.

work cell

An arrangement of machines, tooling, materials, and operators structured around the design of similar products. Work cells encourage smooth product flows and use space efficiently.