OPS 385 Week 1 Value, Waste and Lean Thinking Example

Eleven Days for Forty Minutes of Work: Value, Waste and Lean Thinking at a Memphis Starter and Alternator Remanufacturer

[Student Name]

University of Phoenix

OPS/385: Lean Six Sigma and Process Management

Week 1 Assignment

[Instructor Name]

[Date]

Delta Rebuild Industries, its process, times and figures are composites written for a model paper.

Delta Rebuild Industries is a composite remanufacturer in Memphis, Tennessee, employing about 110 people. It rebuilds starters and alternators for heavy trucks, buses and farm equipment, selling to fleet operators and parts distributors in the mid-South. Customers send in worn units, called cores, which Delta disassembles, cleans, inspects, machines where needed, rebuilds with new bearings, brushes, regulators and other parts, tests, paints and ships back or sells from stock. Its largest fleet customer, a regional freight carrier with about 1,800 trucks, has complained that alternators sent for rebuilding take eleven working days to return, while a competitor now promises five. This paper applies lean thinking to Delta's alternator process.

Value From the Customer's View

Lean thinking starts by defining value as the customer would. Womack and Jones (1996) set out five lean principles: specify value from the customer's perspective, identify the value stream, make value flow, let the customer pull and pursue perfection. For the freight carrier, value means an alternator that performs like a new one, arrives within a predictable time, carries a warranty and costs about half the price of new. Nothing else Delta does adds value unless it contributes to one of those. Interviews with the carrier's maintenance manager added one more element: trucks waiting for an alternator sit idle, so speed is part of value, not a convenience.

Mapping the Value Stream

The team followed one batch of alternators through the plant, recording process time, the time a unit is actually worked on, and waiting time at each step:

Core receiving and sorting: 4 minutes of work; cores wait about 2 days in a sorting area before being matched to orders.

Teardown: 8 minutes; parts wait about 1 day for a cleaning batch.

Cleaning: 6 minutes in the parts washer; batches of 50 wait about 1.5 days for inspection.

Inspection and measurement: 5 minutes; units wait about 1 day for machining.

Machining of shafts and slip rings where needed: 4 minutes average; wait about 1.5 days.

Rebuild and assembly: 12 minutes; wait about 1.5 days for test.

Testing on the alternator test bench: 3 minutes; wait about 1 day for paint.

Painting and drying: 2 minutes of work, 2 hours drying; wait about 1 day.

Packing and shipping: 2 minutes; waits for the next carrier pickup, about half a day.

Total process time is about 46 minutes. Total lead time is about 11 working days.

Process Efficiency

Process cycle efficiency compares value-adding time with total lead time. Even counting all 46 minutes as value-adding, which is generous, the efficiency is 46 minutes divided by about 5,280 working minutes, or under 1 percent. Units spend more than 99 percent of their time waiting. Shah and Ward (2007), developing measures of lean production, described lean as an integrated system aimed at producing with minimal waste through practices that reduce variability in supply, processing time and demand. Delta's map shows a process built around batches and queues rather than flow.

An alternator spends forty-six minutes being rebuilt and eleven days waiting its turn.

Classifying Activities

Value-adding: teardown, machining where needed, rebuild and assembly, painting, since the customer pays for a restored, protected unit.

Necessary but not value-adding: testing and inspection, required to assure a working unit and support the warranty; cleaning, needed to inspect and rebuild.

Pure waste: waits between steps, moving batches across the plant, searching for parts and re-sorting cores.

The Eight Wastes on Delta's Floor

Transportation: batches of 50 units move about 900 feet across the plant on carts, since cleaning and machining sit at opposite ends.

Inventory: about 1,600 cores sit unsorted in the receiving area, and work in process between steps averages about 400 units.

Motion: rebuilders walk to a central parts crib for bearings and brushes several times an hour.

Waiting: every step waits for a full batch of 50 from the previous step.

Overproduction: the plant rebuilds popular models for stock while customer orders wait.

Overprocessing: every shaft goes through measurement twice, at inspection and again at machining.

Defects: about 7 percent of units fail the final test and return to rebuild.

Unused talent: rebuilders have ideas about fixtures and parts kits but no process to share them.

Why the Batches Grew

No one designed the plant to make units wait. Batches of 50 grew from a reasonable idea: the parts washer uses the same heated solution and cycle time whether it holds ten parts or fifty, so washing fifty at a time looked efficient. Machining set its own batches to reduce changeovers between shaft sizes. Each department optimized its own step, measured by units processed per labor hour, and the result was a plant in which every step waits for the one before it to finish a large batch. Lean thinking asks the opposite question: not how busy each step is, but how quickly a customer's unit moves through all of them.

First Steps Toward Flow

Three changes come first. Cut cleaning and transfer batches from 50 to 10, which the parts washer can handle with shorter cycles, reducing waits between steps. Move the test bench beside rebuild and use a simple pull signal: rebuild starts a unit only when a test slot opens, so work does not pile up. Sort cores within one day of receipt and match them to orders before stock rebuilds, so customer units go first. A rough estimate suggests these alone could cut lead time from eleven days to about five.

Further Opportunities

Parts kits delivered to rebuild benches would remove motion; a combined inspection and machining cell would remove one measurement step and one transport. The test failure rate, at 7 percent, is a quality problem that later weeks will address with Six Sigma methods. Snee (2010) described Lean Six Sigma as a combination in which lean methods attack waste and slow flow while Six Sigma reduces variation and defects, each covering the other's blind spots; Delta's map shows it needs both.

Conclusion

For Delta's fleet customers, value is a working unit, quickly and predictably returned, at a fair price. Mapping the alternator value stream shows 46 minutes of work spread across eleven days, with waste in all eight categories. Smaller batches, a pull signal at test and faster core sorting are the first steps toward flow, and the defects found at test set up the improvement project to come.

References

Shah, R., & Ward, P. T. (2007). Defining and developing measures of lean production. Journal of Operations Management, 25(4), 785-805. https://doi.org/10.1016/j.jom.2007.01.019

Snee, R. D. (2010). Lean Six Sigma: Getting better all the time. International Journal of Lean Six Sigma, 1(1), 9-29. https://doi.org/10.1108/20401461011033130

Womack, J. P., & Jones, D. T. (1996). Lean thinking: Banish waste and create wealth in your corporation. Simon & Schuster.