DDBA 4990 Week 6 Operations Note Example

Six Hours of Work, Nineteen Days of Waiting: An Operations Note Following One Kitchen Order Through a Custom Cabinet Shop and Finding the Spray Booth That Sets the Pace for Everything Else

Student Name

Walden University

DDBA 4990: Business Essentials

Instructor Name

Month Day, Year

Six Hours of Work, Nineteen Days of Waiting: An Operations Note Following One Kitchen Order Through a Custom Cabinet Shop and Finding the Spray Booth That Sets the Pace for Everything Else

Why Follow One Order

Delay has an address in every production process, and a custom cabinet shop is no exception. Larkin Custom Cabinets, a composite shop of 18 people in the suburbs of Minneapolis, quotes kitchens at six weeks from signed drawing to installation and has delivered late on 40 percent of jobs this year. The owner believes the shop needs another cabinetmaker. This note follows one typical order, a 22-cabinet kitchen in painted maple, through the shop using a week of job tickets, and records at each step how long the work took and how long it waited before the step began.

The Process Map

The order spent about 65 hours being worked on and 19 working days waiting. Nearly half the waiting, nine days, happened in front of the spray booth.

Table 1

One Kitchen Order, Step by Step

From job tickets for order 2611, week of September 14, with waiting counted in working days.

Walking the Order Through

The quote and drawing moved quickly. Cutting waited two days for the router, which runs one shift and was busy with another kitchen. Assembly started the next morning, and two cabinetmakers finished the boxes and doors in under three days. Then the parts stopped. The shop has one spray booth, and every painted or stained piece passes through it at least three times: primer, first coat, second coat, each followed by a cure. On the day the order reached finishing, the booth already had parts from five other jobs waiting, stacked on carts along the wall. The order waited nine working days for its turn, then spent about two days in the booth. Installation followed four days later, waiting for the crew's next opening.

Why the Booth Governs the Shop

Little (1961) proved a relationship that holds for almost any steady process: the average number of jobs inside equals the rate at which jobs leave multiplied by the average time each one spends inside. Turned around, if a station finishes jobs at a fixed rate, the more work piles up in front of it, the longer each job sits there. The booth completes about three kitchens' worth of parts a week. The carts along the wall held about five kitchens' worth when the order arrived. Five divided by three is a little under two weeks, which matches the nine working days the order waited. Hopp and Spearman (2008) show how a single heavily used station can dominate the lead time of a whole line, and the booth does exactly that here: it is the only step where work arrives faster than it leaves.

What This Means for the Owner's Plan

Hiring another cabinetmaker would speed assembly, which is not where orders wait. Faster assembly would send parts to the booth sooner, making the stack along the wall taller and the wait in front of the booth longer. Goldratt and Cox (2004) told this story in novel form: improvements anywhere except the constraint add inventory without adding output. At Larkin, assembly already outpaces finishing.

Recommendations

Three changes would attack the booth directly, in rising order of cost. First, schedule the booth by job rather than by first-come parts, so that one kitchen's parts move through all three coats together instead of waiting between coats behind other jobs. Second, run the booth for a second shift three nights a week, using one finisher on overtime, which would raise its weekly capacity by about half. Third, if those changes do not bring waits in front of the booth under three days, price a second booth. The owner should not add a cabinetmaker until the booth keeps up.

What the Note Does Not Show

One week of tickets for one order is a snapshot. The waiting figures for other weeks may differ, especially in spring when kitchen orders peak. The note also does not include the time customers take to approve drawings, which the shop does not record. A month of tickets across all jobs would confirm whether the booth is the constraint year-round.

References

Goldratt, E. M., & Cox, J. (2004). The goal: A process of ongoing improvement (3rd rev. ed.). North River Press.

Hopp, W. J., & Spearman, M. L. (2008). Factory physics (3rd ed.). McGraw-Hill/Irwin.

Little, J. D. C. (1961). A proof for the queuing formula: L = λW. Operations Research, 9(3), 383-387. https://doi.org/10.1287/opre.9.3.383