Mitigating the risk of a new workforce by reducing rework and rightsizing on hand inventory

Dramatically increasing the hourly workforce at a rapid pace to support accelerated product demand in an aircraft manufacturing facility in a short amount of time resulted in: (1) increased rework, and (2) increased part damage during assembly. The majority of rework results from simple workmanship mistakes from the new workforce. The approach used in this thesis to combat the increase in rework involves the design and implementation of a feedback loop on the shop floor of a leading aircraft manufacturer. The loop consists of providing each worker with a list of their discrepant work from the day before and the opportunity for them to perform their own rework. The thesis shows that the percent of discrepancies reworked by the original mechanic increases from 27% to 41%. Paired data is analyzed to show (on average) a 20% decrease in rework when the feedback loop is utilized. Included is qualitative advice on implementing change on the shop floor. During final testing, damaged parts (typically as a result of out of sequence work or workmanship mistakes) are discovered and require immediate replacement. Frequently, there are no replacement parts available at the test site, since the original part was installed by a subcontractor. To meet the immediate replacement need, test personnel remove an already installed part from an aircraft upstream in final assembly at the same location. The thesis includes a case study to demonstrate a binomial demand model to estimate the amount of on hand safety stock required to prevent the unnecessary labor from the redundant part removal and replacement from upstream aircraft.

Department dc:contributor.department

Leaders for Manufacturing Program at MIT

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2009

Author dc:creator

• Larson, David (David William)

Advisor dc:contributor.advisor

• Deborah Nightingale and Stephen C. Graves.

• Sloan School of Management.
• Engineering Systems Division.
• Leaders for Manufacturing Program.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/49777

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/49777