Fabrication labor and machine time estimating · Lesson 3 of 4

Fabrication labor and machine time estimating: methods and worked application

A method from operation list to documented estimate, three worked examples on one AFS profile and one run, the time formula with the learner's own times, GAO's learning-curve examples and their conditions, and the omission check.

You will be able to: Build a documented estimate from an operation list, work the operation count, sheet yield and piece count for a profile and a run, use a learning curve only where its conditions hold, and record assumptions and omissions.

10 min · 11 slides · 7 questions

All lessons in this module

Slide 1 of 11

Start with an operation list

Start with an operation list per profile: its bends, hems, the pieces in the run, and the setup, handling and checking around them.

Check the drawing against AFS's limits first, then count operations, then bring in times from your own records.

If a profile is blocked or needs shop review, stop: there is no time to estimate for a piece the shop will not make as drawn.

The method this module teaches. A profile that fails the feasibility check goes to the shop for review, not into the estimate.

Sources

GAO Cost Estimating and Assessment Guide: Best Practices for Developing and Managing Program Costs (GAO-20-195G, 12 March 2020) - U.S. Government Accountability Office
AFS fabrication limits - materials, thicknesses, bend rules and sizes the shop can make - Architectural Flashing Supply

Glossary

Operation list: This course's term for the list of work a piece needs: each bend, each hem, the pieces in the run, and the setup, handling and checking around them.
Learning curve: GAO: the premise that as the quantity produced doubles, the effort per unit declines by a constant percentage.
Slope: GAO's name for the learning curve percentage: with a 90 percent slope, a first unit of 1,000 hours means 900 hours for the second.
Drop: The width left over when whole strips are cut across a 48 in sheet; for a 6.625 in flat width it is 1.625 in.
Omission check: A pass against the drawing for work left out of an estimate, because GAO warns that some elements can be omitted by accident in a build-up.