Even with laser projection and auto-jigging, assembly can still be expedited by good material handling and plating. The former can be optimized at reasonable expense, while to improve the latter will require a substantial investment. To calculate the potential impact, we can use data recorded in the benchmark testing (discussed in Part X and Part XII). Though we didn’t measure the time to move materials to the table, we learned a lot about the assembly process.
Keeping materials stocked behind truss builders is essential but preparing them properly is equally important. Cut parts should be clearly marked, stacked “last-in first out”, and supplied at table height. If saw capacity is adequate, truss parts may be grouped separately for each individual truss to further lessen material handling. They may also be divided between the left side and right side of the truss to shorten the path to the table. Truss plates should be prepicked and ideally separated as illustrated by Maple Ridge Truss in Part XII of this series. The goal is to minimize “touches” of materials. Further opportunities will be discussed in the upcoming series on cutting machinery.
The Benchmark test series provided a good breakdown of the steps in the assembly process. Shown here are the best results [See PDF or View in Full Issue], rendered at Maple Ridge Truss. Given that materials were optimally placed, and lasers and auto-jigging were employed, the only remaining time element was the proficiency of the build crew. And the Maple Ridge crew was remarkably proficient, leaving little room for improvement using existing technology, but providing a means of evaluating future investments.
Laying in materials and plating joints cost an average of about $2 per truss in this test, which was conducted under ideal conditions. Most of this labor is effectively replaced with the commercially available solutions from either Randek or Trussmatic. Both have been heavily marketed in the U.S. for at least five years, yet they have achieved little or no success. Even with twice the labor cost, say $4 per truss, would an investment in one of these systems make sense? Consider also that such systems require the additional labor of a highly skilled technician, who arguably could cost nearly as much as the three crew members these systems purport to replace. Based on this analysis, the time for highly sophisticated truss assembly machinery has yet to come.
We conclude on this 13th installment that we have reached a point of diminishing returns in automating truss assembly. Further automation may yield only marginal improvements. Given their long startup time and their ongoing maintenance expense, even the best European systems would have an unreasonably long payback. Yet our highly competitive industry will continue to test and ultimately adopt any advancement that gives them an edge. We will stay tuned. For the present, though, there’s a lot more to be gained by looking upstream and cutting costs from the cutting and material movement processes.
Next month:
Cutting Technology