A conical bifurcation (Pants) with different and angle-designed outlets need to be manufactured quickly by the maintenance department. This bifurcation makes part of a dust extraction system

Overall dimensions

- Entering diameter1: 450mm
- Entering diameter2: 550mm
- Outlet diameter1: 750mm

Let’s see 4 comparing methods for the unfolding of this piece:

Method 1: Defining the tracing by the boiler designer over the metal sheet.

Average tracing time considering:
16 divisions per opening and experience on this piece format = 240min.

Additional disadvantages

- Low number of divisions (16) to reduce the time, causing non-precise and irregular openings for welding;

- Final shape displacement due to geometric calculation process at 1:1 ratio on the metal sheet, causing accumulation of small errors on compass opening and transfer of parallels;

- Possibility of errors due to excess of parallels, perpendiculars, joints of arcs and defined points over the metal sheet;

- Difficult to identify actual position of the last points leading these point to remain out of the metal sheet area or result in a non-efficient sheet nesting;

- Excess requirement of skilled employees.

Method 2: Defining the tracing by designers (on the plane table) and further marking on the metal sheet points.

Average time to perform the scale tracing considering: 16 divisions per opening and designer experience on this piece format = 100 min + 30 min to mark the points.

Additional disadvantages :

- Low number of divisions (16) to reduce the time, causing non-precise and irregular openings for welding;

- Final shape displacement; smaller if compared to the previous process. However, the scale calculation leads to error due to precision reduction and due to the scale selected for the calculation;

- Possibility of errors due to excess of parallels, perpendiculars, joints of arcs and defined points over the drawing;

- Excess requirement of skilled employees.

Method 3: Defining the tracing by designers (in CAD) and further marking on the metal sheet points.

Average time to perform the scale tracing considering: 16 divisions per opening and designer experience on this piece format = 45 min + 30 min to mark the points.

Additional disadvantages :

- - Low number of divisions (16) to reduce the time, causing non-precise and irregular openings for welding;

- Possibility of errors due to excess of parallels, perpendiculars, joints of arcs and defined points over the drawing;

- Excess requirement of skilled employees.

Calculation with CALDsoft and further marking of the metal sheet points

1 min + 30 min to mark the points

- Possibility of using a high number of divisions;

- Error-free calculation due to analytic geometric method (and non-generic descriptive);

- Skilled employee in Boiler designing is not required;

- It can be calculated by a maintenance mechanic or boiler designer once the program is easy to use and it is fully available in Portuguese;

- Thew unfolded pieces can be viewed over the available metal sheet. Hence, reducing scraps.

Pratical comparison

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