Mustang Sheet Fabrication Guide - Curbellplastics.com

FormingStresses Created Compared to Radiusof CornersStress-Concentration Factor3.53.02.52.01.51.0Figure 5Free Blown FormingThis is done by clamping the heated Mustangsheet and blowing upward with compressedair similar to blowing a bubble. The reverse canbe accomplished by drawing the sheet into achamber using vacuum pressureAvailability and TransportationMustang is available in fl at sheet or roll stock. Ifcutting from reels, do not re-roll to less than 50"diameter. Sheet should be handled standing onedge. Protect the entire sheet from scratches withshrink wrap or other protective source.Forming and AnnealingMustang sheet cut from reels can be thermoformedwithout annealing. However, if a flat sign will bemanufactured from Mustang cut from rollstock,annealing is recommended. Annealing can beaccomplished by placing the sheet in a forced airoven at 165º F for 2-3 hours and allowing it to coolto at least 120º F prior to use.Uniform Load Apprroximate Wind Velocity20 PSF75 MPH30 PSF90 MPH40 PSF100 MPH50 PSF130 MPHTable 3Stress-Concentration FactorForceWall ThicknessRadius0 0.2 0.4 0.6 0.8 1 1.2 1.4Radius/ThicknessSelection of Sheet ThicknessDetermining proper sheet thickness is based onthe short dimension of the sign and the specifiedmaximum wind load in pounds per square feet(PSF) (see Figure 6). The sign is required to meet aspecified wind load determined by building codesof your area. Approximate wind loads in relation towind velocity can be seen in Table 3.Short Dimensions (inches)1009080706050403020Figure 61/2"3/8"1/4"3/16"0 5 10 15 20 25 30 35 40 45 50Uniform Load, PSFSheet SizeExpansion and contraction allowances must betaken into consideration when fabricating signsfor outdoor applications. Mustang sheet, like allplastics, must be allowed to move within theconfinements of the sign channels to preventbowing or dislodging. The coefficient of linearthermal expansion (COTE) is 3.9 x 10 -5 .This number can be used to calculate thenecessary dimensions needed to allow thenecessary movement of the plastic sign face.A simple rule of thumb is to allow 1/16" perlinear foot in each direction (width and height).11