Typical Brake Sizing
Material Unwind Operations
Sizing Specifications
Full roll diameter (in.) (FD) = 6 in.
Core diameter (in.) (CD) = 4 in.
Average Tension (lbs.) (T) = 4 lbs.
Velocity (feet per min.) (V) = 100 fpm
Sizing Formula
Average radius (in.) = (FD+CD) / 4 = (6+4) / 4 = 2.5 in.
Torque (in. lb.) = (T) x Avg. Rad. = 4 x 2.5 = 10 in. lb.
Check Tension Range
Maximum Tension = Torque x 2 / CD (10×2 / 4) = 5 lbs.
Minimum Tension = Torque x 2 / FD (10×2 / 6) = 3.3 lbs.
Slip Watts = Max. Tens. x V / 44.2 (5×100 / 44.2) = 11.3 watts
Specify: Model SMB-12
Coil Wind Operations
Sizing Specifications
Pulley/Nip Roll dia. (in.) (D) = 6 in.
Tension (T) = 6 lbs.
Velocity (V) = 100 fpm
Sizing Formula
Torque (in. lb.) = TxD / 2 = (6×4) / 2 = 12 in. lb.
Slip Watts = TxV / 44.2 = (6×100) / 44.2 = 13.6 watts
Specify: Model SMB-12
If diameter is not predetermined, calculate slip watts and select a unit with a sufficient dissipation rating. Determine maximum diameter of pulley or nip roll using the following equation: Max. dia. (in.)=(12 in.lb.x2) / 6 lbs. = 4 in.
Material Handling Operations
Motor Horsepower Method
Motor HP = 1/2 HP
Motor RPM = 1750 RPM
Sizing Formula
Torque (in. lb.) = HP x 63000 / RPM
1/2 x 63000 / 1750 = 18 in. lb.
Specify: Model SMB-60
Tightening Operations
Sizing Specifications
Slip RPM = 500 RPM
Torque = 8 in. lbs.
% Slip Time of total cycle time = 25%
Sizing Formula
Watts = .0118 x Torque (in. lb.) x Slip RPM x % Slip Time
.0118 x 8 x 500 x .25 = 11.8 watts
Specify: Model SMB-60
Contact Us
Sjogren is back at Interwire 2025!
Join us as at Interwire 2025 as we unveil our latest machinery and tools in wire processing technology, featuring interactive product models and exclusive demonstrations. May 13-15, 2025
In Memory of Carl P. Sjogren
in loving memory of Carl P. Sjogren
NEW MACHINE! – Matsuura MAM72-35V PC-32
Sjogren has long been an industry leader and continues to deliver customized, factory-floor innovations that provide some of the greatest efficiencies in the field. We have recently added some new equipment to our facility, including a Matsuura MAM72-35V PC-32. You...