Sheet Metal Forming

12 / Sheet Metal Forming—Processes and Applications
1.6 Ultra-High-Speed Blanking
Ultra-high-speed (UHS) blanking refers to 
punch velocities greater than 5 m/s (16 ft/s). 
Ultra-high-speed blanking can provide sheared 
edge quality almost similar to fine blanking at a 
lower cost. Typical punching operations un-
dergo three phases: elastic, plastic, and fracture. 
At very high speeds, the material bypasses the 
elastic and plastic phases, and rolled edges and 
burrs do not have the time to be formed.
Adiabatic Phenomenon.
 
During UHS blank-
ing, the punch hits the blank with high velocity 
that produces an adiabatic band in the punch line 
of the sheet material. The result is a strong tem-
perature increase in the adiabatic zone during a 
very short time (100 µs) (Ref 1.14). During this 
process, the heat produced has no time to dissi-
pate as quickly as it is being generated. The ma-
terial softens instantly (known as adiabatic soft-
ening), and the produced adiabatic shear bands 
can split both soft and hard materials. During 
adiabatic blanking, because the part is strongly 
accelerated by the punch impact, its own inertia 
force contributes to the blanking process. The 
adiabatic blanking process requires high ac-
celeration and deceleration values (10,000 to 
100,000 m/s
2
, or 32,800 to 328,000 ft/s
2
) because 
of high velocity and small stroke length. The de-
sign also must take into account the kinetic en-
ergy of the moving parts as well as potential re-
bounds and vibration. 
Advantages and Applications of UHS 
Blanking.
 
The advantages of UHS blanking 
over conventional blanking in terms of part 
quality include:
•
Reduced
or nonexistent burr height
•
Decreased rollover
•
Lesser distortion 
Further advantages of the technology include: 
•
Dry, oil-free cutting process
• Reduction of finishing processes 
High-speed blanking has been used to manu-
facture blanks for coins or circular blanks for 
aluminum packaging applications. Product ma-
terial applications include aluminum and rela-
tively soft alloyed materials, such as brass or 
bronze, up to very hard materials, such as nickel 
or special/stainless steels. The process is now 
also extended to harder materials, wider strips, 
higher production rates, and even the manufac-
ture of bimetal rings—all of which require 
higher press capacities.