Mechanical Processes

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BLANKING


BLANKING IS A METAL FABRICATING PROCESS, DURING WHICH A METAL WORKPIECE IS REMOVED FROM THE PRIMARY METAL STRIP OR SHEET WHEN IT IS PUNCHED. THE MATERIAL THAT IS REMOVED IS THE NEW METAL WORKPIECE OR BLANK.
CHARACTERISTICS OF THE BLANKING PROCESS INCLUDE:
  • ITS ABILITY TO PRODUCE ECONOMICAL METAL WORKPIECES IN BOTH STRIP AND SHEET METAL DURING MEDIUM OR HIGH PRODUCTION PROCESSES,
  • THE REMOVAL OF THE WORKPIECE FROM THE PRIMARY METAL STOCK AS A PUNCH ENTERS A DIE,
  • THE PRODUCTION OF A BURNISHED AND SHEARED SECTION ON THE CUT EDGE,
  • THE PRODUCTION OF BURRED EDGES,
  • THE CONTROL OF THE QUALITY BY THE PUNCH AND DIE CLEARANCE,
  • THE ABILITY TO PRODUCE HOLES OF VARYING SHAPES – QUICKLY.
THE BLANKING PROCESS FORCES A METAL PUNCH INTO A DIE THAT SHEARS THE PART FROM THE LARGER PRIMARY METAL STRIP OR SHEET. A DIE CUT EDGE NORMALLY HAS FOUR ATTRIBUTES. THESE INCLUDE:
  • BURNISH
  • BURR
  • FRACTURE
  • ROLL-OVER
THE ILLUSTRATION THAT FOLLOWS PROVIDES A TWO-DIMENSIONAL LOOK AT A TYPICAL BLANKING PROCESS. NOTE HOW THE PRIMARY METAL WORKPIECE REMAINS AND THE PUNCHED PART FALLS OUT AS SCRAP AS THE PUNCH ENTERS THE DIE. THE SCRAP DROPS THROUGH THE DIE AND IS NORMALLY COLLECTED FOR RECYCLING.


LIKE MANY OTHER METAL FABRICATING PROCESSES, ESPECIALLY STAMPING, THE WASTE CAN BE MINIMIZED IF THE TOOLS ARE DESIGNED TO NEST PARTS AS CLOSELY TOGETHER AS POSSIBLE.
THE ILLUSTRATION THAT FOLLOWS SHOWS THE WORKPIECES THAT COULD BE CREATED THROUGH THE BLANKING PROCESS USING EITHER SHEET OR ROLL AS THE PARENT MATERIAL.


THE BLANKING PROCESS HAS SOME DOWNSIDE EFFECTS. THESE INCLUDE:
  • GENERATING RESIDUAL CRACKS ALONG THE BLANKED EDGES,
  • HARDENING ALONG THE EDGE OF THE BLANKED PART OR WORKPIECE, AND
  • CREATING EXCESS ROLL-OVER AND BURR IF THE CLEARANCE IS EXCESSIVE.
THE MOST COMMON MATERIALS USED FOR BLANKING INCLUDE ALUMINUM, BRASS, BRONZE, MILD STEEL, AND STAINLESS STEEL. DUE TO ITS SOFTNESS, ALUMINUM IS AN EXCELLENT MATERIAL TO BE USED IN THE BLANKING PROCESS.
VIEW A FULL TABLE THAT MATCHES THE METALS TO THE METAL FABRICATING SERVICES WE OFFER.
TOOLING IS TYPICALLY MADE FROM TOOL STEELS AND CARBIDES, WITH THE CARBIDE TOOLING USED FOR HIGHER PRODUCTION RUNS AND INTRICATE PUNCHED SHAPES.
A BLANKING DIE CONSISTS OF A SINGLE, OR MULTIPLE, PAIRS OF MATING DIES. THE ILLUSTRATION THAT FOLLOWS SHOWS A POTENTIAL DIE SET. NOTICE THE LARGE AMOUNT OF SCRAP MATERIAL THAT IS GENERATED. TOOLS ARE EXPENSIVE FOR BLANKING SO IT IS CRITICAL THAT THE TOOLING BE CREATED CORRECTLY HOLDING TOLERANCES WHILE MINIMIZING SCRAP, THE FIRST TIME.

PUNCHING

PUNCHING IS A METAL FABRICATING PROCESS THAT REMOVES A SCRAP SLUG FROM THE METAL WORKPIECE EACH TIME A PUNCH ENTERS THE PUNCHING DIE. THIS PROCESS LEAVES A HOLE IN THE METAL WORKPIECE.
CHARACTERISTICS OF THE PUNCHING PROCESS INCLUDE:
§ ITS ABILITY TO PRODUCE ECONOMICAL HOLES IN BOTH STRIP AND SHEET METAL DURING MEDIUM OR HIGH PRODUCTION PROCESSES.
§ THE ABILITY TO PRODUCE HOLES OF VARYING SHAPES - QUICKLY.
THE PUNCHING PROCESS FORCES A STEEL PUNCH, MADE OF HARDENED STEEL, INTO AND THROUGH A WORKPIECE. THE PUNCH DIAMETER DETERMINES THE SIZE OF THE HOLE CREATED IN THE WORKPIECE.
THE ILLUSTRATION THAT FOLLOWS PROVIDES A TWO-DIMENSIONAL LOOK AT A TYPICAL PUNCHING PROCESS. NOTE HOW THE WORKPIECE REMAINS AND THE PUNCHED PART FALLS OUT AS SCRAP AS THE PUNCH ENTERS THE DIE. THE SCRAP DROPS THROUGH THE DIE AND IS NORMALLY COLLECTED FOR RECYCLING.

PUNCHED MATERIAL IS MOST NORMALLY IN SHEETS. ROLL MATERIAL CAN ALSO BE PUNCHED.
THE ILLUSTRATION THAT FOLLOWS SHOWS A FEW COMMON PUNCH AND DIE CONFIGURATIONS AND THE WORKPIECES THAT WOULD BE FORMED BY THIS COMBINATION. MULTIPLE PUNCHES CAN BE USED TOGETHER TO PRODUCE A COMPLETE PART WITH JUST ONE STROKE OF THE PRESS.



SHEARING PROCESS

SHEARING

SHEARING IS A METAL FABRICATING PROCESS USED TO CUT STRAIGHT LINES ON FLAT METAL STOCK. DURING THE SHEARING PROCESS, AN UPPER BLADE AND A LOWER BLADE ARE FORCED PAST EACH OTHER WITH THE SPACE BETWEEN THEM DETERMINED BY A REQUIRED OFFSET. NORMALLY, ONE OF THE BLADES REMAINS STATIONARY.
THE SHEARING PROCESS CHARACTERISTICS INCLUDE:
  • ITS ABILITY TO MAKE STRAIGHT-LINE CUTS ON FLAT SHEET STOCK
  • METAL PLACEMENT BETWEEN AN UPPER AND LOWER SHEAR BLADES
  • ITS TRADEMARK PRODUCTION OF BURRED AND SLIGHTLY DEFORMED METAL EDGES
  • ITS ABILITY TO CUT RELATIVELY SMALL LENGTHS OF MATERIAL AT ANY TIME SINCE THE SHEARING BLADES CAN BE MOUNTED AT AN ANGLE TO REDUCE THE NECESSARY SHEARING FORCE REQUIRED.
THE ILLUSTRATION THAT FOLLOWS PROVIDES A TWO-DIMENSIONAL LOOK AT A TYPICAL METAL SHEARING PROCESS. NOTE HOW THE UPPER SHEAR BLADE FRACTURES THE METAL WORKPIECE HELD IN PLACE BY THE WORK HOLDING DEVICES. THE SHEARED PIECE DROPS AWAY.

TYPICALLY, THE UPPER SHEAR BLADE IS MOUNTED AT AN ANGLE TO THE LOWER BLADE THAT IS NORMALLY MOUNTED HORIZONTALLY. THE SHEARING PROCESS PERFORMS ONLY FUNDAMENTAL STRAIGHT-LINE CUTTING BUT ANY GEOMETRICAL SHAPE WITH A STRAIGHT LINE CUT CAN USUALLY BE PRODUCED ON A SHEAR.
METAL SHEARING CAN BE PERFORMED ON SHEET, STRIP, BAR, PLATE, AND EVEN ANGLE STOCK. BAR AND ANGLE MATERIALS CAN ONLY BE CUT TO LENGTH. HOWEVER, MANY SHAPES CAN BE PRODUCED BY SHEARING SHEET AND PLATE.
MATERIALS THAT ARE COMMONLY SHEARED INCLUDE:
  • ALUMINUM
  • BRASS
  • BRONZE
  • MILD STEEL
  • STAINLESS STEEL
THE SHEARING PROCESS USES THREE TYPES OF TOOL SYSTEMS. THEY ARE USED FOR SHEARING:
  1. SHEET METAL AND PLATE USING A SQUARING OR BOW TIE SHEAR
  2. ANGLE MATERIALS USING AND ANGLE SHEAR, AND
  3. BAR STOCK USING A BAR SHEAR.

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