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BASICS OF WIRE ROPE
- TYPICALLY WIRE ROPE MAY CONTAIN HUNDREDS OF INDIVIDUAL WIRES ENGINEERED TO OPERATE AT CLOSE BEARING TOLERANCES TO ONE ANOTHER. WHEN WIRE ROPE BENDS THE WIRES SLIDE AND ADJUST IN THE BEND TO ACCOMMODATE THE DIFFERENCES IN LENGTH BETWEEN THE INSIDE AND OUTSIDE OF THE BEND. THE SHARPER THE BEND, THE GREATER THE MOVEMENT.
- EVERY WIRE ROPE HAS THREE BASIC COMPONENTS: 1)WIRES WHICH FORM THE STRANDS, 2)THE STRANDS, WRAPPED HELICALLY AROUND THE CORE OR CENTER, AND 3) THE CORE, WHICH FORMS THE FOUNDATION FOR THE STRANDS.
- THE CENTER OF THE WIRE ROPE , OR CORE IS AN INDEPENDENT WIRE ROPE CORE (IWRC), WHICH ACTUALLY IS A WIRE ROPE ITSELF.
- THE GREATEST DIFFERENCE IN WIRE ROPES ARE FOUND IN THE NUMBER OF STRANDS, STRAND CONSTRUCTION, THE SIZE OF THE CORE, AND THE LAY DIRECTION OF THE STRANDS VERSUS THE CORE.
- WIRES OF WIRE ROPE ARE MADE FROM HIGH CARBON STEEL. THESE CARBON WIRES CAN COME IN VARIOUS GRADES. THE TERM “GRADE” IS USED TO DESIGNATE THE STRENGTH OF THE WIRE ROPE. WIRE ROPE TODAY IS GENERALLY FABRICATED TO MEET THE STANDARDS OF EXTRA IMPROVED PLOW STEEL (EIPS), OR EXTRA EXTRA IMPROVED PLOW STEEL (EEIPS) STANDARDS. VISUALLY IT IS IMPOSSIBLE TO DETERMINE WHAT GRADE YOUR WIRE ROPE IS, MILL TEST REPORTS CAN BE PROVIDED FROM THE FACTORY TO DETERMINE WHAT GRADE OR STRENGTH . IMPORTED WIRE ROPES CAN BE DIFFICULT TO OBTAIN MILL TEST REPORTS, DOMESTIC WIRE ROPE MANUFACTURERS CAN READILY PROVIDE MILL TEST REPORTS.
- CONSTRUCTION: EXPRESSED IN NUMBERS OF STRANDS X NUMBER OF WIRE. 6X25 INDICATES THE WIRE ROPE CONSISTS OF 6 STRANDS, WHICH HAVE 25 INDIVIDUAL WIRES. CONSTRUCTIONS CAN BE GROUPED IN CLASSES:
- 6X19 CLASS: CONTAINING 6 STRANDS THAT ARE MADE UP TO 15 THROUGH 26 WIRES, WITH NO MORE THAN 12 OUTER WIRES. ( BRIGHT OR UNCOATED) THIS WIRE ROPE HAS A GOOD BALANCE BETWEEN ABRASION RESISTANCE AND FATIGUE RESISTANCE, IN RELATION TO OTHER ROPES.
- 6X37 CLASS: CONTAINING 6 STRANDS THAT ARE MADE UP TO 27 THROUGH 49 WIRES, WITH NO MORE THAN 18 OUTSIDE WIRES. (BRIGHT OR UNCOATED)
- 8X19 CLASS: CONTAINING 8 STRANDS THAT ARE MADE UP OF 15 THROUGH 26 WIRES, WITH NO MORE THAN 12 OUTSIDE WIRES. (BRIGHT OR UNCOATED)
- 19X7 CLASS: CONTAINING 19 STRANDS, EACH STRAND IS MADE UP OF 7 WIRES. 8X19, 19X7 HAVE ROTATION RESISTANT QUALITIES.
- 7X7, 7X19 GALVANIZED WIRE ROPE, REFERRED TO IN OUR MARKET AS “AIRCRAFT” CABLE, NOT TO BE USED FOR AIRCRAFT AND IS NOT CABLE, BUT WIRE ROPE. (STAINLESS STEEL IS ALSO AVAILABLE, TYPE 304, 316)( PRE-CUT REELS OF 250, 500, 1000, AND 5000FT ARE AVAILABLE )
- 1X7, 1X19 STRANDED WIRE ROPE
- 7X7X7, 7X7X19 CABLE LAID WIRE ROPE, EXTREMELY FLEXIBLE.
- LANG LAY, LEFT LAY, ALTERNATE LAY ARE AVAILABLE BY REQUEST. HEAVY LUBRICATION AVAILABLE BY REQUEST.
- 7X7, 7X19 AVAILABLE IN NYLON COATINGS, OR PVC COATED WIRE ROPES.(SOME COLORS ARE AVAILABLE, BUT STANDARD COLOR IS CLEAR.
- REFERENCE FEDERAL SPECIFICATION RR-W-410D FOR LUBRICATION REQUIREMENTS FROM THE FACTORY. DIMENSIONAL AND CAPACITY MEETS THE STANDARDS FROM MIL-W-83420E.
LISTS OF CAPACITIES ARE FOR COMPARISON ONLY, OPERATING LOAD CAN VARY, NEVER EXCEED THE RECOMMENDED DESIGN FACTOR, OR 20 PERCENT OF CATALOG BREAKING STRENGTH
WIRE ROPE INSTALLATION, STORAGE
INSPECT AND VERIFY CORRECT DIAMETER OF THE WIRE ROPE, BEFORE INSTALLATION. THIS IS TO INSURE THAT THE CUSTOMER HAS THE CORRECT WIRE ROPE FOR THE PROJECT, OR MACHINE AND EQUIPMENT.
- STRESS WILL BE MUCH HIGHER IN AN UNDERSIZED WIRE ROPE, THE CHANCE THE ROPE WILL BREAK IS INCREASED.
- OVERSIZED WIRE ROPE WILL WEAR OUT PREMATURELY , WEARING INCORRECTLY ON THE SHEAVES (PINCHING IN THE GROOVES OF THE DRUM)
- NEVER STORE WIRE ROPE IN AREAS SUBJECT TO ELEVATED TEMPERATURES. DUST AND GRIT OR CHEMICALLY LADEN ATMOSPHERES SHOULD BE AVOIDED.
- STORED COILS OR REELS OF WIRE ROPE SHOULD BE LUBRICATED, IN ADDITION TO WHAT THE FACTORY APPLIES.
- CARE MUST BE TAKEN WHEN REMOVING WIRE ROPE FROM THE SHIPPING PACKAGE, AS WIRE ROPE CAN BE PERMANENTLY DAMAGED IF NOT UNREELED OR UNCOILED CORRECTLY.
- PULLING ON LOOPS CAN CAUSE KINKS IN THE ROPE, DAMAGING THE WIRE ROPE PERMANENTLY.
- KEEP OUT FROM UNDER A RAISED LOAD!! DO NOT OPERATE THE LOAD OVER PERSONNEL. DO NOT RIDE ON THE LOAD. CONDUCT ALL LIFTING OPERATIONS IN A MANNER THAT IF THE RIGGING WAS TO FAIL, NO PERSONNEL WOULD BE INJURED.
- WIRE ROPE THAT IS FOUND TO NON-COMPLIANT SHOULD BE DESTROYED, RATHER THAN DISCARDED. USED WIRE ROPE MIGHT BE USED BY SOMEONE THAT IS UNAWARE OF THE HAZARDS ASSOCIATED WITH THE APPLICATION.
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BASIC INFORMATION ON WIRE ROPE
WIRE ROPE IS A MACHINE, BY A DICTIONARY DEFINITION: “ASSEMBLAGE OF PARTS… THAT TRANSMITS FORCES, MOTIONS, AND ENERGY FROM ONE TO ANOTHER IN SOME PREDETERMINED MANNER, WITH A DESIRED END RESULT.
A TYPICAL WIRE ROPE CAN CONTAIN HUNDREDS OF WIRES WHICH CAN BE FORMED AND FABRICATED TO OPERATE WITHIN CLOSE TOLERANCES TO EACH OTHER. WHEN WIRE ROPE BENDS, EACH OF THE WIRES SLIDES AND WILL ADJUST IN THE BEND TO ACCOMMODATE THE DIFFERENCE IN THE LENGTH BETWEEN THE INSIDE AND THE OUTER BEND. THE SHARPER THE BEND, THE GREATER THE MOVEMENT WILL BE.
ALL WIRE ROPE GENERALLY HAVE THREE COMPONENTS:
- WIRES WHICH WILL FORM THE STRANDS, WHICH WILL FORM THE ROPES STRENGTHS.
- THE STRANDS, WHICH ARE HELICALLY WOUND AROUND THE CORE.
- THE CORE, WHICH WILL FORM A FOUNDATION FOR THE STRANDS
THE CORE OF A WIRE ROPE IS AN INDEPENDENT WIRE ROPE , SUCH AS IWRC (INDEPENDENT WIRE ROPE CORE), WHICH IS A WIRE ROPE ITSELF. THE CORE CAN ADD 10% TO UP TO 50% OF THE ROPES STRENGTH. CORES CAN ALSO BE OF A MATERIAL SUCH AS HEMP, OR POLYPROPYLENE.
THE GREATEST DIFFERENCE IN WIRE ROPE ARE TO BE FOUND IN THE NUMBER OF STRANDS, THE CONSTRUCTION OF THE STRANDS, THE SIZE OF THE CORE, AND THE LAY DIRECTION OF THE STRANDS VERSUS THE INNER CORE.
WIRE ROPE WIRES CAN BE MADE FROM A HIGH CARBON CONTENT STEEL. THE STEEL WIRES CAN ALSO BE OF VARIOUS GRADES. GRADES OF THE WIRE ROPE WILL DETERMINE THE BREAKING STRENGTH OF THE WIRE ROPE. MOST COMMON GRADES OF WIRE ROPE ARE IMPROVED PLOW STEEL (IPS), EXTRA IMPROVED PLOW STEEL (EIPS), AND EXTRA-EXTRA IMPROVED PLOW STEEL(XXIPS). (XIP HAVE 15% HIGHER MINIMUM BREAKING FORCE THAN IPS, XXIP HAS 10% HIGHER MINIMUM BREAKING FORCE THAN XIP ROPES) THE GRADE OR STRENGTH OF A WIRE ROPE IS IMPOSSIBLE TO VISUALLY DETERMINE, THE ONLY WAY TO VERIFY THIS INFORMATION IS TO OBTAIN CERTIFICATION FROM THE MILL. THIS WILL ALSO DETERMINE OR PROVE IF A WIRE ROPE IS DOMESTIC OR IMPORTED.
WIRE ROPE IS MANUFACTURED WITH A CORE MARKER, USUALLY A THIN IMPRINTED “TAPE”, WHICH WILL VERIFY THE MANUFACTURER AS WELL. BUT… ONCE A WIRE ROPE IS USED THE CORE MARKER WILL GENERALLY BREAK DOWN AND BE IMPOSSIBLE TO READ. THE WIRE ROPE MANUFACTURER ALSO PAINTS A STRAND OF THE WIRE ROPE WITH A COLORED GREASE TO VISUALLY VERIFY THE MAKER, ALL WIRE ROPE FABRICATORS HAVE THEIR OWN COLORED MARKING IDENTIFICATION. THIS COLORED GREASE WILL ALSO WEAR AWAY DURING REGULAR USE.
THE 6X19 CLASSIFICATION OF WIRE ROPE WILL INCLUDE THE STANDARD 6 STRAND, WITH ROUND STRAND ROPES WITH A 16 THROUGH 26 WIRES PER STRAND. THE 6X36 CLASSIFICATION OF WIRE ROPES INCLUDE STANDARD 6 STRAND, ROUND ROPE STRAND ROPES WITH 27 THROUGH 49 WIRES PER STRAND. ALTHOUGH THEIR OPERATING CHARACTERISTICS VARY, ALL HAVE THE SAME WEIGHT PER FOOT AND THE SAME MINIMUM BREAKING FORCE, SIZE FOR SIZE.
WHILE THE 6X19 ROPES GIVE PRIMARY EMPHASIS TO ABRASION RESISTANCE IN VARYING DEGREE, THE 6X36 ROPES ARE IMPORTANT FOR THEIR FATIGUE RESISTANCE. THE FATIGUE RESISTANCE IS MADE POSSIBLE BY THE GREATER NUMBER OF SMALL WIRES PER STRAND.
ALTHOUGH THERE ARE EXCEPTIONS FOR SPECIAL APPLICATIONS, THE CONSTRUCTIONS IN 6X36 CLASS ARE PRIMARILY DESIGNED TO BE THE MOST EFFICIENT FOR EACH ROPE DIAMETER. AS THE ROPE SIZE INCREASES, A LARGE NUMBER OF WIRES CAN BE USED TO ACHIEVE THE REQUIRED FATIGUE RESISTANCE AND STILL THOSE WIRES WILL BE LARGE ENOUGH TO OFFER ADEQUATE RESISTANCE TO ABRASION.
THE LAY OF THE ROPE AFFECTS ITS OPERATIONAL CHARACTERISTICS. REGULAR LAY IS MORE STABLE AND MORE RESISTANT TO CRUSHING THAN LANG LAY. WHILE LANG LAY IS MORE FATIGUE RESISTANT AND ABRASION RESISTANT, USE IS NORMALLY LIMITED TO SINGLE LAYER SPOOLING AND WHEN ROPE AND LOAD ARE RESTRAINED FROM ROTATION.
“LAY” IS THE DESCRIPTIVE MEANING OF THE WIRE AND STRAND POSITION IN THE ROPES. (FIRST TWO) THE THIRD MEANING IS A LENGTH MEASUREMENT USED IN MANUFACTURING AND INSPECTION.
TO DETERMINE THE LAY, USE THE DIRECTION THE STRANDS LAY IN THE ROPE, RIGHT OR LEFT. LOOK DOWN A ROPE, STRANDS OF A RIGHT LAY ROPE GO AWAY FROM YOU TO THE RIGHT. LEFT LAY IS THE OPPOSITE.
IN APPEARANCE, WIRES IN REGULAR LAY APPEAR TO RUN STRAIGHT DOWN THE LENGTH OF THE ROPE, AND IN LANG LAY, THEY APPEAR TO ANGLE ACROSS THE ROPE. IN REGULAR LAY, WIRES ARE LAID IN THE STRAND OPPOSITE THE DIRECTION THE STRANDS LAY IN THE ROPE. IN LANG LAY, THE WIRES ARE LAID THE SAME DIRECTION IN THE STRAND AS THE STRANDS LAY IN THE ROPE.
THE LENGTH ALONG THE ROPE THAT A STRAND MAKES ONE COMPLETE SPIRAL AROUND THE ROPES CORE. THIS IS A MEASUREMENT FREQUENTLY USED IN WIRE ROPE INSPECTION. STANDARDS AND REGULATIONS REQUIRE REMOVAL FROM SERVICE WHEN A CERTAIN NUMBER OF BROKEN WIRES PER THE ROPE LAY ARE DETECTED.
NO SINGLE ROPE CAN DO IT ALL, WHEN YOU NEED A ROPE WITH GREATER ABRASION RESISTANCE, ONE CHOICE IS A ROPE WITH FEWER (AND LARGER) OUTER WIRES TO REDUCE THE EFFECTS OF SURFACE WEAR. BUT THAT ALSO MEANS THE ROPE’S FATIGUE RESISTANCE WILL DECREASE. THIS IS WHY YOU WILL NEED TO CHOOSE YOUR WIRE ROPE LIKE YOU WOULD ANY OTHER MACHINE. VERY CAREFULLY, ALL CONSIDERATIONS FOR OPERATING CONDITIONS AND THE WIRE ROPE CHARACTERISTICS MUST BE ACCOUNTED FOR.
CONTACT YOUR SALES REPRESENTATIVE, OUR INSIDE SALES, OR LINK TO ONE OF OUR WIRE ROPE FABRICATORS. ORIGINAL EQUIPMENT MANUFACTURER (OEM) CAN ADVISE WHAT ROPES ARE FOR WHICH CRANES OR MACHINES
Additional Information : Wire Rope & Accessories
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