7 Tensile StrengthTensile strength is characteristic of a type of material and the way it has been processedPP N/mm2PET N/mm2PET N/mm2Apex STEEL N/mm2Magnus STEEL N/mm2Composite Strapping n/a ( No homogenous Crossection)
8 Break strength is characteristic of a specific strap. It is the product of cross-sectional area and tensile strengthPET 19mm x 1.27mm x 450N/mm2 = ~ 11,000NMagnus Steel Strap 19mmx0.63mm= 19mm x 0.63mm x 1.050N/mm2 = ~ 12,500N
9 Joint Strengts The joint strength determines the loop strength! Examples for PET Strapping:Pneumatic hand tools to 60% (Stick to min for variations in air pressure and flow or PET sheet material.)Battery Charged Tool to 75% (Depending on strap type sheet single extruded)Machines 80 to 90 % single extruded
10 Joint Strength of Composite Strapping JOINT EFFICIENCY of POLYESTER CORDED COMPOSITE STRAPS: 80 – 90 %
11 Joint Strength of Steel Strapping at Different Joint Types
13 Retained TensionRetained tension is the strap tension that remains over timeApplied tension is the tension that is initially applied to a strapTension decay is the tension that is lost over timeRetained tension :Steel 90 to 95%PET 65 to 75%PP 25 to 35%Composite Strap 80 to 90%The size of the strap does not affect the RT.
15 Working RangeWorking range of PET and steel strap are about 50% of their break strengths.Working range of PP is about 35% of its break strength.Working range elongation is the main reason why PET is tougher than steel. Steel % PET % PP- Special 6%Composite Strapping 4 – 6%
18 Impact resistanceImpact resistance is measured by work (energy necessary) to break/deform the strap.Calculation:Working range (%) x Joint strength (N) x Working range elongation (%)Comparison between Steel Strap 32 x 0,8 applied with a double notch seal, and a PET 19 x1,27mm PET Strap with battery tool :Apex 31,75 x 0,8 mm BS is Nx 70% JS = N50% x x 0,3 = NmmPET 19,05 x 1,27 BS is N x 75% JS = N50% x x 4 = NmmSo the PET Strap and also COMPOSITE STRAPs in this case is half the strength but 7 ( Seven) times tougher!!!!
21 Factors affecting strap choice Function or purpose of the strapPackage characteristicsShipping or handling considerationsStrapping may perform the following functions:package reinforcement, carton closure, securement, unitization, baling, bundling, bracing, paletization, compression retention and pilferage reduction.Package characteristics that influence strap selection are: weight, stability, rigidity, integrity and sharpness of the edges (sharp edges may demand heavier strapping or corner protection).Shipping considerations that affect the choice of strapping include: how far the package is shipped; how it’s handled by both the shipper and receiver; and where and how it’s stored.
22 EQUIPMENT BY PACKAGE TYPES Shape:Rectangular Normal hand-tools / MachinesRound Push type tools / (Machines)Weight:How much mass has to be held together?Weight StrapsPackage stability:Is the product stabile by itself, is the stacking stabile?Strapping to hold pack on pallet, or to hold pack together?What happens when a strap breaks?CostsSafetyProduct edges:Does strap damage product? Corner-protectionDoes product damage strap?Need to distribute more tension?
23 Transport (Intern/Extern) You may ask yourself the following questions:How is the pack lifted / handled?Forklift, magnetic overhead crane, roller-conveyor, etc.How long is the pack in storage?Shrinking, corrosion.Conditions of storage?Moisture, dust, sunlight, heat, ice, etc.Way of storage?Stacked, in racksWay of transport?Truck, train (shunting), ship, airfreight.Distance of transport?Domestic or Export, the more transport actions, the higher the risk .
24 At the end customer How does the end customer handle the package? Forklift truck, roller conveyor, magnetic crane, etc.How / when does he take the packaging apart?Any hazards, complications?Is there intermediate storage?Many more handlings, very long storage times.Does the pack get resold?Needs to be broken down to smaller units.Try to think further …..
25 Types of Steel Strapping Apexis a cold-rolled, low carbon steel strapping. It isused for light and medium duty loads that needhigh strength and high retained tension but are not subject to impacts or shock.Magnussteel strapping is made from higher-carbon, cold-rolled, heat treated steel. It is used on heavy/very heavy loads that require high strength and are subject to impacts andshock during transit and handling.USLMsteel strapping is made from higher-carbon, cold-rolled, heat treated steel. It is used on very heavy/extreme loads.
27 Why waffled strap Advantages: Disadvantages at heavy waffling : A thicker strap with a lower Gram / Meter (Cheaper)Stiffer, good feeding through chutesDisadvantages at heavy waffling :Longer weldtime, or weaker weld.Less meterage per Kg.Tension-wheel grips in “air”A smaller smooth strap can replace a wider waffled strap.
31 NUMBER of STRAPS REQUIRED CALCULATION Minimum Number of Straps=(Load Weight x G Force x 1,5 )/System Strength1,5 : Safety FactorSafety Factor can be varied according the transportation mode and also type of the product.System Strength of Composite Strapping = 1,6 x Nominal Break Strength
32 Çember Miktarı Hesaplama Örneği : Palet Weight : 3000 kgStrap Used : CS32ESTR Composite StrapBreak Strength of the Strap : 1600 kgSystem Strength of the Strap : 2560 kgSafety factor : 1,5Minimum # of Straps should be on the Pallet = 3000 x 1,5 / 2560= 1,76Two ( 2 ) Straps
33 Steel Strapping vs PET / Composite Strapping Steel Strapping has :AdvantagesDisadvantagesHigh Corner StrentgthLow ElasticityHigh Breaking StrengthLow Elongation RecoveryTensionable with hand, pneumatic or fully automatic machinesLow Shock Absorbency ( Impact )High Static System Strength if closed properlyLow3 Dynamic System StrengthCan be tensioned manually or sealed with battery tensionerDangerous to users , Damage to productsAlso fully automatic possibleExpensive than PET / Composite strapping