1、Corrugated Fiberboard Boxes 瓦楞纸板箱,Historical perspectiveCorrugated BoardProperties and TestsCorrugated BoxesCarrier RulesStacking and Compression,一. Historical perspective,1. Appearance of corrugated paper and the development First patents for making were recorded in England in 1856. First patents i
2、n US were granted to A.L.Jones in 1871 Unlined corrugated sheet-packing lamp chimneys and fragile objects. The first user double-lined corrugated boxes was a cereal manufacturer (obtained acceptance in 1903) Figures reversed from 20% to 80% between the world War I and II 2. The specialized produce S
3、heet plants buy combined board only printing and cutting. About 770 plants produce more than 17.3 billion worth in America3. Rules for constructing corrugated containers To enhance the quality Rule of UFC and NMFC,二. Corrugated Board,1. Construction : linerboard and mediumMaterial :heavy paper -cont
4、ainerboard Facings-kraft linerboard Medium-one-ply sheet, hardwood or recycled fiber,二. Corrugated Board,2 Four types combined board,b. Single Wall(Double Face) one mediumtwo liner boards,a. Single Faceone medium one liner board(for protective wrapping),二. Corrugated Board,c. Double Wall two mediums
5、three liner boards,d. Triple Wallthree mediumsfour liner boards,Direction: Machine Direction Cross Direction -flute direction,动画,二. Corrugated Board,3. FlutesProfile: arches with proper curve- the strongest way to span spaceFlutes as arches- resist bending and pressure, support weight, as cushion.Pr
6、oper curve: between U and V (Also has its advantages)Flutes also as a insulator to protect sudden temperature changes Vertical linerboard provides strength; protects from damage.,Several standard shapes (A,B,C,E,F) , Contrast: A-flute - the largest profile B-flute -smaller than A C-flute -between A
7、and B E-flute - smaller than B F-flute - micro-flute New flute-Macro-flute,二. Corrugated Board,Combined board -Different flute profiles combined in one boardone layer of medium might be A-flute while the other C-flute Manipulate the compression and cushioning strength, total thickness of the board.,
8、Standard flute configurations,*Not including facings;1foot = 0.3047999m“Take-up factor” is the length of medium per length of finished corrugated board,Described: the component of grammage or basis weight, from outside to insideeg. corrugated board “205/127C/161”-Outside liner = 205grams; Medium = 1
9、27 grams, formed to C-flute;Inside liner = 161grams,二. Corrugated Board,4 . Fiberboard Grades : Weight ; Thickness ; Material,Grammage: the mass in grams per square meter.Basis weight: the weight in pounds per 1,000 square feet ( abbreviated lb/MSF).,The most commonly used corrugating medium weights
10、,Meterial :Linerboard - natural kraft ;Solid bleached white kraft ; Mottled white ; Oyserboard Linerboard with a whiter surface provide better graphics. Recycled or secondary fiber -producing both two components Recycled board -smoother surface finish ;low CoF; excellent printing surface.,二. Corruga
11、ted Board,The most commonly used linerboard grades, based on Mullen burst test grading.,1 kg = 2.2046 b 1 meter = 3.28084 foot1 g/m2 = 0.205 b/MSF,A generation of newer linerboards has high-performance boards, meeting ECT rather than Mullen burst test and basis weight requirements. lighter grades of
12、 the high-performance boards to get satisfactory performance,二. Corrugated Board,5. Corrugating Adhesive,The corrugating machine forms the medium into a fluted pattern and bonds it to the linerboard facings , usually with a starch-based adhesive 1) A starch-based adhesive applied at about 10 to 14 g
13、rams per square meter. 2) Requirements : not tolerant high moisture and loses strength quickly. 3) When higher resistance is needed, starches can be modified or supplemented by the addition of various polymeric materials. 4) Weather-resistant adhesive would maintain box properties at a somewhat high
14、er level for a longer period. 5) Water-resistant adhesive would be required for those applications where the finished container will be in actual contact with water for periods of time, and the coating or waxed should be treated,二. Corrugated Board,6. Broad Manufacture Corrugating machine is made up
15、 of a set of stations that take the appropriate linerboards and mediums, shape the flutes, join fluted medium to linerboards.,Precondition medium with heat and steam Pretreated linerboards to the same temperature and moisture Brass fingers Flute tips adhesive,The single-facer of a corrugating machin
16、e is where the flutes are formed and bonded to the inside liner,二. Corrugated Board,Bridge -Draped in an overlapping wave pattern to the double-backer station Purpose-Isolating the two ends of the corrugating machine; balance; slow down,二. Corrugated Board,Manufacture: Adhesive - On the other side o
17、f the medium to glue outer linerboard. Final heating and cooling section - Between two long , flat belts. Trimming edges- Slit board to required width and length and stack Balanced construction- Outer and inner have identical grammage. Upgrading only one liner may gain performance. Unbalanced constr
18、uctions - more problems with board wrappage. Heavier liner is placed on the outside for better printing and on the inside for better compression strength.,三. Properties and Tests,Most board tests are described in methods provided by TAPPI.,Standard corrugated board burst and crush tests.,Mullen burs
19、t test (TAPPI T 810) Forcing a rubber diaphragm against the facing until it bursts,三. Properties and Tests,2. ECT (TAPPI T 811)A small specimen is placed between the platens of a compression tester and loaded until failure occurs. Values are a function of the stiffness contributed by the facings and
20、 the medium. ECT values have a direct relationship to the projected stacking strength. 3. Flat Crush Test (TAPPI T 808) Similar to the edge compression test except the specimen is compressed in the flat. The test provides a measure of flute rigidity. 4. Combined Weight of FacingsDescribes the combin
21、ed linerboard weight per 1,000 square feet of corrugated board 5. Thickness of Corrugated Board (TAPPI T 411)Reduced board thickness (caliper) is an excellent indicator of reduced compression strength; Caliper can be reduced by improper manufacture, excessive printing pressure, improper handling and
22、 storage,三. Properties and Tests,6. Gurley Porosity (TAPPI T 460 and T 536) Measures the time it takes for a given volume of air to pass through a paper. The lower the number, the more porous the paper. The porosity of paper is sometimes the culprit when problems occur at vacuum-cup transfer points.
23、 Flexural Stiffness (TAPPI T 820)Rrelated to box compression strength. Reduced stiffness is a good indicator of damage during fabrication. Water Take-up Tests (TAPPI T 441)The Cobb size test, measures the amount of water absorbed by the facing in a given time, used to measure water absorption for ma
24、terials specified to be used for hazardous product containers,三. Properties and Tests,9. Puncture Test (TAPPI T 803)Measures the energy required to puncture a board with a triangular pyramidal point affixed to a pendulum arm.Test the resistance and stiffness of triple wall corrugatedThe box makers s
25、tamp on triple wall containers calls for a puncture test 10. Pin Adhesion (TAPPI T 821) Pin adhesion quantifies the strength of the bond between the mediums flute tips and the linerboard facings. 11. Ply Separation (TAPPI T 812)Evaluates the boards resistance to ply separation when exposed to water.
26、 Coefficient of Friction (TAPPI T 815 and ASTM 04521). CoF can affect machinability and load stability. A stress/strain machine method will give both static and dynamic CoF values,四. Corrugated Boxes,1. Selecting the Correct Flute,use a carrier classification and C-flute as good starting points.,Com
27、parison of corrugated board characteristics,四. Corrugated Boxes,E- and F-flutes are not used in shipping containers but rather are replacements for thicker grades of solid paperboard. Can be considered if a folding carton design calls for boards thicker than 750(30 point). Also be used to replace pa
28、perboard for heavier or special protective primary packs as primary container while in distribution. Such as small tools, hardware, small appliances, and housewares,A-flute originally specified, not commonly use . almost 5 mm (1/4 in.) Occupies more space ,has significantly greater deflection before
29、 bearing a load when compressed. The thicker section give it the highest top-to-bottom compression strength. A-flute has the lowest flat crush resistance,B-flute is used where box stacking strength is not required. B-flutes has high flat crush strength when supporting heavy goods.,C-flute - 10% bett
30、er stacking strength than the same weights of B-flute,四. Corrugated Boxes,Relative flute flat crush values,四. Corrugated Boxes,2. Box Style Many standard box styles can be identified in three ways: by a descriptive name, by an acronym based on that name, or by an international code number. For examp
31、le, a Regular Slotted Container could also be referred to as an RSC or as #0201. There are many standard corrugated box styles: Slotted Boxes, Telescope Boxes, Folders, Rigid Boxes (Bliss Boxes), Self-Erecting Boxes and Interior Forms “Regular Slotted Container”(RSC or #0201) is the workhorse corrug
32、ated box style (Figure 4.10). All his flaps have the same length, and the two outer flaps (normally the lengthwise flaps) are one-half the containers width, so that they meet at the center of the box when folded. If the product requires a flat, even bottom surface, or the protection of two full laye
33、rs, a fill-in pad can be placed between the two inner flaps.,四. Corrugated Boxes,Figure 4.10 Parts of a regular slotted container (RSC) blank,四. Corrugated Boxes,3. Manufacturers jointA flat piece of corrugated fiberboard, which has been cut, slotted and scored, is called box blank. For some box sty
34、les, in order to make a box, the two ends of the box blank must be fastened together with tape, staples or glue. The place where these two ends meet is known as the manufacturers joint. Liquid adhesives are most often used to join the two surfaces. Often there is a glue tab, extending along one end
35、of the box blank. The tab can be joined to either the inside or the outside of the box. If there is no tab, the box must be joined using tape. Not all boxes have manufacturers joints; for example, the bliss box does not.,四. Corrugated Boxes,Bliss style container,Bliss-style box design variations,4.
36、Dimensioning Dimensions are given in the sequence of length, width and depth. Dimensions can be specified for either the inside or the outside of the box. Accurate inside dimensions must be determined to ensure the proper fit for the product being shipped or stored. At the same time, palletizing and
37、 distributing the boxes depends on the outside dimensions. The box manufacturer should be informed as to which,四. Corrugated Boxes,Top Loading,End Loading,五. Carrier Rules,1. ApplicationThe Uniform Freight Classification (UFC) and National Motor Freight Classification (NMFC) were established to cate
38、gorize articles for shipment via common carrier with respect to value, density, fragility, and potential for damage to other freight. The classifications specify the conditions under which specific articles can be shipped and at what rates. When shipping by rail, refer to UFC. When shipping by truck
39、, refer to NMFC. UFC rule 41 and NMFC item 222 are the most frequently used in describing corrugated packaging. There are four basic steps for determining authorized packaging: 1. Fully identify the product. 2. Select the proper governing classification.3. Use the “Index to Articles“ to find the app
40、licable item number. 4. Consult the proper article to find the required packaging.,五. Carrier Rules,Failure to comply with regulations can subject the shipper to penalties such as higher freight rates, refusal of acceptance by the carrier, or nonpayment of damage claims. 2. Summary of Rules for Corr
41、ugated Box Construction Carrier rules for corrugated box construction can be summarized as follows: Specified boards (using either Mullen burst test or ECT values) shall be used for a given product weight, providing the box does not exceed a specified dimensional limit. The dimensional size limit fo
42、r a box is determined by adding an outside length, width, and depth. Table 4.6 summarizes the construction requirements for corrugated boxes. The rules also require that a box manufacturers certificate (BMC) on the bottom of the container ( Figure 4.11).,五. Carrier Rules,Figure 4.11 Box manufacturer
43、s certificates using burst test and ECT values,五. Carrier Rules,Table 4.6 Summary of carrier rules for corrugated boxes,五. Carrier Rules,五. Carrier Rules,* Mullen(Part A) and ECT(Part B) are presented side-by-side,but there is no correlation between the values,六. Stacking and Compression,1. McKee fo
44、rmula Stacking strength is defined as the maximum compressive load (pounds or kilograms) that a container can bear over a given length of time, under given environmental/ distribution conditions without failing. The ability to carry a top load is affected by the structure of the container and the en
45、vironment it encounters, and the ability of the inner (primary) packages and the dividers, corner posts, etc. to sustain the load. The simplest and most common corrugated transport packages are regular slotted containers (RSCs, Box Style 0201) in which the corrugation direction is typically vertical
46、-parallel to top- bottom stacking forces. Compression strength of regular slotted containers is a function of: Perimeter of the box (two times length plus two times width) Edge crush test of the combined board Bending resistance of the combined board Aspect ratio (L:W) and other factors,六. Stacking
47、and Compression,When we know the above variables, we can estimate the compression strength through an equation known as the McKee formula. BCT=2.028 (ECT)0.746 (DxDy)0.254)1/2 BP0.492 (4.1),Where:BCT = RSC top-to-bottom box compression strength, kN/m2(lbf/in.2 or p.s.i) ECT = edge crush test, kN/m (
48、lbf/in.)Dx,Dy = flexural stiffnesses of combined board in the machine direction and cross direction, kN/m(lbf/in.) BP = inside box perimeter, m (in.),六. Stacking and Compression,The McKee formula can only be applied to RSCs, and only those with a perimeter-to-depth ratio no greater than 7:1. McKee a
49、lso created a simpler formula based on caliper of the combined board instead of bending stiffness: BCT=5.87ECT (TBP)1/2 (4.2)Where: T = caliper of combined board, m (in.)Solving for ECT, the simplified McKee formula is: ECT = BCT /5.87 (T BP)1/2 (4.3）,六. Stacking and Compression,The ability of a container to perform in distribution is significantly impacted by the conditions it encounters throughout the cycle. If the original box compression strength is known, we can factor it by generally accepted multipliers to arrive at an estimated maximum safe stacking strength (Table 4.7),
