Impact resistance of fiberboard shipping containers

Transcription

1 T 801 m-94 SUGGESTED METHOD 1944 OFFICIAL STANDARD 1971 OFFICIAL TEST METHOD 1983 REVISED TAPPI The infrmatin and data cntained in this dcument were prepared by a technical cmmittee f the Assciatin. The cmmittee and the Assciatin assume n liability r respnsibility in cnnectin with the use f such infrmatin r data, including but nt limited t any liability r respnsibility under patent, cpyright, r trade secret laws. The user is respnsible fr determining that this dcument is the mst recent editin published. Impact resistance f fiberbard shipping cntainers 1. Scpe 1.1 The purpse f this methd is t prvide cmparative qualitive infrmatin n the impact behavir f cntainers r their cntents r bth. The data btained are nt meant t be exact and quantitative because f the test variables invlved and the diverse nature and characteristics f the endpints. The methd describes three prcedures fr making inclined impact tests n laded fiberbard shipping cntainers as fllws Prcedure A, t determine the ability f a cntainer t withstand impact stresses Prcedure B, t determine the ability f a cntainer r interir packing, r bth, t prvide prtectin f the cntents when subjected t impact stresses Prcedure C, t simulate the types f shck pulses experienced by lading in railcar switching, with the use f a rigid bulkhead n the frnt edge f the dlly, and prgramming techniques. Prcedure C may als be used t simulate cmpressive frces experienced by lading during railcar switching with the use f backlading. 1.2 The prcedures prescribed in this methd are particularly suitable fr testing large cntainers r laded cntainers, having a grss mass greater than 45 kg (100 lb). 2. Significance 2.1 Each prcedure is primarily useful within a labratry, in cmparing different designs f cntainers f the same size and carrying the same lad. 2.2 The inclined plane impact test has been fund useful in labratry simulatin f shcks such as might be encuntered in handling and transprtatin. 3. Apparatus 3.1 Inclined plane impact tester (Figs. 1 and 2), cnsisting f a tw-rail track inclined 10±1 frm the hrizntal, a backstp affixed at exactly 90 t the track and a fur-wheel dlly r rlling platfrm (1). Fig. 1. Incline impact test apparatus fr Prcedures A and B. Apprved by the Fiberbard Shipping Cntainer Testing Cmmittee f the Crrugated Cntainers Divisin TAPPI

2 T 801 m-94 Impact resistance f fiberbard shipping cntainers / 2 Fig. 2. Incline impact test apparatus fr Prcedure C The track. The length f the track may vary depending upn space limitatins and the user's needs. Impact velcity varies with the square rt f the length f the run because the incline angle is fixed. The incline is prvided with a manual r (preferably) a mtr-driven chain r cable fr raising the dlly and a device fr releasing the dlly at predetermined distances up the incline. The incline is graduated in cnvenient increments, such as 25 mm (1 in.). The track must be straight, free f bumps r bstructins, and must be kept clean The backstp The backstp shall be cnstructed slidly and braced r ballasted t prevent mvement when impacted. The track assembly and the backstp shall be firmly blted t the flr s that neither prtin has any significant mtin relative t the ther prtin A metal clad backstp is preferred; hwever, if it is faced with wd, Grup 4 wds as established by the U.S. Frest Prducts Labratry (2) (beech, birch, hackberry, hard maple, hickry, ak, pecan, rck elm, r white ash) must be used The surface r facing f the backstp shuld be free f prjectins r irregularities such as blts, nail heads, guges, abrasins, warping, buckling, r splits, which may affect the test results The backstp shall be f sufficient size t permit full cntact with the cntainer being tested The backstp may, if desired, be equipped s that remvable hazards, such as bards r timbers, may be added fr special tests The dlly The dlly wheels must rll freely and straight n the track and be smth and well lubricated The surface f the dlly flr is made frm renewable Grup 4 wds r Grup 4 plywd, as specified in 3.1.2, r may (preferably) have a steel flr, fr greater durability and ease in maintaining a surface free f irregularities The dlly shuld be f sufficient size t fully supprt the cntainer being tested Dlly bulkhead (Fig. 2) (used fr Prcedure C nly). Dlly shall be fitted with a bulkhead at a 90 angle t the dlly tp surface. Bulkhead shall be s fitted that upn release the bulkhead impacts first n the prgramming material, r the bulkhead and dlly impact at the same time. The bulkhead shall be securely attached and shall be a rigid structure Prgramming material (used fr Prcedure C nly) is required t shape and cntrl the pulse seen by the specimen. This material may be fastened t the backstp r the bulkhead and may be any material that gives a repeatable, cntrllable test, such as package cushining material r special prgrammers Impact recrder (used fr Prcedure C nly). 4. Calibratin 4.1 Fully calibrate the impact test apparatus t btain cmplete data n the velcity at pint f impact fr suitable increments ver the lengths f travel t be used. Prepare a chart r graph frm these values, fr use in selecting the height f the release pint (r length f travel) fr any desired velcity at impact. 4.2 Perfrm the calibratin n the empty dlly, by means f an electric timing device which measures the velcity f the dlly immediately befre its impact against the backstp. The velcity shuld be determined t within 0.01 m/s (0.03 ft/s).

3 3 / Impact resistance f fiberbard shipping cntainers T 801 m-94 NOTE 1: If such a timing device is nt used, calculate the average velcity frm the knwn length f rll and the elapsed time. The velcity at impact may be taken as twice the average velcity, althugh the effects f frictin will tend t make the actual impact velcity slightly lwer. 5. Test specimens 5.1 Select at least three, but preferably five, cntainers as nearly as pssible typical f the lt r style r cnstructin t be evaluated. 5.2 Pack the cntainer, clse, strap, r seal in the same manner as in actual shipment When the ability f the cntainer itself t withstand impact is t be evaluated (Prcedure A), a dummy lad, simulating the actual cntents in mass, shape, size, and resilience, may be used; hwever, where pssible, the use f the actual prduct is highly recmmended When the prtective ability f the package (cntainer plus interir packing) is t be evaluated (Prcedure B), pack it with the actual prduct fr which the package is designed. NOTE 2: A suitable artificial lad shuld be used as a substitute fr dangerus materials When fllwing Prcedure C, the apprpriate cntents under r shuld be used. 5.3 Cnditin and test the specimens, whenever pssible, in an atmsphere in accrdance with TAPPI T 402 Standard Cnditining and Testing Atmspheres fr Paper, Bard, Pulp Handsheets and Related Prducts. If this is nt pssible, nte in the reprt the cnditins f temperature and percent relative humidity under which the specimens were cnditined and the test was cnducted. Make all cmparisns under the same cnditins Alternatively, the cntainers may be cnditined prir t the incline impact test by ther physical tests r by ther cnditins f expsure, which may simulate anticipated service cnditins. 5.4 Identify the faces, edges, and crners f the cntainer as fllws; as the viewer faces ne end f the fiberbard cntainer, with the manufacture's jint n the near right, the tp f the cntainer is designated as 1, the right side as 2, the bttm as 3, the left side as 4, the near end as 5, and the far end as 6. Each edge is identified by the numbers f the tw faces which frm that edge; fr example, 1-2 identifies the edge where the tp and right side meet, and 2-5 is the edge frmed by the right side and the near end (this edge will have the numbers f the manufacturer's jint). Each crner is identified by the numbers f the three faces which meet t frm that crner; fr example, identifies the crner where the tp, the right side, and the far end meet (Fig. 3). Fig. 3. Identificatin f faces, edges, and crners. 5.5 In the case f ther than rectangular cntainers, any cnvenient and unambiguus system f identificatin may be used in the reprt. 6. Prcedures 6.1 Prcedure A: t determine the ability f a cntainer t withstand impact stresses. Place the cntainer t be tested n the dlly with the face r edge which is t receive the impact lcated with (a) cincident with the frward end f the dlly, r (b) prjecting slightly beynd the frward end f the dlly s that the cntainer under test strikes the

4 T 801 m-94 Impact resistance f fiberbard shipping cntainers / 4 backstp first. Bring the dlly t the predetermined psitin n the incline and release it. Recrd the velcity at impact. If it is desired t cncentrate the impact at any particular psitin n the cntainer, attach a timber apprximately 100 mm x 100 mm (4 in. x 4 in.) t the backstp in the desired psitin befre the test. N part f the timber is t be struck by the dlly. The psitin f the cntainer n the dlly and the sequence in which the faces and edges are subjected t impacts may be at the ptin f the peratr and will depend upn the bjective f the tests. Repeat the impacts until failure f the cntainer ccurs. Depending upn the purpse f the test, failure is cnsidered t have ccurred when (a) the cntents have spilled, r (b) any part f the cntents may be remved frm the cntainer withut damaging it further, r (c) sme predetermined type r types f damage have ccurred t the cntainer. NOTE 3: Under this prcedure, the cntainer is being tested rather than the cntents. If the specimen fails thrugh failure f the cntents (leakage f liquids r ther evidence), discntinue the test and d nt use the results. It may, hwever, be useful r desirable t nte such ccurrences. 6.2 Prcedure B: t determine the ability f a cntainer r interir packing t prvide prtectin t the cntents. This test is cnducted as described in 6.1 until a predetermined number f impacts f prescribed intensity have been applied, whereupn the cntainer is pened fr inspectin, unless previus evidence f failure is already apparent. NOTE 4: The distance frm the backstp at which the dlly and cntainer are released will depend upn the purpse f the test. The test may be started at any suitable distance, and succeeding tests run frm (a) the same distances, r (b) distances which are increased by equal increments fr each impact. 6.3 Prcedure C: t determine the perfrmance f shipping unit in simulated rail switching impact. Cnduct this test by placing the specimen(s) n the dlly and against the bulkhead. Use impact velcity and prgramming material t prduce the pulse(s) required, with simulated backlad in place. The backlad may be a duplicate specimen, similar t the test package r weights, t simulate the ther lading in the railcar. When required, the bulkhead shall be mnitred adjacent t test specimen(s) and deceleratin level and time duratin recrded. 7. Reprt Include the fllwing in the reprt: 7.1 The dimensins f the cntainer under test; its cmplete structural specificatins, kind f fiberbard, descriptin and specificatins fr blcking and cushining; methd f clsing and strapping, if any; and the net and grss weights. 7.2 Descriptin f the cntents f the cntainer under test. 7.3 A detailed recrd f the test n each set f specimens. Fr Prcedure A, include the average number f impacts t failure, the rientatin and lcatin f the specimens n the dlly, the velcity at each impact, and the damage t the cntainer and cntents (tgether with any ther bservatin which may assist in crrectly interpreting the results r aid in imprving the design f the cntainer r the methd f packing, blcking, r cushining). 7.4 The methd f cnditining the cntainers; the misture cntent f the fiberbard; and the results f any supplementary tests f the materials frm which the cntainer is made. 7.5 A recrd f the calibratin f the impact test apparatus. 7.6 An accunt as t the use f the ptinal timber hazard. 8. Precisin 8.1 Values f repeatability and reprducibility cannt practically be determined fr this methd. In general, any precisin data will be s equipment and package specific as t be f limited value. 8.2 This methd prvides cmparative qualitative infrmatin n impact behavir and is nt cnsidered suitable fr directly cmparing results between labratries because f variatins in design and cnstructin f the apparatus and difficulties in specifying and cntrlling backstp rigidity. 9. Additinal Infrmatin 9.1 Effective date f issue: January 26, See NSTA Pre-shipment Test Prcedures, Prject 1A fr a specific applicatin f TAPPI T 801.

5 5 / Impact resistance f fiberbard shipping cntainers T 801 m-94 References 1. A detailed descriptin f this apparatus with cnstructin drawings appears in General Infrmatin Series 511, Damage Preventin Sectin, Assciatin f American Railrads, 59E Van Buren Street, Chicag, IL U.S. Department f Agriculture, Frest Prducts Labratry, Wd Crate Design Manual, Agriculture Handbk 252, Washingtn, D.C. 3. Related methd: ASTM D Yur cmments and suggestins n this prcedure are earnestly requested and shuld be sent t the TAPPI Technical Divisins Administratr.