Package cushioning is used to protect items during shipment. Vibration and impact shock during shipment and loading/unloading are controlled by cushioning to reduce the chance of product damage.
Cushioning is usually inside a shipping container such as a corrugated box. It is designed to absorb shock by crushing and deforming, and to dampen vibration, rather than transmitting the shock and vibration to the protected item. Depending on the specific situation, package cushioning is often between 50 and 75mm (2 and 3in) thick.
Internal packaging materials are also used for functions other than cushioning, such as to immobilize the products in the box and lock them in place, or to fill a void.
End caps and corner blocksMolded pulp cushioningThermoformed end caps for a hard driveCoiled cable mount for heavy duty reusable containers
Loose fill
Some cushion products are flowable and are packed loosely around the items in the box. The box is closed to tighten the pack. This includes expanded polystyrene foam pieces (foam peanuts), similar pieces made of starch-based foams, and common popcorn. The amount of loose fill material required and the transmitted shock levels vary with the specific type of material.[2]
Paper can be manually or mechanically wadded up and used as a cushioning material. Heavier grades of paper provide more weight-bearing ability than old newspapers. Creped cellulose wadding is also available. Movers often wrap objects with several layers of kraft paper or embossed pulp before putting them into boxes.
Multi-layer or cut-and-folded shapes of corrugated board can be used as cushions.[3] These structures are designed to crush and deform under shock stress and provide some degree of cushioning. Paperboardcomposite honeycomb structures are also used for cushioning.[4]
Several types of polymeric foams are used for cushioning, the most common being expanded polystyrene, polypropylene, polyethylene, and polyurethane. These can be molded engineered shapes or sheets which are cut and glued into cushion structures.[5] Convoluted (or finger) foams are sometimes used.[6] Some degradable foams are also available.[7] Foam-in-place is another method of using polyurethane foams. These fill the box, fully encapsulating the product to immobilize it. It is also used to form engineered structures.
Molded pulp
Pulp can be molded into shapes suitable for cushioning and for immobilizing products in a package. Molded pulp is made from recycled newsprint and is recyclable.
Inflated products
Bubble wrap consists of sheets of plastic film with enclosed “bubbles” of air. These sheets can be layered or wrapped around items to be shipped. A variety of engineered inflatable air cushions are also available. Note that inflated air pillows used for void-fill are not suited for cushioning.
Other
Several other types of cushioning are available including suspension cushions, biofoams, thermoformed end caps,[8][9]viscoelastic materials,[10] and various types of shock mounts.
Design for shock protection
Equipment for a drop test of cushioned package to measure the transmitted shock
Proper performance of cushioning is dependent on its proper design and use. It is often best to use a trained packaging engineer, reputable vendor, consultant, or independent laboratory. An engineer needs to know the severity of shock (drop height, etc.) to protect against. This can be based on an existing specification, published industry standards and publications, field studies, etc.
Knowledge of the product to be packaged is critical. Field experience may indicate the types of damage previously experienced. Laboratory analysis can help quantify the fragility[11] of the item, often reported in g's. Engineering judgment can also be an excellent starting point. Sometimes a product can be made more rugged or can be supported to make it less susceptible to breakage.
The amount of shock transmitted by a particular cushioning material is largely dependent on the thickness of the cushion, the drop height, and the load-bearing area of the cushion (static loading). A cushion must deform under shock for it to function. If a product is on a large load-bearing area, the cushion may not deform and will not cushion the shock. If the load-bearing area is too small, the product may “bottom out” during a shock; the shock is not cushioned. Engineers use “cushion curves” to choose the best thickness and load-bearing area for a cushioning material. Often two to three inches (50 – 75mm) of cushioning are needed to protect fragile items.
Computer simulations and finite element analysis are also being used. Some correlations to laboratory drop tests have been successful.[12]
Cushion design requires care to prevent shock amplification caused by the cushioned shock pulse duration being close to the natural frequency of the cushioned item.[13]
Design for vibration protection
The process for vibration protection (or isolation) involves similar considerations as that for shock. Cushions can be thought of as performing like springs. Depending on cushion thickness and load-bearing area and on the forcing vibration frequency, the cushion may 1) not have any influence on input vibration, 2) amplify the input vibration at resonance, or 3) isolate the product from the vibration. Proper design is critical for cushion performance.
Evaluation of finished package
Verification and validation of prototype designs are required. The design of a package and its cushioning is often an iterative process involving several designs, evaluations, redesigns, etc. Several (ASTM, ISTA, and others) published package testing protocols are available to evaluate the performance of a proposed package. Field performance should be monitored for feedback into the design process.
ASTM Standards
D1596 Standard Test Method for Dynamic Shock Cushioning Characteristics of Packaging Material
D2221 Standard Test Method for Creep Properties of Package Cushioning Materials
D3332 Standard Test Methods for Mechanical-Shock Fragility of Products, Using Shock Machines
D3580 Standard Test Methods for Vibration (Vertical Linear Motion) Test of Products
D4168 Standard Test Methods for Transmitted Shock Characteristics of Foam-in-Place Cushioning Materials
D4169 Standard Practice for Performance Testing of Shipping Containers and Systems
D6198 Standard Guide for Transport Packaging Design
D6537 Standard Practice for Instrumented Package Shock Testing For Determination of Package Performance
and others
See also
Betagel, utilizes gel and silicone to absorb violent shocks
↑ Singh, S. P.; Chonhenchob and Burges (1994). "Comparison of Various Loose Fill Cushioning Materials Based on Protective and Environmental Performance". Packaging Technology and Science. 7 (5): 229–241. doi:10.1002/pts.2770070504.
↑ US 5515976,Moren, Michael S.; Schindler, Fred& Loga, Randall K.,"Packaging for fragile articles within container",published 1996-05-14, assigned to Plastofilm Inc.and Robert Stephens, VanAmburg Packaging Inc.
↑ Burgess, G (March 2000). "Extensnion and Evaluation of fatigue Model for Product Shock Fragility Used in Package Design". J. Testing and Evaluation. 28 (2): 116–120. doi:10.1520/JTE12084J.
Yam, K. L., "Encyclopedia of Packaging Technology", John Wiley & Sons, 2009, ISBN978-0-470-08704-6
Singh, J., Ignatova, L., Olsen, E. and Singh, P., "Evaluation of the Stress-Energy Methodology to Predict Transmitted Shock through Expanded Foam Cushions", ASTM Journal of Testing and Evaluation, Volume 38, Issue 6, November 2010
Corrugated fiberboard, corrugated cardboard, or corrugated is a type of packaging material consisting of a fluted corrugated sheet and one or two flat linerboards. It is made on "flute lamination machines" or "corrugators" and is used for making corrugated boxes. The corrugated medium sheet and the linerboard(s) are made of kraft containerboard, a paperboard material usually over 0.25 millimetres (0.01 in) thick.
In mechanics and physics, shock is a sudden acceleration caused, for example, by impact, drop, kick, earthquake, or explosion. Shock is a transient physical excitation.
Packaging is the science, art and technology of enclosing or protecting products for distribution, storage, sale, and use. Packaging also refers to the process of designing, evaluating, and producing packages. Packaging can be described as a coordinated system of preparing goods for transport, warehousing, logistics, sale, and end use. Packaging contains, protects, preserves, transports, informs, and sells. In many countries it is fully integrated into government, business, institutional, industrial, and for personal use.
In mechanics, an impact is when two bodies collide. During this collision, both bodies decelerate. The deceleration causes a high force or shock, applied over a short time period. A high force, over a short duration, usually causes more damage to both bodies than a lower force applied over a proportionally longer duration.
Vibration isolation is the prevention of transmission of vibration from one component of a system to others parts of the same system, as in buildings or mechanical systems. Vibration is undesirable in many domains, primarily engineered systems and habitable spaces, and methods have been developed to prevent the transfer of vibration to such systems. Vibrations propagate via mechanical waves and certain mechanical linkages conduct vibrations more efficiently than others. Passive vibration isolation makes use of materials and mechanical linkages that absorb and damp these mechanical waves. Active vibration isolation involves sensors and actuators that produce disruptive interference that cancels-out incoming vibration.
Electronic packaging is the design and production of enclosures for electronic devices ranging from individual semiconductor devices up to complete systems such as a mainframe computer. Packaging of an electronic system must consider protection from mechanical damage, cooling, radio frequency noise emission and electrostatic discharge. Product safety standards may dictate particular features of a consumer product, for example, external case temperature or grounding of exposed metal parts. Prototypes and industrial equipment made in small quantities may use standardized commercially available enclosures such as card cages or prefabricated boxes. Mass-market consumer devices may have highly specialized packaging to increase consumer appeal. Electronic packaging is a major discipline within the field of mechanical engineering.
Plastic lumber is a plastic form of lumber made of virgin or recycled plastic. It is mostly made of plastic and binders such as fiberglass or rebar; not to be confused with wood-plastic composite lumber. Widely employed in outdoor decking, it is also used for molding and trim and garden furniture such as park benches. Resistant to cracking and splitting when appropriately installed, plastic lumber can be molded with or without simulated wood grain details. Even with a wood grain design, plastic lumber is still easy to distinguish visually from natural timber: the grains are the same uniform color as the rest of the material.
Molded pulp or molded fiber is a packaging material, that is typically made from recycled paperboard and/or newsprint. It is used for protective packaging or for food service trays and beverage carriers. Other typical uses are end caps, trays, plates, bowls and clamshell containers.
A shock mount or isolation mount is a mechanical fastener that connects two parts elastically to provide shock and vibration isolation.
A bulk box, also known as a bulk bin, skid box, pallet box, bin box, gaylord, or octabin, is a pallet-size box used for storage and shipping of bulk or packaged goods. Bulk boxes can be designed to hold many different types of items such as plastic pellets, watermelons, electronic components, and even liquids; some bulk boxes are stackable.
Insulated shipping containers are a type of packaging used to ship temperature sensitive products such as foods, pharmaceuticals, organs, blood, biologic materials, vaccines and chemicals. They are used as part of a cold chain to help maintain product freshness and efficacy. The term can also refer to insulated intermodal containers or insulated swap bodies.
The term unit load refers to the size of an assemblage into which a number of individual items are combined for ease of storage and handling, for example a pallet load represents a unit load which can be moved easily with a pallet jack or forklift truck, or a container load represents a unit for shipping purposes. A unit load can be packed tightly into a warehouse rack, intermodal container, truck or boxcars, yet can be easily broken apart at a distribution point, usually a distribution center, wholesaler, or retail store for sale to consumers or for use.
A padded envelope, also known as a padded or cushioned mailer, or jiffy bag in the United Kingdom, is an envelope incorporating protective padding to protect items during shipping. The padding is usually thick paper, bubble wrap, or foam.
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Corrugated box design is the process of matching design factors for corrugated fiberboard or corrugated plastic boxes with the functional physical, processing and end-use requirements. Packaging engineers work to meet the performance requirements of a box while controlling total costs throughout the system. Corrugated boxes are shipping containers used for transport packaging and have important functional and economic considerations.
Package testing or packaging testing involves the measurement of a characteristic or property involved with packaging. This includes packaging materials, packaging components, primary packages, shipping containers, and unit loads, as well as the associated processes.
A shock data logger or vibration data logger is a measurement instrument that is capable of autonomously recording shocks or vibrations over a defined period of time. Digital data is usually in the form of acceleration and time. The shock and vibration data can be retrieved, viewed and evaluated after it has been recorded.
A shock detector, shock indicator, or impact monitor is a device which indicates whether a physical shock or impact has occurred. These usually have a binary output (go/no-go) and are sometimes called shock overload devices. Shock detectors can be used on shipments of fragile valuable items to indicate whether a potentially damaging drop or impact may have occurred. They are also used in sports helmets to help estimate if a dangerous impact may have occurred.
Overpackaging is the use of excess packaging. The Institute of Packaging Professionals defines overpackaging as “a condition where the methods and materials used to package an item exceed the requirements for adequate containment, protection, transport, and sale”
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