Packaging Line Integration for Input & Product Flow

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Karen Houston
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1 Packaging Line Integration for Input & Product Flow Introduction Integration as it relates to the packaging process is defined as the mechanical, pneumatic, hydraulic and/or electrical method of physically connecting machinery and input handling systems to ensure a smooth harmonized throughput operation. It should not be confused with automation, and control. Usually control or automation cannot solve or correct poor or faulty integration. Control is defined as the authority or ability to regulate, direct, or dominate a situation or series of events. For any packaging line, whether manual, semi-automatic or automatic, control is critical. Automation is a technique of making industrial machinery, a process, or a system operate in an independent or self-controlling manner. This is the generic definition of automation. With regard to packaging, this definition should be adjusted to reflect the objectives of packaging as subsequently stated. Automation is controlling the packaging line by using the optimum technique to cause the process to operate at a steady state rate in a self-controlling manner. Note these definitions say nothing about eliminating labor or guaranteeing profitability, but they both imply that automation will optimize labor and give the potential of profitability. As a minimum, integration considers the following factors: 1. Design and installation of Conveyor Systems 2. Design and installation of Guide Rails and Handling Control Components 3. Speeds, feeds, dynamics and loads for Interconnecting Machinery 4. Compatibility of Interconnecting Machinery 5. Integrating Manual Operations With Automatic Machinery 6. Line Shafting Machinery - Mechanically and/or Electronically In this brief paper we will be quickly looking at integration from the standpoint of this six factors. The analysis of the total packaging process requirement will identify all the machines that need to be integrated into the operation of a given production process. Typical machinery might included: depalletizers, uncasers, unscramblers, combiners air cleaners, rinsers, washers fillers - gravity, pressure, vacuum, volumetric, net weight, diaphragm, etc. warmers, coolers, pasteurizers, cookers, ovens. cappers - screw, plug, insert, crown, snap on, etc.

2 labelers - cold glue, hot glue, pressure sensitive, thermage, silk screen, print & apply, etc. inspections, checkweighing, quality control case packers, palletizers, divergers case conveyors, merges, elevators, etc. packaging line conveyors, collators, dividers, buffers robots - coordinate, scara, articulating, beam, gantry, etc. AGVs, pallet conveyors, stretch wrappers transfer to warehouse conveyors racking, storage and retrieval There are many other components, which perform special functions as required: a) quality inspection, vision, dud detector, no cap, low fill/high fill, etc. b) ink-jet coders, laser coding, RFID, bar coding/reading, etc. for tracking. c) heat tunnels d) soft reject stations, hard reject stations e) in-process storage (buffers) areas. f) collators, orienters, combiners, dividers, turners, etc. All of these devices require some form of conveyor or transferring system. Conveyors are therefore an integral part of the packaging process and are elements or machines, which have their own reliability and design issues. Integrating all of these types of machines and mechanisms into one seamless system must result in the consistent regular flowing movement of inputs, packages and cases that enter into the packaging line at specific points and are assembled, identified, verified and shipped to fulfill customer needs. CONCEPT PRINCIPALS FOR INPUT & PRODUCT HANDLING 1. Once you have it, don t let it go. Having it means complete physical or electronic engagement so that the input is always defined, measured, trapped and has no ability to wander or oscillate. Most operations considering the direction of flow have elements of no control (Freedom in two directions), partial control (Freedom in only one direction) and full control (No Freedom). Never have "no control" in the center of an automated mechanism. Eliminate even partial control for high-speed machines. 2. Eliminate or minimize input and package manipulations. Combine manipulations. 3. Eliminate or minimize change relating to displacement, velocity, acceleration and/or inertia in direction and magnitude. 4. Don t change pitches in transfer to transfer through machine.

3 5. Eliminate or minimize interfaces and handshakes. 6. Always interface using complete interlocking or hand shaking pass off within a defined boundary, not at a point or area-of-float (no control). The interface position tolerance must be smaller than the operational functional window. 7. If manipulations and/or handoffs are required because of overall design constraints, always match motions (intermittent to intermittent, continuous to continuous). 8. For cycles above 60 per minute, continuous is superior to intermittent. 9. Keep it simple, meaning the fewer moving parts the better. Ideal high technology means one moving part. 10. Design for robustness, which means it takes a beating but keeps on producing quality products. 11. Design for flexibility, which means it can take a wider range of product sizes or material than is needed at the present time. 12. Design for fault tolerance, which means it is forgiving or auto-adjusts for inputs inside or even outside of their specification range, but still can produce a quality product. 13. Never assume an operator will control the proper logical sequence of events for optimum performance or corrective action. 14. Good enough is in reality not good enough. Profits of successful consumer products companies are heavily influenced by the performance of their packaging lines. One common cause of low performance is a less than optimum choice of concept, which will dramatically effect integration. Bad integration is the result of the wrong concept and/or improper execution. Design and installation of Conveyor Systems Traditionally, conveying systems were designed without paying much attention to drive dynamics, the forces imposed on the conveyor and product, or the effects of these forces on container stability. Present designs are based on the average running speed requirements and mechanical longevity. This results in typical design formulae considering only rough estimates of the loading (forces); combined with factors, which represent the number of start-ups and the amount of product slippage. Most present chain manufacturers in North America typify this approach. In recent years, increasing demands, economics, and environmental concerns have placed enormous pressure on production facilities to increase operating speeds, reduce wastage,

4 reduce rework and cut manpower requirements. These changes have pushed traditional design methods to the limit of there effectiveness. In addition, the aesthetic appeal of complex container shapes and the use of lightweight plastics has resulted in a new generation of stability problems associated with the transport and control of containers by conveyor. Transfers Between Conveyors and/or Machines The most common types of conveyor-to-conveyor, conveyor to machine or machine to conveyor transfers are: 1. butt end. 2. side transfer. 3. S-inline transfer. A butt end transfer is when two conveyors are literally put together inline in such a manner that one chain is short of touching the other chain by at least 1/4. A dead plate or small rollers are placed between the gap to allow the product to run or be pushed across. It is not advisable to use the dead plate transfer for the following applications: Unstable packages with a difficult shape and/or high center of gravity. Conveyor speeds above 150 feet per minute. Package is shorter than the dead plate or transfer roller such that the package will hang up and wait for the next package to push it off. Packages whose base has sharp edges. Twin sided driven belt conveyors can be used to grip most types of containers (especially with vertical side faces) and laterally carry them over the dead spot on the butt end transfer. Using this technique, high-speed transfers can be accomplished under specific conditions. A side transfer is when two conveyors are placed side by side so that the package is guided via angled guide rails from one conveyor onto the other. This insures that the package will be controlled and powered from one conveyor onto the next. The items one should consider when designing side transfers are: The gap between chains should never exceed 1/8 (3 mm). The downstream conveyor should be about 1/32 to 1/16 (1 mm) lower than the upstream conveyor for good transfer. The angle of cross transfer should not be greater than 15 degrees. For difficult shapes or higher centers of gravity less than 10 degrees is advisable. Guide rail shape can be critical for difficult shapes. Conveyor speed differentials can be very critical. Minimize speed differentials. Because to the angled transfer to the conveyor pull, side forces on the container or input can be substantial and effect performance.

5 A S-curve transfer is when two conveyors run parallel together in an elongated S form so that the guide rails are straight and the conveyors flex at the transfer. This insures that the package will be controlled and powered from one conveyor onto the next in line with minimal side forces and maximum control. Although, this type of conveyor is more expensive than the traditional side transfer, the control for difficult shapes is superior and guide rail change over to other sizes is quicker and more accurate. The items one should consider when designing S-transfers are: 1. The gap between chains should never exceed 1/8 (6 mm). 2. The downstream conveyor should be about 1/32 to 1/16 (1 mm) lower than the upstream conveyor for good transfer. 3. Conveyor speed differentials are a minor consideration. 4. The side flex radii should exceed minimum chain specifications. Only side flex conveyor chains can be used. 5. The idle and drive ends should be straight sections for about 12 inches. 6. Consider clean design and easy cleaning, since this design requires more maintenance. In general, conveyors are critical elements in any packaging process, which are grossly misunderstood and poorly manufactured. This is mainly due to non-packaging people and some packaging people thinking that conveyors are non-value added items that are: not a major item or consideration. the last think considered in line design and the last item purchased. cheap units for moving inputs from machine to machine. one conveyor type is as good as another. This thinking can be disastrous for many packages. Speeds, feeds, dynamics and loads for Interconnecting Machinery The common requirement of conveyors is to transport containers from machine to machine, and finally to storage facilities. In general, each machine will have different requirements in terms of container spacing, linear infeed and outfeed speeds, method of infeed, container orientation and container control. In order for the production line to function smoothly, the conveying system must provide the required changes in pitch and speed, and must also serve (when required) as a reservoir of containers to help level out fluctuations in machine operation. In addition, the conveying system may also have to convert from single to multi-lane or mass flow and visa versa. All of these requirements must be met without tipping, spilling, jamming, or damaging the containers. In the past, container transfer rates were relatively low (e.g., up to 300 bottles per minute) and the containers were geometrically simple with low centers of gravity (e.g., short, round bottles) Recently however, higher speed and performance requirements and more sophisticated machines have resulted in increased line rates (up to 2000 bottles per minute in a brewery). Also, the aesthetic appeal of complex shapes and the use of

6 lightweight plastics have resulted in a new generation of stability problems associated with conveyance systems. Traditionally, line speeds have been dictated by the operating capacity of the filling station. As a result of these changes, however, the performance of today's lines are limited not by the capabilities of the machinery employed but by the conveying systems used for package transport. In an effort to provide conveying systems, which meet these new demands, a number of long-term issues should be resolved. These issues are: 1. Develop a systematic approach to the design of conveying systems, which minimizes the speed differential from one conveyor section to the next. Impact tests on inputs and packages should quantify the requirements. 2. Makes optimal use of the combination of motors, gearboxes and sprockets to give the desired operating characteristics. Ideally a common motor and gearbox for all conveyors would be desirable and the elimination of sprockets ideal. 3. Minimize the number of different elements in the electrical and mechanical drives and hence reduce maintenance and spare parts requirements. 4. Derive mathematical models, which describe the dynamics of conveyor-to-conveyor container transfer. 5. Determine and test the effects of container geometry and stability on the dynamics of a given conveyor type. 6. The forces acting on both the inputs and the conveyors when transporting at various transfer rates. 7. Build computer simulated models of buffer areas in conveying systems to study the effect of speed, buffer size, buffer type and transfer design on input or package stability. Buffer design should be based on the 80% rule or the mean to of failure and mean time between failures concept. 8. The effect of input shape on the flow of inputs such as containers through an accumulation areas or combiners. Compatibility of Interconnecting Machinery A packaging line should try to balance its machinery with compatible function type. Function type means the method of operation, which can be either continuous or intermittent. Most low speed lines generally have intermittent motion machinery. Highspeed lines usually have only continuous motion machinery. Medium speed lines could be a mix of both. There usually are tremendous problems when an intermittent machine is coupled to a continuous motion machine. The best way to solve the mix is to place a

7 buffer between the two elements. These two motions are almost impossible to line shaft mechanically but could be electronically line shafted, but with great difficulty. It is possible to effectively run an intermittent motion on top of or within a continuous motion machine or visa versa. These types of new high technology machines require proper designs and well-trained skilled operators. Integrating Manual Operations With Automatic Machinery Human beings are the most resilient, flexible and adaptable element in the packaging process. Unfortunately people have the following characteristics: They are the most unreliable on a day-to-day requirement. They are the most inconsistent and quality varies from person to person. They have the least endurance versus machines. They are greatly restricted in weight lifting, reach and movements, especially if they are repetitive in nature. Because of this, great care most be taken in designing human involvement in any packaging process. In general, as the packaging process goes faster and/or weights or manipulations increase, it is imperative to design out all human intervention just from the standpoint of health and safety, regardless of cost justification. If human involvement is to be designed in as part of the packaging process such as packing, palletizing, etc., then the following conditions must be considered. 1. Ergonomics or the minimum human movements to complete the required task at the proper heights and weights. Rotating or cyclic movements of the wrists, neck, torso and arms should be eliminated or minimized at all costs. 2. Safety! Safety! Safety! 3. Eliminate or guard pinch points in the work envelop. 4. Maximum noise levels should be 80 decibels steady and 85 decibels for short peaks. 5. Establish and maintain strict house cleaning rules. 6. Minimize walking and relieve long-standing periods. 7. Rotate people after predetermined time periods. Line Shafting Machinery - Mechanical & Electronically There are two types of input control - full input control and partial input control. Full input control is when a mechanism or machinery secures or captures the input properly and never loses that positive control until several defined assemblage procedures are complete. Full control has both speed and position locked. Partial control means that for the assemblage procedures there is full control, but between assemblages, control is by speed and backlog only. For this section, we are only considering full control.

8 To gain maximum control and positive transfer at medium to high speeds, one can do one of several things such as: 1. Buy machines that are monoblock or do several operations on one base, such as rinsing, filling and capping. 2. Mechanically or electronically line shaft several machines and their conveyors together such as air cleaners, fillers and cappers. 3. Mechanically or electronically line shaft several machines together and tie in their conveyors electronically via variable frequency AC motors. The best technology to use for full control is servo technology. Conclusions The minimum following six factors must be thoroughly investigated and the results applied to eliminate problems occurring due to integration effects. 1. Design and installation of Conveyor Systems 2. Design and installation of Guide Rails and Handling Control Components 3. Speeds, feeds, dynamics and loads for Interconnecting Machinery 4. Compatibility of Interconnecting Machinery 5. Integrating Manual Operations With Automatic Machinery 6. Line Shafting Machinery - Mechanical and/or Electronically All machines and equipment impinging on the packaging process must be considered from the standpoint of integration. The principles of proper integration for material handling of inputs and packages as outlined in this paper should be adhered to as much as possible to achieve optimum reliability and performance. All of these machines and equipment require some form of conveyance system to transport product or inputs from one machine to the next. Conveyors are therefore an integral part of the packaging process and are critical to the function of the packaging process. Profits of successful consumer products companies are heavily influenced by the planned integration of their packaging lines. Original equipment manufacturers (OEM) are generally poor integrators of packaging processes, because their thinking is more machine based then system or process based. Those OEMs that have integration skills, their skills are centered around their equipment and possibly the immediate connecting machinery. True integration specialists are a rare breed, but if they are part of your team the results are consistent and profitable. This paper only gives a flavor and some highlights of the proper concept of integration.

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