By Neil Elko and Paul Landers, ESS Technologies
Bigger isn't better when it comes to machine footprints in packaging facilities. As budgets tighten, manufacturers look for ways to get more production capacity from every inch of factory-floor space. The result is an increasing demand for packaging machinery that maximizes productivity while minimizing footprint. For design engineers, the challenge to think small can lead to big results.
A great example of this is the work we did to develop a very compact automatic cartoning system. It is time-consuming and costly to miniaturize a large machine. With complex machinery, all parts are interconnected, and the modification of one part generally requires modifications of all related parts. Both the performance and size considerations will be subject to change as the design progresses. These two constraints will conflict with one another as they jockey for importance.
Designing small means looking at market trends, determining where to set the performance goals on size and rate, and designing around the majority of what the target industry runs. The prevailing trend in manufacturing maximizes efficiency within the available space. Smaller equipment means more production with less floor space.
Compact size impacts decisions along the way. Generally, the larger the machine, the more time available to each process performed by the system. To maintain production rates with small equipment, the machine must complete each operation precisely on time at high speed. Material selection, therefore, is based on rigidity and vibration dampening. Precision equipment can move so fast that even minute variations in position can cause product rejections. Components and materials that counteract these possibilities must be chosen carefully. We are always on the lookout for products from our core suppliers to better our machines.
Small equipment design takes longer, but today's 3D CAD packages can greatly shorten design time. The designer's greatest challenge in small equipment manufacturing is to ensure that all moving components complete their task with enough time and space to avoid interfering with the next task. Simulation packages built into these CAD programs allow a designer to see and eliminate interferences before the machine is built. The real challenge then becomes going beyond that and planning for additional spaces and assemblies that meet the customer's special requirements.
Fast, simple changeovers are a common customer requirement. Changeover time is production uptime lost, and changeovers should be tool-less and fast with easily readable indicators for change points. Although space constraints on a small machine sometimes limit the choices for locating change points, the majority of change locations can use the same mechanism as those used on larger equipment if considered from the beginning. The design resulted in a machine with simple and reliable changeovers that uses change-parts only where absolutely necessary.
Ease of maintenance is important, but maintenance on small equipment can be more cumbersome. Proper machine design tries to maximize access to critical components and locations where daily operations could need access for cleaning, clearing or inspection. Proper component selection can minimize maintenance headaches. Although often more costly, high-end components usually last longer and require less maintenance. Some strategies for minimizing required maintenance include using "lubed for life" bearings, replacing chain drives with belt drives, and adding seals and wipers to linear bushings.
Thinking small resulted in a robust, reliable cartoning system that handles up to 60 cartons per minute while occupying considerably less floor space than most commercially available cartoning systems. The use of 3D and simulation software allowed the designer to specify the correct components the first time. By selecting components that balance cost and performance, the design team was able to create a machine that is easy to use, easy to maintain, and easy to fit into existing factory floor space.