Despite their importance, conveyors and container handling technologies are often an afterthought. They shouldn’t be. Things to consider:
1. Buy the conveyor pre-integrated.
When considering a new line, it’s often smart to buy the conveyor as part of the machine. If you’re buying a packaging machine as a replacement, it might be tempting to retain the old conveyors, but be aware that the match might not be optimal, especially at transfer points. If the machinery builder supplies the conveyor already integrated, it reduces installation costs (versus purchasing a separate conveyor), installation time, and line commissioning of I/O devices. This will also ensure that no stand-alone control cabinet is required and that all variable frequency drives (VFDs) and devices, and the power panel and PLC control panel are assembled onto the conveyor legs and frame. All the information will show up on one screen—motors, alarms, and controllers—making things simpler for the operator, technicians, and engineering staff.
2. Understand how your containers behave.
You need to consider package geometry, center of gravity, and mass when specifying conveyors. For example, empty PET bottles act differently under pressure compared to filled bottles; hence the conveying and container handling has different requirements on different stages of the line. Fully understanding your package geometry can also help you avoid excessive back-pressure. When you’re feeding a product, excessive back-pressure can force a package into a machine before it is ready. Whether you’re feeding, sorting, or unscrambling, back-pressure values are all dependent on the dimensional stability of the package; so, you need to completely understand your package or container spec when asking a vendor to design a starwheel or a timing screw around the package. Everything depends on form and shape. Starwheels are good for certain shaped containers, whereas timing screws are often better for rounded containers.
3. Realize that it’s all about control of the container.
Conveying is rarely, if ever, just free-flowing product or containers. Proper spacing, position, and orientation must be maintained. The goal is to ensure that product flow can take place within a given footprint. Conveying is not just a means to get something from one machine to the next. You must understand what the next machine can handle. You need to understand the following:
- Whether container control may best be achieved by single-file or mass conveying
- How many lanes should be used
- Where is the optimal speed
- How to maintain control at the desired speeds with an unstable container
- Whether the container needs to be controlled by the neck or the base
- Whether or not control can be maintained if something downstream breaks and conveying systems stop
- Is there adequate clearance and access to easily clear a conveyor of jams? Or will things slam into each other, lock up your machines, and stop your line? Slower speeds may mean a higher chance of success
4. Carefully consider unique features and options.
Some conveyor manufacturers offer a simplified change of direction, having integrated features into conveyors that turn packages at a 90-degree angle. It’s done with rollers in the conveyor mat top, and you can adjust the direction of the turn to your specific floor space. Similarly, some engineers prefer to have VFDs on every conveyor. It’s a great feature, but sometimes that extra hardware is an unnecessary expense. Depending on your product, some things will never need a change in speed. Think about whether the extra VFDs just add unnecessary complexity, or are worth it for future flexibility.
5. Pay close attention to friction, cleats, and changes in elevation.
When conveying unpackaged foodstuffs with vibratory conveyors, it is wise to minimize drops and stick to a general guideline that no drop should ever exceed six inches. Similarly, when conveying delicate product, reduce friction by seeking out the most nonabrasive conveyors. If you bounce your product against redirecting plates, as opposed to a soft landing on other product, you will end up with less good product in the box. Timing screws can offer gentler handling compared to starwheels, and also tend to be more compact.
6. Consider a robotic solution to product handling.
Product handling can be an ideal robotic application on the packaging line. The most successful applications tend to have these characteristics:
- Where the product comes in randomly or not oriented, and must leave in a specific orientation/order.
- Where there is a degree of product variation in size or shape (example: frozen egg rolls/burritos).
- Where there is high changeover and plans for totally new products/packages in the near future.
7. Look for ease of maintenance.
The level of technology involved should be a factor in evaluating the equipment’s total cost of ownership, as it can directly affect the type of maintenance required, and the skill level of maintenance personnel. A sometimes-overlooked component of good maintenance is spare parts inventory and equipment documentation. Determining which parts should be kept on-premises can be the difference between a short stoppage and an extended one.
8. Put safety first. Conveyor accidents hurt both associates and companies.
They can negatively change lives, while impacting productivity, increasing Worker Comp insurance and even result in OSHA fines. Safety hazards, especially pinch points, must be designed out. While it is a fact conveyors have moving parts, proper safety design should include guarding of drive components, guarding of the return side of the belt or chain, especially if there is a long loop of belting (cantenary sag). Use of “pop-out” rollers at conveyor transfers can prevent associates from getting pinched between two moving belts. Carefully look at where Emergency Stop safety push-buttons are located. For a long conveyor run where there is not easily accessible spot, consider running an E-STOP Pull Cord over the top of the conveyor. A good practice is to locate a disconnect switch close to each conveyor motor to facilitate LOTO. Finally, in areas where associates need to be on both sides of a conveyor, strategically place cross-over platforms, guarded “duck under” sections, or ideally, design in gripper chain or vacuum elevator / lowerator conveyor sections to allow operators to easily walk under the line. Not every aspect of safety, however, can be factory-ordered. Your company should have safety policies that include employee training. There are federal government-compiled statistics on industrial accidents, categorized by type of equipment. It’s a good reference source to assure that employee training, at the very minimum, addresses the most common causes of conveyor accidents.
9. Pay attention to sanitation.
For food-contact applications, pay attention to sanitation and cleanability. If you’re trying to remove cross-contamination between products, make sure the conveyor belt design doesn’t trap particles. For food, beverage, or pharma applications, look for conveyors with a minimum of nooks and crannies that can harbor bacteria and dirt. Verify that if the conveying chain is swabbed, it removes 100% of the product. (That will be especially important for compliance with the Food Safety Modernization Act.)