The design of a vacuum system has to take into account many factors. As well as the size, weight and texture of the load being handled, automation engineers need to consider everything from operating pressure and the size and type of generator systems, to gravitational and acceleration forces. "Generally speaking you can lift almost anything by vacuum providing you get the science right and calculate the holding force and suction pad diameter correctly," highlights Paul.
With a choice of hundreds of various end-effectors to accommodate different products as well as lots of different configurations, Pacepacker, a designer and manufacturer of robot packing systems, regularly seeks the expertise of vacuum handling specialist Vuototecnica. "The team has a vast amount of knowledge and experience in vacuum and can provide anything from pumps, cups, generators and pneumatic pump sets," highlights Paul. "This enables us to incorporate the very best and most appropriate automated vacuum handling solution to suit each customer's specific requirements."
The versatility of vacuum
The first phase of any pick and place installation is to specify the right system for the job. Generally speaking, there are four categories to choose from, each offering particular benefits depending on the application and manufacturing sector you operate in. Within each, there are also a huge variety of suction pad options, which can accommodate different products and suit all sorts of automation configurations.
A vacuum pump has carbon vanes inside. Working similar to a compressor, it relies on having a good seal between the pad and product. The vacuum pump is especially suitable for rigid packaging, such as ready meals or plastic pots, as the suction cup sits comfortable on the product. Its advantages are that it generates a high level of vacuum, even through small bore piping and valves. Also, the pump can be located away from the working area. The downside is low air flow volume, meaning that even a small leakage will result in loss of vacuum. Regular maintenance and good filtration is also essential, to prevent expensive damage to the pump body and vanes.
The benefit of a high air flow pump is even when the suction pads don't make 100% contact with the products; it will still pick them up. That's because the mechanism generates a high volume of air flow, much like a domestic vacuum cleaner. This type of vacuum is ideal for handling pots of cream or yogurt or fresh pasta sauces, as well as bagged products, like crisps or products with rough or porous surfaces. Advantages of this system are its tolerance to leakage and the ability to mount the pump away from the working area. What's more, the pumps are low maintenance with no wearing contact parts.
Vacuum generators use compressed air and offers high efficiency when picking up and moving product grouped together, for example four individual pots of dips. Because of the high vacuum, even if the end-effector doesn't make good contact with one product, it will still pick up all of the items in the group. Compressed air vacuum systems can often be designed with a single coupling, and substitution times of less than a minute are likely to be dwarfed by upstream changeover requirements. Vuototecnica has applied this generator technology to create an innovative adjustable system for the handling of baked goods to overcome the challenge of crumbs, spices and flour clogging up the suction cups and vacuum system. Rather than installing a filter to collect this residue, it includes a two-way valve that generates a counter-blow, speeding up the release of product while also cleaning the suction cup.
The Bernoulli pump is another "ingenious design," emphasis Paul. Based on the principle devised by Swiss mathematician Daniel Bernoulli in 1738, it operates like a vacuum generator, conserving energy without coming into physical contact with the actual product. "It can pick up high-end products, such as perfume packaged in cellophane without damaging the outer wrapping," explains Paul. "This is especially useful for thin packaging material, such as cling film, and for direct contact with food items, as it offers gentle product transport."
Take the cup challenge
Having selected the most appropriate vacuum system, manufacturers have a choice of over 1,000 end-effectors. "In terms of popularity, the vacuum gripper offers the greatest flexibility as the valves can be tailored to the specific product being picked," explains Jonathan Plumb, Vuototecnica UK's Managing Director. Suited for gripping and handling small objects with flat, slightly concave or convex surfaces, another benefit of vacuum grippers is they can be multi-functional. One large gripper can pick up the different size variants on the same line, for example multi-packs or individual cartons.
Suction cups, also part of the vacuum range, tend to be used for handling individual products, for example placing tablets into wrapping or individual chocolates into boxes. The soft lips of each suction cup can mould around each irregular shaped item, overcoming the challenge of differing size ratios and contours. As with most end-effectors, these can be manufactured using food-grade IP69K-certified plastics to meet hygiene standards.
Making light work of palletising tasks is the Octopus head from Vuototecnica. These bar-like vacuum systems can operate vertically, horizontally, inclined and even upside down and are widely used for stacking and moving heavier items, such as cartons, sacks and boxes. "With our Octopus system we offer customers a wide choice in suction plates, in different materials and shapes" highlights Paul. "From spongy foam pads for handling boxes and bags to suction plates with calibrated and self-cleaning micro holes suited for dusty environments, the grip of the Octopus is so strong it can optimize workplace safety."
Further considerations include the possible use of height compensators. These are sprung loaded features mounted onto suction cups and can pick up items with height irregularity, for example non-rigid outer packaging such as festive selection packs wrapped in cellophane.
What's more, food manufacturers that handle products with a delicate packaging film are increasingly adopting 'blow off' applications. Take salad bowls as an example. When packing into retail trays, the vacuum can sometime leave a small indent from the suction cap in the plastic film. With blow off, as soon as the vacuum turns off a jet of air is released to gently blow the product off.
"Vacuum handling systems offer food processors and contract packers a host of benefits," adds Paul. "Anyone considering automating a pick and place function should explore the options carefully. It's hard to ignore the longevity of vacuum; the concept has been around for decades, and functionality, flexibility and reliability consistently win every time!"
Vuototecnica regularly supplies its newest innovations for Pacepacker's 'try before you buy' facility, so customers can trial the very latest developments in testing conditions and how these tools might optimise the production flow in their own manufacturing environment.
