Lifting loves a vacuum

Vacuum lifting is not only for small light objects, but concrete prefabricated units, big machines that need delicate handling, porous sacks and carboard boxes, pallets of shrink-wrapped tins: with suitable end-of -arms suction attachments all of these and more can be handled quickly and ergonomically by vacuum lifters, saving back strain on staff and increasing speed and efficiency. And vacuum lifters are becoming more capable and more sophisticated all the time.

French specialist Coval, for example, offers vacuum grippers for automated applications, from lifting single parts to complete layers. The range is equally suited to equipping either cobots or robots. A cobot, - short for collaborative robot - for those new to the word is a production robot, similar to those used, for example, on automobile production-lines, but designed to operate alongside human workers.

To avoid the possibility of causing injury Cobot arms are therefore lighter and slower moving than those of standard industrial robots.

Coval’s complete range of vacuum grippers can be applied at various points along the whole production line, from the manipulation of individual objects to palletizing a full layer of product at the end of the line. It includes three complementary series, starting with the ultra-compact CVGC models. Further up the range is the CVGL series of compact and lightweight end effectors for robots. At the top end is the MVG modular series, which is fully configurable.

The company’s CVGC carbon vacuum gripper is not just an adaptation of an existing product but a plug and play product designed specifically for cobots. The smallest model weighs less than 1 kg. Its lightness comes from its being made of carbon-fibre and allows the optimum use of collaborative robots while still being strong enough to preserve their lifting capacity. The vacuum generator, control cartridge, vacuum switch, and silencer are grouped together, in a compact function block. The CVGCs come with a foam grip interface suitable for lifting many materials and which is available in three sizes up to 320 x 160 mm. “The attachment interfaces and connectivity are adapted to the particular cobot model, which means that the CVGC fits on all types of cobots,” says Stéphane Garcia, marketing and communication manager, Coval.

Coval’s CVGL range of vacuum grippers is smaller and lighter still, which means they can be integrated into low-power robot manipulators. Its MVG modular vacuum gripper is mainly used for heavier payload robots and palletizers.

“The MVG grippers can be multi-zone, equipped with several independent gripping zones. That makes it possible to ensure staggered or multiple pick-up and drop-offs – you don’t have to pick up everything first and drop them all off before picking up a second load. That gives optimized vacuum management as well as a reduction in leaks and consumption,” says Garcia. “It is particularly useful for optimizing pallet layers.”

Piab also has cobot grippers, and it too finds that small and light is right for the application. “The smaller and lighter a cobot gripper, the more lifting capacity is available for the task of moving goods,” it says - and the rise of e-commerce means that moving goods from, from example, from a shelf into a box for shipment is an ever-increasing demand.

Its mini cobot gripper, announced in June this year, weighs in at just 270 grams; it claims it is probably the lightest cobot gripper in the world. It lifts loads up to 5 kilograms and can be flexibly equipped with a wide variety of suction units.

To produce the vacuum that powers it, Piab has a system which it calls COAX, which uses compressed air to create vacuum via the venturi effect; it says that the technology can provide three times more vacuum flow than conventional systems, allowing increased speeds while consuming less energy.

The combination of a COAX vacuum pump unit with Piab’s Quick-Click plug-and- play-type tool changer allows the user to switch from one gripper plate to another within seconds without any tools.

Because of the high initial vacuum flow it offers a safe and quick hold; using it allows the mini cobot gripper to pick up almost any part, from tablet boxes to toothpaste tubes, whether packaged in paper or plastic boxes, in bags, or loose. Suggested applications include E-commerce, logistics and warehousing, packaging and any fast-moving consumer goods or food application where cobots are used.

Piab also has a newly-developed Cobot palletizing tool or CPT. It has a multi-zone vacuum gripper surface which can pick several boxes even of different shapes in the same cycle, and can do so at high speed; the end result is that it can palletize more boxes more quickly leading to more pallets prepared for shipment each day

It, too, goes for lightness; picking up several cartons at once reduces the number of movements needed. Combine that with the reduced weight on the cobot arm from the gripper itself and the result is that wear on the arm is greatly reduced leading to a longer cobot lifetime.

The tool can be combined with Piab’s IO-Link ready piSMART valve unit to provide Industry 4.0 capabilities, such as predictive maintenance to reduce downtime. When it is used with a COAX vacuum generation air consumption is again reduced while still obtaining secure lifting power at maximum payload.

Aerolift, based in Barneveld in the Netherlands, has two innovations in its range. Vacuum lifters are often provided with exchangeable suction pads so that the same lifter can be used for products of very different dimensions and weights. Aero-lift already used a quick coupling system for change-overs, but it has now reduced the number of actions required to connect and disconnect suction pads to just one.

The pad is connected with a twistlock, a commonly used locking system.

Previously, before changing suction pads the vacuum hose had to be disconnected, and then reconnected when the new pads were in place. In the quick-change system this happens automatically. “So, it saves an extra human action and human effort. The quick-change system makes changing suction pads easier, faster, and reduces the risk of incorrect connection,” says Aerolift CEO Robert Lemm.

Aerolift’s other innovation, its EU-series, is a modular vacuum lifter. “It satisfies a wish that has existed in the worldwide market for some time: an affordable lifting solution for relatively simple applications,” says Lemm. “It is intended to provide a wide range of solutions within a certain standard configuration. This allows us to deliver higher quality in a shorter time and at a lower price.”

The EU-series is intended to handle small airtight products up to 6 tons. “Think precast concrete elements, metal plates, and pipes that are picked up, for example, by an overhead crane,” he says.

An EU vacuum lifter consists of at least two modules: a vacuum unit and a suction pad. “Additionally, you have a beam, crossbeam, and several options. Each module consists of a few options to choose from, and modules can be combined to give the most suitable lifting solution. Our team can advise on that. We can also offer a hybrid between modular and custom-made solutions; for example you could have an EU vacuum lifter with customised suction pads. We look at how to optimise the process beyond the machine,” says Lemm.

In the next few months Aerolift will also add an ES-series, a modular solution for heavier products up to 20 tons. The lifter will have an elongated shape and be suitable for long products such as steel plates and pipes.

Palamatic’s tube lifter system uses the same vacuum to both grip the load and to lift it. Instead of a robot or cobot arm the gripper is attached to the end of a vertically-hanging flexible tube; when the load attaches to the gripper it seals off the air inlets and thus increases the vacuum in the tube – which thereupon concertinas, contracting vertically to reduce its volume, and in the process lifts the load.

The operator controls the vacuum flow using a simple, finger touch operating valve. Increasing the vacuum draws air out of the tube and the load is lifted. Reducing the vacuum allows air to enter the tube and the load is lowered.

The combination of the lifting and gripping functions requires no special interlocks or devices. A quick acting non-return valve and a suction force to lifting force safety factor of 2.5 prevent the load from being inadvertently dropped even in the event of a mains power failure.

Vacuum tube lifters are ideal, say Palamatic, for applications where the load is positioned vertically below the lifting assembly; they are not suitable for off-set or cantilevered load handling processes such as loading shelves or racking other methods, for which Palamatic’s Manipulator or PillarLift range are better.

Palamatic has a speciality in stainless steel lifting equipment. The fully stainless steel S-Line, which also uses vacuum tube lifters, is for applications such as food and dairy processing where avoiding the risk of contamination to the product is essential. The system uses FDA-approved suction seals and can be provided with a wipe-down lift tube cover. Options for stainless steel gantry crane systems are available where full protection is required. The system is suitable for handling packaged food products or food blocks such as frozen meat or blocks of cheese.

Yaplex is based in Chesterfield and has automotive, manufacturing and aerospace clients. “Vacuum lifting can be used in almost any industry,” says sales manager Richard Deakin. “On a production line, for packing or palletizing it lends itself to anything where a smooth surface is available, such as wood panels for example.

Yaplex offer three systems. The Ducto is a vacuum tube, working on the principle described above. “It can lift up to 300kg”, says Deakin. “Vacuum tube systems have the advantage that operating them is simple and intuitive, so it is easy to use. And they require a lower level of capital investment which makes them more cost effective than other handling systems.

“Most vacuum systems are either suspended form a crane or monorail or from a forklift truck. We can also provide standard systems that run on mains or on battery power, or a venturi system that uses compressed air to make the vacuum. The venturi system is especially economical when you use it with compressed-air-operated manipulator arms, because you don’t need to run any power or hydraulic cables along the arms to the suction pad; you just use the air that operates the arms to provide the vacuum also.

“Porosity is an issue; but the object to be lifted does not have to be completely impervious to air. When you lift a load with a leaky surface, such as a paper sack, you will lose vacuum, slowly or quickly; but the sensor controlling your vacuum pump will realise that and set the pump going again to restore the vacuum. So if you are suspending a piece of sheet steel, it will maintain its vacuum without power input almost indefinitely, all day if you like. Chipboard or MDF in the other hand will slowly leak, causing the pump to cut in now and then. Cardboard will leak rather faster. All you need to do is ensure that your vacuum pump is strong enough to overcome the porosity of the loads that it will carry. You can suspend a 100kg piece of steel using a smaller blower than you would need for a 25kg paper sack.”

So far we have been talking of lighter-capacity lifting on production or packaging lines. In the industry jargon these are low-vac. But concrete and steel slabs, pipes and stone handling are higher capacity lifts and need to operate therefore on correspondingly higher vacuums.

Paul Waton is managing director of the Vacuum Lifting Company, based in East Kilbride, Scotland, which has been making such lifters for over 30 years.

“High-vac systems operate at 40% vacuum or more,” he says. “At that degree of suction you can lift almost anything as long as it is not porous: pre-formed concrete, steel slabs, you name it. We do capacities from 100kg up to 20 tons.

“The vacuum comes from standard pump units which are generally battery operated, at 12V; so our attachments are commonly fixed to a vehicle, a forklift truck or an excavator or site crane for example – many of our customers work outdoors in stock yards or on sites. We do have off-the-shelf units: for example, our HX300B which is a 300kg capacity 6-pad lifter for handling thinner metal sheets, or the SKDT1KB single pad lifter which goes up to 5000kg capacity for heavy-duty straight- or side-lifts of steel or concrete or stone; but we mostly make bespoke designs to order. They can have hydraulic powered tilting systems for, say lifting and then turning a concrete slab.

“We do forklift attachments with 90 degree or 180 degree tilting; those are popular with people who do laser or water-jet cutting, and concrete panel producers and steel fabricators.”

Other customers include Airbus, Thyssen Krupp, and BAE systems: “Aerospace is another big sector for us, lifting wing sections and the like. We have just completed an order from the Faroe Islands, from a boatbuilder who needs to lift steel hull sections.”

The moral of all this is fairly simple. Nature might abhor a vacuum, but those who need to lift a load can find one rather useful.