Getting a grip25 November 2019
Panel products can be awkward to handle but, as Julian Champkin from WBPI sister title Hoist magazine explains, lifting technology is up to the challenge
Panels can pose lifting and handling problems within the factory. They are large, they flex and in the age of Industry 4.0, and ‘batch size one’, where today’s customers demand mixed batches, picking and sorting from the production line stacks is necessary.
But panels, even moderately sized ones are awkward to lift, as well as heavy. Hand-picking large flat items from several different stacks, each of different specifications, and piling the unique selection into a single stack for delivery to a specific customer, is a task that normally requires many employees.
German company euroTECH Industries has a solution to the challenge of batch size one sorting and delivery, claiming it as the first customer-specific Industry 4.0 vacuum lifter. It will have many applications, but euroTECH has designed it for panels and other large, flat-surfaced products, and is demonstrating it on wood-based panels.
“Customers are increasingly calling for individual production and faster deliveries,” said euroTECH chief executive officer Thomas Schultz. “Production and storage departments have to keep up with these demands. Orders of ever-smaller batch sizes require efficient, cost-saving production and storage management.”
The euroTECH picking system consists of multiple pallet positions, side by side, each containing panels of a particular specification. The lifting itself is by multiple vacuum cups on a lifting frame. A trolley with the vacuum lifting frame moves above the pallets, picks a panel, and moves and deposits it on the customer’s pallet. An employee operates the user interface of the system to specify source and target stations and picking volumes.
To start its fully automated picking cycle the machine requires information about which vacuum circuits to activate for the different loads. This data is stored in a database or a bar code. Picking then takes place automatically.
The system is equipped with multiple sensors to prevent errors. For example, it compares the weight of each lift with previously registered data. If the weight is a match the machine carries out its cycle. If there are deviations between the source and target weight, the cycle is interrupted and the machine produces an error notification.
Such an error would occur if the vacuum lifter raised two panels at once. Adhesion is a problem that can frequently occur when picking wood-based panels from a stack: large, flat panels piled one on top of another do not easily admit air between them, so that if the top one is lifted, the one below may come with it, held to its upper neighbour by partial vacuum above and air pressure below.
EuroTECH has incorporated a solution into its order picker – lifting up the corners of the load allows it to flex and let in air. EuroTECH’s lifters do this by using suction bellows cups at the corners of the lifting frame.
It is good practice also to create delivery stacks that are well aligned, not merely for neatness but to protect sensitive surfaces and edges. As an option at an expansion stage of the order picking system, a floating vacuum lifting frame can make up for misalignments of up to 50mm in the customer’s stack. Integrated linear actuators adjust the position of the floating frame using the edge of the previously stacked panels as a reference. A maximum misalignment of 2mm is claimed for the system.
With the fully automatic order picking system, users can effectively pick small and single-unit batches, said Mr Schultz; it also eases the physical work involved and creates safer conditions for employees.
Further again down the wood processing and production chain, furniture factories also throw up handling challenges. Here the panels need not only to be moved, but manipulated: tilted to the vertical or other angles, or fed into CNC cutting machines, with high degrees of precision. Again vacuum lifting, of various kinds, is the preferred solution.
TAWI, which is headquartered in Sweden but has a UK office in Northampton, produces vacuum grippers able to move wood sheets weighing 500kg or more when they are hanging horizontally and up to 250kg when vertical and provide a large range of motion and precision.
These loads would otherwise require two employees to move each panel individually but with the vacuum gripper, one person can handle the panels, tilting them a full 180° if necessary.
Handle controls are ergonomically designed and fully integrated with the hoist; with a button push, the operator can activate the vacuum, lift up or down, control the vacuum level, or tilt and release the load. Sheets and panels of all densities and dimensions are handled equally well, said general manager Mike Wooster.
The SSP vacuum suction spider from Schmalz has suction cups that are specifically designed for the timber industry. A special soft sealing foam on the cups handles work pieces without damaging them or leaving marks, so that they can be coated later on without surface imperfections.
Schmalz, which is headquartered in Germany, has a different solution to the problem of adhesion between boards. When handling porous or semi-porous work pieces such as MDF or particleboard, an integrated separating function ensures that vacuum between the boards is halted by restricting the flow of air from the suction cups. In this way, only one work piece is picked up and held.
A double sealing lip on the inside of the suction cup is designed to give a very tight seal on rough and smooth surfaces. The special structure of the bottom surface of the suction cup allows for extremely short cycle times and highly dynamic handling. The vacuum spider is protected by check valves on every suction cup. If only some of the suction cups are covered, the uncovered ones are switched off. This makes it possible to handle panels with many different dimensions.
“The vacuum spider is made up of a number of individual components that are perfectly tailored to one another, which makes it possible to adjust the device individually for every process,” said Andreas Dolker, manager for corporate communications at Schmalz.
One user is a manufacturer of prefabricated housing, who has to load long, heavy boards into a machining centre. A Schmalz vacuum suction spider is used to achieve high reliability in this automated process.
Schmalz’s SSP suction spider consists of six area grippers. The wear-resistant sealing foam on the grippers is extremely durable and can stand up to work pieces with rough surfaces. Flexible spring plungers compensate for unevenness and differences in height so that the suction spider always grips reliably and with high precision. Two powerful blowers are installed directly in the gripper and provide the necessary vacuum.
The gripper is highly adaptable, which allows it to easily fasten to boards and beams of different shapes and sizes. The gripping system is attached to the hoist and can cover a very large work area. The hoist is controlled from a control panel on the machining tools.
The system helps to optimise the handling process and shorten production times.
Vacuum tube lifters are frequently used with vacuum cups. Schmalz has supplied tube lifters to a Swiss-based manufacturer of high quality wooden doors, for example.
In its semi-automated production process the heavy raw wooden panels used to be moved by hand between a number of different process steps, needing sometimes two employees for the task. To make the process more ergonomic and efficient, the company now uses the Schmalz JumboErgo vacuum tube.
The tube lifter is equipped with a flexible four head suction pad. For maximum flexibility, the suction pad on its cross beam can be moved to adapt it to the size of the work piece. An optional swivelling unit allows work pieces to be turned by 90° for further processing. Vacuum lifting, said the company, has reduced the numbers needed and protected the health of staff.