Typhoo cuts tea blending costs by a quarter

Citation

(2003), "Typhoo cuts tea blending costs by a quarter", Industrial Robot, Vol. 30 No. 1. https://doi.org/10.1108/ir.2003.04930aaf.003

Typhoo cuts tea blending costs by a quarter

Typhoo cuts tea blending costs by a quarter

Keywords: Packaging, Materials, Handling, Robots

Premier International Foods has reduced by more than 26 per cent, the cost of converting a tonne of tea into tea bags at its Typhoo production plant on the Wirral, near Liverpool. This follows the installation by Motoman of two turnkey robot cells to take over from manual sack handling last summer (2001), at which time the whole process was automated including mixing of the blend. According to Engineering Project Manager, Phil Valentine, who was responsible for the initiative from start to finish, payback on the investment will be within 2 years.

Sack handling was previously very labour intensive, with 15 men depalletising the 70 kg sacks of tea over five overlapping shifts during a 24 h period. Even with the assistance of vacuum lifters, it was still an arduous job with Health and Safety implications. Now that the robots perform the same function automatically, the number of people has been dramatically reduced. Indeed, only six staff are now needed to oversee all blending activities, from raw tea intake, through robot cell operation, sack opening and blending to filling. The remainder of the former depalletising operatives has been redeployed elsewhere within the factory.

Throughput of the system is now impressive. Said Mr Valentine, “We have processed 196 tonnes in 12 h using the robots with both cells running flat out whereas our best performance with manual handling was 80 tonnes in the same time period. It means that whereas we were working 24 h a day, 7 days a week, now we operate a double day shift, Monday to Friday.”

Both cells are identical and operate side by side but independently (Plate 3). The robot model is the 4-axis SP100X-160 and each is programmed using the latest XRC controller. Should one cell break down, pallets can be transferred across to the other so that blending can continue. This is an essential precaution as blending is the lifeblood of the factory, so any interruption brings everything to a stop. In each cell, pallets loaded with tea sacks are placed by lift truck onto a loop conveyor and the settings are entered on the central control panel. If empty pallets from previous blends are present on the static stations, these are unloaded.

Plate 3 One of the Motoman robot cells at Typhoo, showing a tea sack being handled using a vacuum gripper onto an inclined conveyor for transportation to the blending area

The pallets are indexed around the conveyor until the first is below a vision system camera. When the start signal is received, a photograph is taken of the first pallet which moves to the unload station. Meanwhile the vision system senses the rectangular outline of the first sack and works out the centre, passing the data to the robot which uses the information to position a vacuum gripper above the sack. The robot already knows the height of the sack as the control system tells it which level is being depalletised. The gripper can therefore be traversed rapidly to within 400 mm above the sack, minimising the cycle time. All sacks on the top layer are sequentially placed on an inclined, linear powered conveyor leading to the blending area above.

The pallet is then released to index around and a picture is taken of the next pallet which moves to the unload station and the cycle starts again. The process continues until the last layer is left on the pallets. After these sacks have been removed, the pallet itself is unloaded by the robot and stacked up to ten high on three static stations using a set of electrically actuated claws mounted around the vacuum head on the dual purpose grippers. While this is happening, the next blend is loaded onto the loop conveyor by lift truck via an input station. The result is that changeover from one blend to another is now faster than before, taking only 7 min.

“Hessian sacks containing coffee beans can be spiked but this obviously does not for work for tea. We considered a handling system whereby the gripper lifts the sack from underneath, but this would have increased the footprint of the cells. Motoman was able to source all the required elements to complement its robots including the conveyors, electrical panels and dual purpose grippers.”

For further information, please contact: John D’Angelillo, MD, Motoman Robotics (UK) Ltd, Unit 2, Johnson Park, Wildmere Road, Wildmere Industrial Estate, Banbury, Oxfordshire, OX16 3JU, UK. Tel: 01295 272755; Fax: 01295 267127; E-mail: johnd’angelillo@motoman.co.uk;Web site: www.motoman.se