New sorter helps No Limit carry out two weeks’ work in 2.5 days

On the day that No Limit’s new PTU (Push Tray Unit) sorter system went live at its multi-client distribution centre (DC) near Warsaw, the leading Polish third party logistics operator released a batch of 75,000 items for sortation, purposely choosing a difficult type of an order to put the system to test.

In its previous, fully manual way of working this would have taken at least two weeks to sort. Using the PTU sorter system, installed by SDI Group, No Limit processed the batch within 2.5 days - with fewer operatives and occupying less floor space than would be needed for manual sortation. This is a formidable taste of the performance that No Limit will be reaching when the system hits its forecast productivity.

"The PTU’s ability to handle a broad array of products from apparel to shoe boxes to small electronic devices has given No Limit a competitive edge by being able to offer an enhanced, faster and more accurate service to our retail clients,” says Mariusz Rączka, customer service manager, who at the same time was responsible for project management of sorter implementation project at No Limit. 

Serving the contract logistics market - including distribution warehouse management, B2B and B2C activities, co-packing, e-commerce and advanced trade and marketing projects - No Limit provides solutions for complex logistics challenges faced by small, medium and large companies throughout Poland and Europe. In addition to its 6000 square metre Warsaw DC, the company operates facilities near Poznan and Sosnowiec. 

Working in close partnership with No Limit, SDI successfully installed Phase 1 of No Limit’s sortation system, with associated controls and software, and trained staff at the facility to operate it. This was carried out on time for the operation to go live by the end April 2013 as planned, which was a vital objective given that No Limit had lined up tasks for the sorter, which could not be carried out in the given time manually.

The mechanical installation of the sorter, induction platform and the main conveyor carrying the trays, had to be aligned with the erection of the 7 m high mezzanine on which they are located and which straddles the shipping area on the ground level. 

"Daily cooperation on-site between SDI and No Limit had to be, and was, extremely good,” says Mariusz Rączka. "We were particularly impressed with SDI’s team of installers and PLC (programmable Logic Controller) programmers to make this installation work as required without the need for any extra supervision or encouragement. SDI also helped us to address the kind of issues that occur during an installation of this type. For example, during the installation SDI moved one of the reject chutes to the other side of the sorter as it was found that this would make it easier for the operators.” 

Streamlined storage
The installation also enabled No Limit to streamline its storage, which is now mostly containers with well defined, dedicated storage for break case picking. To speed up the manual picking process and maximise the sorter’s efficiency, only full boxes are picked. These are brought on pallet trucks to the sorter’s induction station. The boxes are open to minimise the time needed for the operator to take the item and place it onto one of the 500 x 500mm light weight aluminium trays circulating on the sortation system’s conveyor.

Operatives can chose between two induction modes. In fully automatic mode, they simply place items in the trays, ensuring that the bar code is facing upwards or to the left to make it visible to the scanners. The operator can see on the induction screen how many pieces are to be inducted, as well as a progress bar showing the number that have been.

In batch mode, the first item is scanned using a bar code scanner attached to the induction screen, which brings up information on batch composition. The operator then simply places items manually into the trays. The screen’s progress bar informs the operator how many items have been inducted and, when finished, tells the operator they can start another batch. The system also provides the capability to scan individual SKUs for items with poor quality bar codes or barcodes placed in awkward to read places.

The system dynamically allocates a chute to the order in realtime. This gives No Limit enormous flexibility to serve different customers with different sortation schedules. It also maximises utilisation of the chutes because whenever there is a small order and a chute is free, it can be allocated immediately to the next order. So even order batches in excess of the 140 chutes, say 200 orders, can be processed without the need to break the wave into smaller batches.

The trays circulate on the conveyor until they reach the required drop chute allocated to a store order. The PTU unit gently pushes the item into the chute. A standard PTU sorter has 70 chute drops but SDI provided ‘double chutes’ on No Limit’s system, giving 140 upper and lower chute drops, which allows more customers to be handled on the same machine. These chutes are lined up along one side of the circulating conveyor, allowing room for 140 more drops to be installed on the over side during phase 2 of the operation in the summer. 

The chutes drop from the PTU sorter to a platform 4 metres above the shipping area in a non-accumulation mode, so rather than dropping items directly into boxes at the end of the chutes, the system allows operatives to carefully place items into a box to optimise the space. They can work with an assigned section of the chutes and move freely between different chutes to place items into a box. 

These operators use RF (Radio Frequency) terminals loaded with the same software that manages the sortation system’s operation but with additional functionality should an item need to be removed from a box. All updates are carried out in realtime. Any item too big to fit in the 500 x 500 mm tray is treated as an oversize item. Using their RF terminals operatives sort these items manually, directly to the boxes at the end of the chutes.

A display featuring numerical and light indicators at the end of the chutes provides clear information on the number of items sorted to a given chute and the status, for example: there is no box / order assigned to a chute or an order is finished and a new carton can be assigned for a new order. 

In the event of a mechanical error or if a chute is suspended and the item cannot be discharged from a tray, then the item will travel in the tray round the sorter for a specified number of times. If within that time it cannot drop into the correct chute it will be sent to a reject chute. There is also a chute allocated for items where the bar code can’t be recognised. The software registers any errors and the customer can see exactly what has landed where, along with the number of items in a given chute.

Once packed, completed order boxes are placed on a small nearby conveyor and manually pushed to the shipping area. For now, both the closing of the box and the production of the shipping label also remains manual but the plan is to automate these functions in the future.

"Our staff have adapted extremely well to the new system”, says Małgorzata Perkowska, operations manager at No Limit. "Induction operators find it easy to use the touch screen, which simply requires them to choose between two modes. They are presented only with the clear and transparent information that they require. SDI was also able to ensure this was given in Polish. Supervisors can quickly follow up what is happening on management screens and they have been keen to dive into using the system and quick to gain a full grasp of its operation. By training our own staff, we have built a core team that understands the process and can train others how to maintain the extremely high productivity and accuracy SDI Group’s sortation system provides.”

A further big advantage provided by the system is a reduced need to recruit temporary staff during peaks and increased flexibility to rotate staff around induction and packing at end of chutes. No Limit has also found that now that it is fully operational: the sorter is very quiet, contributing to a pleasant working environment.

With Phase 1 now fully operational, and sorting 5000 items per hour, No limit will be going ahead with Phase 2 at the end of the summer, when SDI will install 140 chutes on the other side of the sorter, raising performance to 10,000 items per hour. 

With the software and much of the mechanical installation already in place Phase 2 will be a less extensive operation. The company will then be well placed to add, when ready, a set of feeding conveyors from the storage and the picking areas, as well as an outgoing conveyor from the sorter to despatch.

Marcin Blauth, president of the board concludes: "By providing class leading technology SDI Group has provided No Limit with a complete solution, which can be divided into phases. This enables us to increase growth and volume, while phasing our investment. SDI has also impressed us with their installation and teamwork, which resulted in a close partnership working towards the common goal of increased sortation speed, accuracy and flexibility, which now gives No Limit a powerful selling tool to help us win new business from new customers. Today, when we are close to having sorted one million items, we can safely say that the years of preparation spent on this project, as well as the decision to purchase the sorter from SDI Group were the best decisions we have made.”